BKH


Line plots across dimensions of each concept
Line plots across concepts
Tables

Table of contents



us-gaap:CommonStockValue

us-gaap:CommonStockParOrStatedValuePerShare

us-gaap:CommonStockSharesAuthorized

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:CostOfGoodsAndServicesSold
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:CostsAndExpenses

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:IncomeTaxExpenseBenefit
us-gaap:CumulativeEffectPeriodOfAdoption
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:IncomeTaxesPaidNet

us-gaap:InterestIncomeExpenseNet

us-gaap:InterestPaidNet

us-gaap:NetIncomeLoss
us-gaap:CumulativeEffectPeriodOfAdoption

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NonoperatingIncomeExpense

us-gaap:OperatingExpenses

us-gaap:OperatingIncomeLoss
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherNonoperatingIncomeExpense
us-gaap:CumulativeEffectPeriodOfAdoption

us-gaap:ProfitLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:MajorCustomers
us-gaap:ConsolidationItems, us-gaap:TimingOfTransferOfGoodOrService
us-gaap:MajorCustomers
us-gaap:MajorCustomers, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments, us-gaap:TimingOfTransferOfGoodOrService
us-gaap:TimingOfTransferOfGoodOrService

us-gaap:Revenues
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:ProductOrService
us-gaap:MajorCustomers, us-gaap:ProductOrService
us-gaap:MajorCustomers, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:ProductOrService
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments

us-gaap:Assets
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity

us-gaap:AssetsCurrent
us-gaap:ConsolidatedEntities

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:AccountsReceivableNetCurrent
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:InventoryNet

us-gaap:InventoryRawMaterialsAndSupplies

us-gaap:OtherAssetsCurrent

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems
us-gaap:ConstructionInProgressGross
us-gaap:StatementBusinessSegments

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:PropertyPlantAndEquipmentNet
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:StatementBusinessSegments

us-gaap:LongTermInvestments
us-gaap:FairValueByAssetClass

us-gaap:Goodwill
us-gaap:StatementBusinessSegments

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:OperatingLeaseRightOfUseAsset
us-gaap:BalanceSheetLocation

us-gaap:OtherAssetsNoncurrent

us-gaap:AccountsPayableCurrent

us-gaap:AccruedLiabilitiesCurrent

us-gaap:LiabilitiesCurrent
us-gaap:ConsolidatedEntities

us-gaap:LongTermDebtCurrent
us-gaap:BalanceSheetLocation
us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherAccruedLiabilitiesCurrent
us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebt

us-gaap:LongTermDebtNoncurrent

us-gaap:DeferredFinanceCostsNoncurrentNet

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
us-gaap:RetirementPlanType

us-gaap:OtherLiabilitiesNoncurrent
us-gaap:BalanceSheetLocation
us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:CumulativeEffectPeriodOfAdoption
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapital

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:DerivativeInstrumentRisk, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValue

us-gaap:StockIssuedDuringPeriodValueNewIssues
us-gaap:StatementEquityComponents

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DepreciationDepletionAndAmortization

us-gaap:IncreaseDecreaseInInventories

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss
us-gaap:CumulativeEffectPeriodOfAdoption

us-gaap:ProfitLoss
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:ShareBasedCompensation

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:PaymentsOfDividends

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:ProceedsFromRepaymentsOfShortTermDebt
us-gaap:UnusualOrInfrequentItem
bkh:AmountRecoveredThroughRegulatoryMechanism
dei:LegalEntity, us-gaap:RegulatoryAgency
bkh:AnnualTCJARelatedCustomerBillingCredits
us-gaap:StatementEquityComponents
bkh:AtTheMarketEquityProgramProceedsfromSaleofStock
us-gaap:StatementEquityComponents
bkh:AtTheMarketEquityProgramStockIssuedIssuanceCosts
dei:LegalEntity
bkh:EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit

bkh:EffectiveIncomeTaxReconciliationTaxBenefitFromAmortizationOfExcessDeferredIncomeTaxes

bkh:EffectiveIncomeTaxReconciliationTaxFlowThroughBenefitFromRepairsAndIndirectCosts

bkh:FuelPurchasedPowerAndCostOfGasSold
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:IncomeStatementLocation, us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem
bkh:IncomeStatementImpacts
us-gaap:IncomeStatementLocation, us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem
us-gaap:IncomeStatementLocation, us-gaap:UnusualOrInfrequentItem
us-gaap:UnusualOrInfrequentItem

bkh:IncomeTaxBenefitFromRelievedTCJARelatedLiabilities
us-gaap:UnusualOrInfrequentItem
bkh:IncrementalFuelPurchasedPowerAndNaturalGasCosts

bkh:NetPaymentsBorrowingsOfRevolvingCreditFacilityAndCommercialPaperProgram

bkh:OperatingExpenseMaintenanceOperationsandOtherCostsandExpense
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested
us-gaap:SubsequentEventType
bkh:SubsequentEventEstimatedCostOfIncrementalGasPurchasesDueToHistoricColdWeatherEvent

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts
us-gaap:StatementEquityComponents

us-gaap:AllowanceForDoubtfulAccountsReceivableRecoveries

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs

us-gaap:AmortizationOfFinancingCostsAndDiscounts

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths

us-gaap:CommonStockDividendsPerShareCashPaid
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanContributionsByEmployer
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanInterestCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost
us-gaap:Energy, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation
us-gaap:DerivativeGainLossOnDerivativeNet
us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation
us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:DividendsCommonStockCash
us-gaap:StatementEquityComponents
us-gaap:PublicUtility
us-gaap:IncomeTaxReconciliationDeductionsQualifiedProductionActivities

us-gaap:IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets

us-gaap:IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInOtherRegulatoryAssets

us-gaap:IncreaseDecreaseInRegulatoryLiabilities

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InterestCostsIncurred
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:InvestmentIncomeInterest

us-gaap:OtherAssetImpairmentCharges

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax
us-gaap:DerivativeInstrumentRisk, us-gaap:StatementEquityComponents
us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect
us-gaap:DerivativeInstrumentRisk
us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax
us-gaap:DerivativeInstrumentRisk
us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax
us-gaap:DerivativeInstrumentRisk
us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax
us-gaap:DerivativeInstrumentRisk
us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax

us-gaap:OtherCostAndExpenseOperating
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:OtherNoncashIncomeExpense

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsToMinorityShareholders

us-gaap:PensionAndOtherPostretirementBenefitExpense

us-gaap:PensionContributions

us-gaap:ProceedsFromIncomeTaxRefunds

us-gaap:ProceedsFromIssuanceOfCommonStock
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:DebtInstrument, us-gaap:SubsequentEventType
us-gaap:ProceedsFromIssuanceOfDebt

us-gaap:ProceedsFromOtherShortTermDebt

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProvisionForDoubtfulAccounts
us-gaap:AccountsNotesLoansAndFinancingReceivableByReceivableType
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesRequestedRateIncreaseDecreaseAmount
us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents
us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:RepaymentsOfOtherShortTermDebt
us-gaap:DebtInstrument, us-gaap:ShortTermDebtType

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation
us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityOther
us-gaap:StatementEquityComponents
dei:LegalEntity, us-gaap:RegulatoryAgency
us-gaap:TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit

us-gaap:TaxesExcludingIncomeAndExciseTaxes

bkh:AmountOfPayrollTaxSocialSecurityEmploymentTaxDeferralAllowedUnderTheCARESAct

bkh:AtTheMarketEquityOfferingProgramAuthorizedAggregateValue
us-gaap:SubsequentEventType

bkh:CustomerDepositsandPrepayments

bkh:DeferredTaxLiabilityState
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType
bkh:DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets
us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
bkh:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicBenefitCostExpectedRateofReturnOnAssetsForNextFiscalYear
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType
bkh:DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments
us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType
us-gaap:AwardType
bkh:EmployeeServiceShareBasedCompensationOtherThanOptionsTotalPayoutValue

bkh:LeaseLiability

bkh:LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts
dei:LegalEntity, us-gaap:ConsolidationItems
dei:LegalEntity, us-gaap:StatementBusinessSegments
bkh:FuelType, dei:LegalEntity, us-gaap:LongTermContractForPurchaseOfElectricPower
bkh:NumberOfMegawattsCapacityPurchased
bkh:FuelType, us-gaap:LongTermContractForPurchaseOfElectricPower
dei:LegalEntity, us-gaap:LongTermContractForPurchaseOfElectricPower
dei:LegalEntity, us-gaap:RegulatoryAgency
dei:LegalEntity, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType
us-gaap:LongTermContractForPurchaseOfElectricPower
dei:LegalEntity, us-gaap:RegulatoryAgency
bkh:NumberofMegawattsSoldUnderLongTermContract
us-gaap:RelatedPartyTransaction
us-gaap:IncomeTaxAuthority
bkh:OperatingLossCarryforwardsWithNoExpirationDate
us-gaap:Range, us-gaap:DefinedBenefitPlanByPlanAssetCategories
bkh:PercentageOfMonthlyRedemption
us-gaap:ConsolidationItems
bkh:PropertyPlantEquipmentExcludingConstructionInProgress
us-gaap:StatementBusinessSegments
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
bkh:PublicUtilitiesDevelopmentCostsExpensed
us-gaap:StatementBusinessSegments
bkh:PublicUtilitiesPropertyPlantandEquipmentExcludingConstructioninProgress
dei:LegalEntity, us-gaap:RegulatoryAgency
bkh:SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers
dei:LegalEntity, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType
us-gaap:AwardType
bkh:SharebasedCompensationArrangementbySharebasedPaymentAwardPayoutPercentageofTarget
bkh:NaturalGasIndices
bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFiveYears
bkh:NaturalGasIndices
bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFourYears
bkh:NaturalGasIndices
bkh:UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears
bkh:NaturalGasIndices
bkh:UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears
bkh:NaturalGasIndices
bkh:UnrecordedUnconditionalPurchaseObligationDueintheNextTwelveMonths

us-gaap:AccountsReceivableGrossCurrent
us-gaap:AccountsNotesLoansAndFinancingReceivablesByBillingStatusType
us-gaap:AccountsNotesLoansAndFinancingReceivablesByBillingStatusType, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:AccountsNotesLoansAndFinancingReceivablesByBillingStatusType
us-gaap:StatementBusinessSegments
us-gaap:AccrualForEnvironmentalLossContingencies
dei:LegalEntity, us-gaap:EnvironmentalRemediationSite, us-gaap:StatementBusinessSegments
us-gaap:AccrualForEnvironmentalLossContingenciesGross

us-gaap:AccrualForTaxesOtherThanIncomeTaxesCurrent
us-gaap:RetirementPlanType
us-gaap:AccumulatedOtherComprehensiveIncomeLossDefinedBenefitPensionAndOtherPostretirementPlansNetOfTax

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent
us-gaap:AccountsNotesLoansAndFinancingReceivableByReceivableType
us-gaap:StatementBusinessSegments
bkh:BusinessGroup
us-gaap:AmountOfRestrictedNetAssetsForConsolidatedAndUnconsolidatedSubsidiaries

us-gaap:AssetRetirementObligation
us-gaap:StatementBusinessSegments
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:AssetsNoncurrentOtherThanNoncurrentInvestmentsAndPropertyPlantAndEquipment

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations

us-gaap:CollateralAlreadyPostedAggregateFairValue
us-gaap:DerivativeInstrumentRisk

us-gaap:CommonStockCapitalSharesReservedForFutureIssuance
dei:LegalEntity, us-gaap:ConsolidationItems
us-gaap:DebtInstrumentCarryingAmount
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:DebtInstrument
dei:LegalEntity, us-gaap:StatementBusinessSegments
us-gaap:DebtInstrument
us-gaap:DebtInstrumentFaceAmount
us-gaap:DebtInstrument, us-gaap:ShortTermDebtType
dei:LegalEntity, us-gaap:ConsolidationItems
us-gaap:DebtInstrumentUnamortizedDiscount
dei:LegalEntity, us-gaap:StatementBusinessSegments
us-gaap:ShortTermDebtType
us-gaap:DebtWeightedAverageInterestRate

us-gaap:DeferredFinanceCostsNet
us-gaap:CreditFacility
us-gaap:CreditFacility
us-gaap:DeferredFinanceCostsNoncurrentGross

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredTaxAssetsInvestments

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards

us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal
us-gaap:IncomeTaxAuthority, us-gaap:ValuationAllowanceByDeferredTaxAsset

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsRegulatoryAssetsAndLiabilities
us-gaap:IncomeTaxAuthority, us-gaap:TaxCreditCarryforward
us-gaap:DeferredTaxAssetsStateTaxes

us-gaap:DeferredTaxAssetsTaxCreditCarryforwards

us-gaap:DeferredTaxAssetsTaxCreditCarryforwardsOther

us-gaap:DeferredTaxLiabilitiesGoodwillAndIntangibleAssetsGoodwill

us-gaap:DeferredTaxLiabilitiesOther

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment

us-gaap:DeferredTaxLiabilitiesRegulatoryAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesAfterTax
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditAfterTax
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsNextFiscalYear
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureEmployerContributionsRemainderOfFiscalYear
dei:LegalEntity, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
us-gaap:DefinedBenefitPlanByPlanAssetCategories
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeAssetFairValueGrossLiabilityAndObligationToReturnCashOffset
us-gaap:FairValueByMeasurementFrequency, us-gaap:StatementBusinessSegments

us-gaap:DerivativeAssetsCurrent
bkh:NettingContractCategory
us-gaap:DerivativeFairValueOfDerivativeAsset
bkh:NettingContractCategory
us-gaap:DerivativeFairValueOfDerivativeLiability

us-gaap:DerivativeLiabilitiesCurrent
us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeLiabilityFairValueGrossAssetAndRightToReclaimCashOffset
us-gaap:FairValueByMeasurementFrequency, us-gaap:StatementBusinessSegments
us-gaap:Energy, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeNonmonetaryNotionalAmount
us-gaap:Energy, us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:TransactionType
us-gaap:Energy, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
us-gaap:AwardType
us-gaap:AwardType
us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedShareBasedAwardsOtherThanOptions

us-gaap:EnergyRelatedInventoryNaturalGasInStorage

us-gaap:EnergyRelatedInventoryOtherFossilFuel
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:FairValueHedgeAssetsAtFairValue
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:FairValueHedgeLiabilitiesAtFairValue
us-gaap:DerivativeInstrumentRisk, us-gaap:HedgingDesignation
us-gaap:FairValueHedgesAtFairValueNet

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFive

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearFour

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearThree

us-gaap:FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo
us-gaap:GuaranteeObligationsByNature
us-gaap:GuaranteeObligationsMaximumExposure

us-gaap:IncomeTaxesReceivable
us-gaap:EnvironmentalRemediationSite, us-gaap:StatementBusinessSegments
us-gaap:InsuranceSettlementsReceivableNoncurrent

us-gaap:InterestPayableCurrent
us-gaap:JointlyOwnedUtilityPlant, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService
us-gaap:JointlyOwnedUtilityPlant, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlantNetOwnershipAmount
us-gaap:JointlyOwnedUtilityPlant, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
us-gaap:JointlyOwnedUtilityPlant, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LessorOperatingLeasePaymentsToBeReceived

us-gaap:LessorOperatingLeasePaymentsToBeReceivedFiveYears

us-gaap:LessorOperatingLeasePaymentsToBeReceivedFourYears

us-gaap:LessorOperatingLeasePaymentsToBeReceivedNextTwelveMonths

us-gaap:LessorOperatingLeasePaymentsToBeReceivedThereafter

us-gaap:LessorOperatingLeasePaymentsToBeReceivedThreeYears

us-gaap:LessorOperatingLeasePaymentsToBeReceivedTwoYears

us-gaap:LettersOfCreditOutstandingAmount
us-gaap:CreditFacility
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:LiabilitiesFairValueDisclosure
us-gaap:FairValueByMeasurementBasis, us-gaap:FairValueByMeasurementFrequency

us-gaap:LiabilitiesOtherThanLongtermDebtNoncurrent

us-gaap:LiabilityForUncertainTaxPositionsNoncurrent
us-gaap:CreditFacility
us-gaap:LineOfCreditFacilityCurrentBorrowingCapacity
us-gaap:CreditFacility, us-gaap:VariableRate
us-gaap:LineOfCreditFacilityInterestRateAtPeriodEnd
us-gaap:CreditFacility, us-gaap:SubsequentEventType
us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity
us-gaap:SubsequentEventType
us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebtFairValue

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:StatementBusinessSegments
us-gaap:LongTermDebtPercentageBearingVariableInterestRate

us-gaap:NoncontrollingInterestInVariableInterestEntity

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent
us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwards
us-gaap:IncomeTaxAuthority, us-gaap:ValuationAllowanceByDeferredTaxAsset
us-gaap:OperatingLossCarryforwardsValuationAllowance
us-gaap:RetirementPlanType
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress
us-gaap:PropertyPlantAndEquipmentByType, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentDistribution
us-gaap:PropertyPlantAndEquipmentByType, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentGenerationOrProcessing
us-gaap:PropertyPlantAndEquipmentByType, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyPlantAndEquipment
us-gaap:PropertyPlantAndEquipmentByType, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentTransmission

us-gaap:RatioOfIndebtednessToNetCapital1

us-gaap:RegulatoryAssets
dei:LegalEntity, us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem
us-gaap:EnvironmentalRemediationSite, us-gaap:RegulatoryAsset, us-gaap:StatementBusinessSegments
us-gaap:RegulatoryAsset
us-gaap:RegulatoryAsset, us-gaap:UnusualOrInfrequentItem
us-gaap:RetirementPlanType
us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem
us-gaap:UnusualOrInfrequentItem

us-gaap:RegulatoryAssetsCurrent

us-gaap:RegulatoryAssetsNoncurrent

us-gaap:RegulatoryLiabilities
us-gaap:RegulatoryLiability
us-gaap:RetirementPlanType

us-gaap:RegulatoryLiabilityCurrent

us-gaap:RegulatoryLiabilityNoncurrent

us-gaap:RestrictedCashAndInvestmentsCurrent
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber

us-gaap:ShortTermBorrowings
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:DebtInstrument, us-gaap:SubsequentEventType
us-gaap:ShortTermDebtType
us-gaap:DebtInstrument, us-gaap:ShortTermDebtType
us-gaap:ShortTermDebtPercentageBearingVariableInterestRate
us-gaap:ShortTermDebtType
us-gaap:ShortTermDebtWeightedAverageInterestRate
us-gaap:IncomeTaxAuthority
us-gaap:TaxCreditCarryforwardValuationAllowance

us-gaap:UnbilledReceivablesCurrent

us-gaap:UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceOnFifthAnniversary
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceOnFirstAnniversary
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceOnFourthAnniversary
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceOnSecondAnniversary
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationBalanceOnThirdAnniversary
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased
us-gaap:UnrecordedUnconditionalPurchaseObligationDueAfterFiveYears

Plots across concepts


IncomeStatement
Other Comprehensive Income Loss Net Of Tax
Expenses
Other Nonoperating Income Expense
Balance Sheet
Cash And Cash Equivalents At Carrying Value
Assets
Cash And Cash Equivalents At Carrying Value
Current Assets
Cash And Cash Equivalents At Carrying Value
NonCurrent Assets
Operating Lease Right Of Use Asset
PropertyPlantAndEquipmentNet
Accumulated Depreciation Depletion And Amortization Property Plant And Equipment
Liabilities
Liabilities Current
Current Liabilities
Long Term Debt Current
Noncurrent Liabilities
Other Liabilities Noncurrent
Stockholders Equity
Accumulated Other Comprehensive Income Loss Net Of Tax
Per Share
Earnings Per Share Diluted
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Share Based Compensation
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Proceeds From Issuance Of Long Term Debt
Shares
Weighted Average Number Of Shares Outstanding Basic
NonoperatingIncomeExpense
Nonoperating Income Expense
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Payments Due Year Four
AccountsReceivable
Allowance For Doubtful Accounts Receivable Current

Tables

  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:CommonStockValue ██████▇▇▇▇▇▅▅▅▅▅▅▅▅▅▅▅▄▃▃▃▃▃▃▃▃▃▃▃▂▂▂▂▂▁▁▁▁▁▁▁63.52762.9162.82762.77362.77362.77361.48161.48161.09160.37860.04953.66253.66253.64953.5853.52553.51453.50253.39753.13152.29951.47751.23244.89244.87244.85744.71444.69744.68344.66744.5544.53244.51744.48244.27844.25144.17744.15143.95839.49239.46239.43439.2839.24339.20439.178
us-gaap:CommonStockParOrStatedValuePerShare NANA1e-06NA1e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-061e-060.0011e-061e-061e-061e-061e-061e-061e-061e-06
us-gaap:CommonStockSharesAuthorized ▄▄▄100.0100.0100.0NA100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100000.0100000.0100.0100.0100.0100.0100.0100.0100.0
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding █▁62.91862.691NA62.6362.61761.856NA61.10460.60660.06NA54.81954.5254.122NA55.43255.38454.932NA53.73352.98651.858NA44.63544.61744.66NA44.60844.58844.554NA44.45744.41244.312NA44.10843.79943.969NA39.14539.82339.761NA39.13338.90239.009
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁62.86762.633NA62.57562.57361.778NA60.97660.46759.92NA53.36453.35553.319NA53.24353.22953.152NA52.18451.51451.044NA44.63544.61744.541NA44.41544.39944.33NA44.20144.17244.053NA43.84743.79943.731NA39.14539.10939.059NA38.93338.90238.848
us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount ▁█0.0130.033NA0.0710.1050.038NA0.0020.00.006NA0.0120.0150.071NA0.00.00.0NA0.0020.0040.074NA0.1210.1190.107NA0.0990.0810.046NA0.00.0280.04NA0.1380.2070.174NA0.2230.1570.09NA0.1310.309NA
us-gaap:EarningsPerShareBasic ▄▆▅▄▄▆▅▃▃▆▆▄▄█▅▄▄▆▄▃▃▅▂▂▁▅▄▄▄▅▄▄▄▅▄▅▂▄▄▂▃▄▅▄▂▅0.41.541.23999999999999980.580.341.511.130.190.241.731.50.320.412.490.950.520.421.440.340.270.010.78-0.3-0.22-0.941.080.770.60.451.090.410.520.690.980.70.79-0.310.680.61-0.270.20.690.860.32-0.220.81
us-gaap:EarningsPerShareDiluted ▄▆▅▄▄▆▅▃▃▆▆▄▄█▅▄▄▆▄▃▃▅▂▂▁▅▄▄▄▅▄▄▄▅▄▅▂▄▄▂▃▄▅▄▂▅0.41.541.23999999999999980.580.331.511.130.190.241.731.490.310.42.460.920.50.41.390.330.260.010.77-0.3-0.22-0.941.070.760.60.441.080.410.520.690.970.70.78-0.310.680.6-0.270.190.680.850.32-0.220.81
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 Operating Margin us-gaap:StatementBusinessSegments bkh:ElectricUtilities▁█184.933227.408NA200.842163.2174.139NA191.384166.354182.927179.49184.79173.616173.555NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin us-gaap:StatementBusinessSegments bkh:GasUtilities▁█186.05402.519NA143.929161.11360.773NA130.744165.469411.08318.667131.676177.62397.344NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin us-gaap:StatementBusinessSegments bkh:Mining▁█14.42914.672NA15.23615.41615.205NA15.55213.04516.42916.70517.30116.89917.128NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin us-gaap:StatementBusinessSegments bkh:PowerGeneration▁█25.34829.163NA26.51826.12225.966NA25.81124.70825.24520.36223.60322.74423.939NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 TTM Greenblatt ROC _ _▅▇▇▅▅█▇▅▄█▆▅▅█▆▅▅█▄▄▄▅▂▂▁▆▅▄▄▆▅▄▄▅▅▅▃▅▄▄▄▄▄67.266138.315125.95182.23466.933153.185121.35970.55154.001160.131114.12765.08569.551148.274117.19578.51968.866147.51155.28958.40935.29873.590.197-2.044-38.85891.95269.95154.40446.57789.59871.10355.56649.03779.84675.26277.8120.59170.04852.1441.43942.62255.71346.857NANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:ComprehensiveIncomeNetOfTax ▄▇▆▄▄▆▅▃▃▇▆▃▄█▅▄▄▆▃▃▂▄▂▂▁▄27.04397.33476.76137.79521.91494.44764.21912.27214.815104.26590.11718.0123.078134.26449.01728.03822.98477.67616.23612.944-10.2728.232-8.62-7.695-44.64734.84NANANANANANANANANANANANA-34.35-8.3188.04NA-36.33710.424-13.243NA
us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▄▇▆▄▄▆▅▃▃▇▆▄▄█▅▄▄▆▃▃▂▄▂▂▁▅▄▄▃▅▄▄▄▄▆▃▃▃▂▃▃▃30.169101.50580.07241.86125.64298.49767.91215.92717.925107.81993.8922.00425.901137.89452.58531.97326.181.29919.48216.697-7.65628.28-8.62-7.695-44.64748.88433.80231.43818.96846.95131.72222.88435.96142.46183.255-3.563-0.608-0.166-10.2132.2070.288-1.579NANANANA
us-gaap:CostOfGoodsAndServicesSold NANANA71.686NANANA73.544NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CostOfGoodsAndServicesSold us-gaap:DerivativeInstrumentRisk,us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:StatementEquityComponents us-gaap:CommodityContract,us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome,us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesNANANA-0.178NANANA-0.129NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:CostsAndExpenses NANA-356.425264.356NANA-423.654254.997NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA29.211NANANA22.96
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments ▄▇▇▅▄█▆▄▄█▆▄▄█▇▅▅█▄▄▃▅▂▂▁▆▅▅▄▆▄▅▅▆▅▅▂▅▄▂▄▅▅▄▃▅28.873100.98187.9345.029.525113.22680.37417.90320.0124.62579.72129.27833.708113.17587.12545.40335.713113.50120.68424.5283.59244.302-22.461-21.978-56.94273.31152.05338.16830.47173.48530.08836.45846.13464.8649.25552.515-19.91955.04424.613-18.72712.75638.82648.85811.066-15.09347.593
us-gaap:IncomeTaxExpenseBenefit ▄▄▅▅▅▆▅▄▄▆▃▅▅▁▆▆▅█▄▅▄▅▃▃▂▇▆▅▅▇▅▆▆▇▆▆▃▆▅▃▅▆▆▄▃▆0.5860.4947.4344.6514.83116.0027.5022.5082.30717.263-11.8837.4776.541-25.80215.80513.80510.40233.355-0.736.6440.3094.252-7.52-12.035-20.31725.1218.04611.33210.65125.36611.08113.33415.61621.57718.34317.914-7.57419.7178.43-8.1595.04412.90915.426-1.461-5.14316.476
us-gaap:IncomeTaxesPaidNet ▄▄▄▄▃▄▃▄▃▄▄▄▄█▃▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▅▅▄▄▄▅▄▁▄▁▄-0.496-0.99-0.9160.64-1.8960.0-2.427-0.465-1.782-0.008-0.1120.0050.50114.336-1.7740.00.012-0.013-0.0120.0061.1620.00.00.01.20.0020.0170.00.4-0.004-0.351-0.4820.754.6563.452-0.808-1.4551.8381.972-1.188-10.59-0.048-9.8720.089NANA
us-gaap:InterestIncomeExpenseNet ▁█-38.202-37.6NA-36.041-35.545-35.453NA-33.487-34.265-34.717NA-35.297-34.534-34.995NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InterestPaidNet █▃█▃▇▃▅▅▆▄▅▆▄▆▄▅▄▅▄▅▅▂▄▁▄▁▃▁▃▁█▁▅▁▇▂▆▂▆▁▆▁▆▅50.59321.23249.09620.00445.67321.77632.39931.75136.95230.67233.9336.91630.19136.92830.58836.0229.45836.36230.28634.532.61115.52828.01312.09926.78910.90923.15311.07723.55711.45251.18612.98431.42312.76846.69214.53738.56516.79941.64911.55238.33711.57239.20735.859NANA
us-gaap:NetIncomeLoss ▂▆▅▂▂▆▄▁▁▆▅▁▂█25.16196.31677.18536.28320.96693.17469.17911.7414.583103.80886.57116.9521.917133.004NANANANANANANANANANANANANANANANANANANANA30.76734.457-13.48329.78725.593-10.5257.75226.9133.5212.39-8.65931.434
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▆█▇█▇█▇▇▆▇▇█▆▇▇█▆▇▆▇▅▁▁▁▁3.1264.1713.3114.0663.7284.053.6933.6553.113.5543.7733.9942.8233.633.5683.9353.1163.6233.2463.7532.6140.0480.00.00.0NANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic NANANA36.28320.96693.174NA11.7414.583103.80886.57116.9521.917133.00450.65327.66322.19576.52318.16814.1310.66940.002-14.176-9.943-41.84247.89434.00726.83619.8248.11818.12323.12430.51843.19730.76734.457-13.48329.787NANANANANANANANA
us-gaap:NonoperatingIncomeExpense ▂▂▂▂▂▂█▁▂▂█▂▂▂▇▂▂▂▇▂-38.393-37.334-38.021-37.234-37.408-39.959116.415-52.648-34.001-35.506105.569-35.807-35.843-35.099102.387-33.116-33.217-34.08399.269-33.881NANANANANANANANANANANANANANANANANANANANANA-16.887NANANA-22.109
us-gaap:OperatingExpenses ▁█305.306495.117NANA259.981383.865356.295254.997279.887437.679387.069256.894286.153427.115314.307263.619279.112406.492408.499275.377290.143376.369318.062274.149311.112350.035308.126217.683236.66370.571284.345204.341230.789300.825243.6168.998221.772295.803292.838215.021230.503347.587329.496201.552225.503356.798
us-gaap:OperatingIncomeLoss ▅▇▇▅▅█▇▅▄█▆▅▅█▆▅▅█▄▄▄▅▂▂▁▆▅▄▄▆▅▄▄▅▅▅▃▅▄▄▄▄▄▄▃▅67.266138.315125.95182.23466.933153.185121.35970.55154.001160.131114.12765.08569.551148.274117.19578.51968.866147.51155.28958.40935.29873.590.197-2.044-38.85891.95269.95154.40446.57789.59871.10355.56649.03779.84675.26277.8120.59170.04852.1441.43942.62255.71346.85747.94230.83569.702
us-gaap:OtherComprehensiveIncomeLossNetOfTax ▅▅▅▅▅▅▅▅▅▅▆▅▅▅▅▅▅▅▅▅▄▄▆▅▅▅▅▆▅▅▆▅▆▅▁█▅▅▂▅1.8821.018-0.4241.5120.9481.273-4.960.5320.2320.4573.5461.061.1611.26-1.6360.3750.7891.153-1.932-1.187-10.939-11.775.5562.248-2.8050.99-0.2054.602-0.852-1.16713.599-0.245.443-0.736-49.03430.894-0.608-0.166-34.35-8.318NANANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▅▅▄▄▄▆▁▅▅▄▅▄▄▅▆▅▅▅▇▅▅▅▅▅▅▅▆▅▅▅▅▅▅▅▅▅▅▆▆▅▅▅█▅▆▅-0.1910.266-1.59-1.193-1.8632.353-5.7810.2690.137-0.8370.627-0.703-1.551-0.1722.0790.189-0.058-0.1023.7020.16-0.0470.6880.8690.8420.3950.3311.4190.2610.4090.5920.6010.3180.4740.4050.892-0.2870.8881.4721.9650.5240.5060.7314.9230.5391.2680.418
 us-gaap:OtherNonoperatingIncomeExpense us-gaap:CumulativeEffectPeriodOfAdoption srt:CumulativeEffectPeriodOfAdoptionAdjustmentNANA0.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▄▇▆▄▄▆▅▃▃▇▆▃▄█▅▄▄▆▃▃▃▄▂▂▁▄28.287100.48780.49640.34924.69497.22472.87215.39517.693107.36290.34420.94424.74136.63454.22131.59825.31180.14621.41417.8843.28340.05-14.176-9.943-41.84233.85NANANANANANA30.51843.19730.76734.457-13.48329.78725.593-10.5257.75226.91NANANA31.434
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▃█▅▃▂▆▅▂▃▇▆▂▃▇▅▃▃▇▅▃▂▅▂▂▂▅▃▂▂▅▃▁▂▃▂▁▁▃▃▁▂▄▂▁▁▄368.423630.217482.09344.312324.193530.209477.654323.745329.746597.97501.196320.163352.461573.355455.298335.611341.829547.528463.788333.786325.441449.959318.259272.105272.254441.987378.077272.087283.237460.169355.448259.907279.826380.671318.862246.808242.363365.851361.181256.46273.125400.835314.999249.494256.338416.728
us-gaap:Revenues ▃█▅▃▃▆▅▂▃▇▆▂▃▇▅▃▃▆▅▃▂▅▂▂▂▅▃▂▂▅▃▁▂▃▂▁▁▃▃▁▂▄▂▁▁▄372.572633.432486.387346.59326.914537.05477.654325.548333.888597.81501.196321.979355.704575.389455.298335.611341.829547.528463.788333.786325.441449.959318.259272.105272.254441.987378.077272.087283.237460.169355.448259.907279.826380.671318.862246.808242.363365.851361.181256.46273.125400.835314.999249.494256.338416.728
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:Assets ██▇▇▇▇▆▆▆▆▆▅▅▅▅▅▅▅▅▅▅▅▃▂▂▂▂▂▂▂▂▂▂▁▁▂▂▂▂▂▂▁▁▁▁▁8738.0528696.1998088.7867829.057689.9327648.8147558.4577274.957081.4537037.5726963.3276661.9386570.1296626.9896658.9026551.1776489.0926475.8496515.4446452.1366394.8646324.6534655.5014246.5624220.2714319.8284279.8064073.2623970.4983964.9643875.1783801.243746.5143686.5863729.4713853.6283774.283807.9364127.0833953.3673810.7643727.0283711.5093540.2373370.2823358.639
us-gaap:LiabilitiesAndStockholdersEquity ██▇▇▇▇▆▆▆▆▆▅▅▅▅▅▅▅▅▅▅▅▃▂▂▂▂▂▂▂▂▂▂▁▁▂▂▂▂▂▂▁▁▁▁▁8738.0528696.1998088.7867829.057689.9327648.8147558.4577274.957081.4537037.5726963.3276661.9386570.1296626.9896658.9026551.1776489.0926475.8496515.4446452.1366394.8646324.6534655.5014246.5624220.2714319.8284279.8064073.2623970.4983964.9643875.1783801.243746.5143686.5863729.4713853.6283774.283807.9364127.0833953.3673810.7643727.0283711.5093540.2373370.2823358.639
us-gaap:StockholdersEquity ███▇▇▇▆▆▆▆▆▄▄▄▃▃▃▃▃▃▂▂▂▁▁2659.042624.5132561.3852519.0462513.2922523.1682362.1232329.4782316.752279.1592181.5881813.2551818.8461818.771708.9741682.8041676.2391674.3161614.6391604.6421562.4271480.6831465.8671287.2121310.886NA1376.024NANANA1307.748NANANA1232.5091214.3171196.2851224.6921209.3361088.0051108.0691113.1471100.271080.4071082.3831107.998
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AssetsCurrent ▄▅▃▂▂▃▃▂▂▃▃▂▂▃▄▂▁▂▃▂▃▂█▂▃▃▃▂▁▂▁▁▁▁▂▄▁▂▇▆▅▅▆▅▄▅571.739578.615493.291403.657414.105489.673473.184377.421369.673484.57503.833384.92380.652492.105570.782385.018359.256401.402466.814418.171443.734423.146822.151402.282438.572438.685454.036373.952344.055404.416345.288328.897338.072343.723405.106570.918336.003407.129758.921666.068616.888611.793670.871644.578553.172625.986
us-gaap:CashAndCashEquivalentsAtCarryingValue ▁▁▁▁▁▂▁▁▁▁▁▁▁▁▁▁▁▁▁▂▃▂█▂▂▂▁▁▁▁▁▁▁▁▁▅▂▂▁▂▂▂▁▂▂▃1.17513.4426.3566.95531.60854.1379.77713.0876.64212.22520.77610.0018.6330.94715.4213.5111.5911.35313.5862.964116.80546.974456.53538.84187.2163.38521.21811.93914.69717.6417.84113.63730.63312.39715.462247.19240.1156.13221.62874.77988.07344.01632.43858.97564.033136.023
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents ▁▃▂▂▅█▂▂▂▂▃▂▂▅▃▂▂▂▂5.73417.92510.73911.21235.71358.16413.65816.77510.24415.71924.14513.24211.71433.90518.2416.13214.06213.715.792NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccountsReceivableNetCurrent ▄▇▆▃▃▅▆▂▃▇▆▃▃▆▅▃▃▅▆▃▂▄▂▁▂▃▄▂▂▄▃▁▂▃▃▁▁▂▃▅▅▇█▅▄▅189.437282.382265.961160.478170.98238.903255.805148.989166.513282.602269.153152.796175.612257.772248.33153.832169.957224.714263.289154.617150.227206.276147.486115.502123.661178.421189.992123.399135.145203.625177.573114.137132.726168.783163.698104.482109.157143.987156.774241.831244.829306.07328.811234.48208.185242.189
us-gaap:InventoryNet ▅▄▆▆▅▄▆▆▄▃▆▆▄▃▅▆▄▃▅▅▃▂▃▃▂▁▃▅▃▁▃▄▂▁▂▃▁▁▃▇▅▂██▇▃114.089102.603117.4126.358105.98792.894117.172123.002102.8387.676117.299122.61895.45482.045113.283126.5299.12684.484107.21113.47585.18978.17686.94390.34973.74966.62691.191105.72681.16466.18788.47895.2373.76864.18977.64380.961.45563.23684.064134.463105.60869.341139.677145.251135.04991.111
us-gaap:InventoryRawMaterialsAndSupplies ▇▇▇██▇▇▇▇▆▆▆▆▆▅▆▆▆▅▅▅▅▄▄▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁85.27788.08885.2593.06992.28488.34682.80981.38280.63976.72875.08173.77773.07572.04569.73273.93872.39771.82368.45667.25767.4466.54255.72653.83854.64652.42949.55552.68251.92550.72750.19650.56451.33450.40143.39743.84741.96344.36140.83837.61136.68534.12931.74931.19232.361NA
us-gaap:OtherAssetsCurrent ▂▂▃▃▃▃▃▃▃▃▃▃▃▂▂▃▂▂▃▃▃▄█▆▆▅▂▃▂▂▃▃▃▃▃▅▃▃▂▇▆▇▂▂▁▃22.35325.72226.22133.28727.98126.19826.47929.10627.20928.02929.98232.69131.43124.97225.36726.79321.8423.42527.06330.03230.65234.28771.76355.38351.31547.44824.84226.50221.6624.56325.87727.07527.59528.2628.79544.82326.59126.54621.26665.88956.81960.80425.57120.93213.33926.189
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:PropertyPlantAndEquipmentGross ███▇▇▇▇▆▆▆▆▅▅▅▅▇▆▆▆▆▆▆▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁7558.2047415.8187305.537128.3876954.2746808.2616784.6796567.2296317.1126127.056000.0155819.05702.0655608.5395567.5186615.0986533.5816436.616412.2236306.1196209.8166063.9434976.7784882.424726.4784652.0584563.44493.6964408.2914318.1944259.4454152.0974066.5023977.7043930.7723950.2223863.383800.0113724.0163664.9673559.6273461.5593359.7623243.6413141.0293045.126
 us-gaap:ConstructionInProgressGross us-gaap:ConsolidationItems us-gaap:CorporateNonSegmentNANA16.402NANANA23.334NANANA16.548NANANA6.374NANANA11.974NANANA15.377NANANA5.196NANANA5.647NANANA3.875NANANANANANANANANANANA
 us-gaap:ConstructionInProgressGross us-gaap:StatementBusinessSegments bkh:MiningNANA0.988NANANA1.275NANANA0.0NANANA0.0NANANA4.642NANANA3.649NANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:ConstructionInProgressGross us-gaap:StatementBusinessSegments bkh:PowerGenerationNANA4.876NANANA2.121NANANA11.796NANANA0.224NANANA1.298NANANA2.182NANANA2.262NANANA10.491NANANA1.323NANANA0.93NANANA163.291NANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment ▄▄▄▄▃▃▄▃▃▃▃▃▃▂▂████▇▇▆▆▆▅▄▄▄▄▄▄▄▃▃▃▃▂▂▂▂▂▁▁▁▁▁1361.4531320.5251285.8161276.411251.0751223.9791281.4931243.7941224.61187.1121145.1361118.7831087.6891048.9331026.0882020.3311981.881943.5381943.2341841.1161819.8861742.071717.6841617.7231522.9691351.8571324.0251338.5091325.661298.3981269.1481258.451234.5781210.8331188.0231253.8081006.827980.944934.441934.112916.22889.031864.329880.938852.414830.423
us-gaap:PropertyPlantAndEquipmentNet ███▇▇▇▇▆▆▆▆▅▅▅▅▅▅▅▅▅▅▅▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁6196.7516095.2936019.7145851.9775703.1995584.2825503.1865323.4355092.5124939.9384854.8794700.2174614.3764559.6064541.434594.7674551.7014493.0724468.9894465.0034389.934321.8733259.0943264.6973203.5093300.2013239.3753155.1873082.6313019.7962990.2972893.6472831.9242766.8712742.7492696.4142856.5532819.0672789.5752730.8552643.4072572.5282495.4332362.7032288.6152214.703
us-gaap:LongTermInvestments NANA15.8115.65915.43815.2521.92921.58341.27141.24741.01341.20241.14840.92713.0912.94712.76112.71212.56112.41612.36312.12611.98512.14812.09817.2117.29417.14417.09616.91616.69716.61216.56616.54516.40216.27316.20816.45117.26117.33817.30217.08817.7817.98118.26118.466
 us-gaap:LongTermInvestments us-gaap:FairValueByAssetClass us-gaap:CashSurrenderValueNANA13.62813.46713.42313.23513.05612.907NANA12.81213.06813.01412.82713.0912.94712.76112.712NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermInvestments us-gaap:FairValueByAssetClass us-gaap:EquitySecuritiesNANA1.51.51.51.58.359NANANA28.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LongTermInvestments us-gaap:FairValueByAssetClass us-gaap:InvestmentsNANA0.6820.6920.5150.5150.5140.317NANA0.101NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:Goodwill ██████████████████████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁1299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541299.4541300.3791303.4531306.169359.759359.527353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396353.396354.831354.831354.831354.831353.734353.734353.734
us-gaap:IntangibleAssetsNetExcludingGoodwill ▆▆▇▇▇▇▇████▃▄▄▄▄▄▄▄▅▅▆▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▂▂▂▂▂11.35611.64911.94412.24212.53613.08313.26613.56613.86714.13614.3376.9547.1557.3577.5597.7657.9728.1828.3928.9449.16410.9573.383.443.2113.1213.1763.2313.2863.3423.3973.4533.5083.5653.623.6753.7313.7873.8433.8993.9554.0114.0694.1294.1894.248
us-gaap:OperatingLeaseRightOfUseAsset NANA4.188NANANA4.6294.8645.1615.331NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseRightOfUseAsset us-gaap:BalanceSheetLocation us-gaap:OtherNoncurrentAssetsNANA4.188NANANA4.629NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ██▇▄▄▄▃▄▆▅▂▃▃▂▁▁▂▁▁▂▂▁▃▄▅▅▅▅▆▅▅▄▄▄▃▃▃▃▃▃▃▃▃▃▄▃40.97138.88237.80124.31824.63324.25819.37625.33930.55225.82314.35217.14317.20714.810.14911.65513.81211.90512.1312.815.43811.27420.56622.13128.6728.2829.08629.9331.80828.92527.90622.11622.40221.36719.4219.8519.73321.13219.94120.89420.44220.90720.8620.21621.55918.064
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:AccountsPayableCurrent ▃▄▅▄▃▃▅▄▄▅▆▃▂▂▄▂▂▂▄▄▅▃▂▂▂▂▃▂▂▄▃▂▂▂▂▁▁▁▂▆▆▆█▆▆▅133.354160.179183.34152.01118.942136.344193.523145.085150.508178.678210.609115.9104.718106.281160.88795.59599.97105.074153.477141.78170.149121.684105.46891.63378.02188.77124.139100.444100.098149.681130.41677.07788.07182.43784.42269.13859.73959.793104.748219.167218.356217.559279.069201.072206.422194.342
us-gaap:AccruedLiabilitiesCurrent ▅▆▇▇▅▅▆▅▄▄▅▅▄▄▅▅▅▅▇▆▅█▆▆▂▃▃▃▂▂▂▂▁▁▂▃▂▂▂▃▂▂▃▃▁▂219.022230.444243.612244.01201.667203.445226.767217.832188.517196.072215.501201.353190.339194.04219.462213.571201.993203.467244.034228.522218.25272.181232.061229.957160.528166.781170.115163.374141.177145.973151.277152.911135.819140.23154.389179.284158.24151.13151.319168.64140.814141.184170.301166.977130.194140.939
us-gaap:LiabilitiesCurrent ▇▆▃▂▁▃▄▃▂▂▃▃▃▄▃▂▂▁▂▂█▃▁▂▁▁▃▃▃▁▁▃▃▃▃▄▄▂▄▄▄▄▄▃▃▃1230.5281229.599696.533513.932384.965719.854811.294691.124488.401591.015648.23730.23730.635788.564649.101554.27438.865391.542527.932480.821467.896660.262422.029448.757358.508379.114651.281727.043653.283399.735378.394704.633669.217681.593734.889898.946773.029556.703878.067889.431852.552756.14787.44639.049693.835671.959
us-gaap:LongTermDebtCurrent ▁▁▁▁▁▁▁▁▁▁▁▃▃▃▁▁▁▁▁▁█▁▁▁▁▁▃▃▃▁▁▃▃▂▂▃▃▁▁▁▁▁▁▁▁▁7.07.08.4369.8714.3075.7435.7435.7435.7435.7435.743255.743255.743255.7435.7435.7435.7435.7435.7435.743930.7430.00.00.00.00.0275.0275.0275.00.00.0255.694255.507104.637103.973328.31227.598.9772.4732.8933.6134.2545.1815.3144.53924.426
 us-gaap:OperatingLeaseLiabilityCurrent us-gaap:BalanceSheetLocation us-gaap:AccruedLiabilitiesNANA0.736NANANA1.179NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAccruedLiabilitiesCurrent ▅▄▅▅▄▃▄▄▄▄▅▅▅▆▇▆▇▇█▅▅▁▆█▅▆█31.19427.7434.99632.52328.23425.40930.83530.26228.14128.57332.43131.434.13837.1445.17241.6144.98743.0849.97334.94932.22311.67738.31849.78733.54239.08750.181NANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
 us-gaap:LongTermDebt us-gaap:FairValueByMeasurementBasis us-gaap:CarryingReportedAmountFairValueDisclosure█████▇▇▇▇▆▆▇▇▇▇▇▇▇▇▇▇▇▃▂▂▂▂▂▂▂▂▁▁▁▁▂▂3537.2163536.1583536.5363536.7653537.1943142.633145.8393054.9783055.4152956.0422956.5783207.1323113.8113114.533115.1433115.6073166.0453216.4733216.9323217.5113152.093159.0551866.8661567.7971567.7271542.6581542.5891382.5191396.951396.9491396.9481211.6731214.0661041.1141042.851271.261272.481NANANANANANANANANA
us-gaap:LongTermDebtNoncurrent █████▇▇▇▇▆▆▆▆▆▇▇▇▇▇▇▄▇▄▃▃▃▂▁▂▂▂▁▁▁▁▁▁▂▂▂▂▂▂▂▁▁3530.2163529.1583528.13526.8943532.8873136.8873140.0963049.2353049.6722950.2992950.8352951.3892858.0682858.7873109.43109.8643160.3023210.733211.1893211.7682221.3473159.0551866.8661567.7971567.7271542.6581267.5891107.5191121.951396.9491396.948955.979958.559936.477938.877942.951044.8911272.0161280.4091282.1941183.5831184.831186.051188.293990.13993.514
us-gaap:DeferredFinanceCostsNoncurrentNet NANA24.809NANANANANANANANANANANA18.478NANANA21.822NANANA11.379NANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet █▇▅▄▄▄▁436.495428.127408.624398.136388.962387.939360.719NANANA311.331NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent ▅▅▅▄▄▅▅▃▅▅▅▅▆▆▆▅▇▇▇▇▇█▅▆▇▆▆▁▂▁▁▇█▇▇▇▆▆█▂▃▃▃▂▅▄151.29150.979150.556144.049142.58152.693154.472134.15146.648145.883145.147151.613162.199160.58159.646149.803176.102174.827173.682171.633173.347181.27146.459158.614165.791162.334158.966108.924116.403113.324111.479169.448177.216172.353167.397167.69162.53157.623177.48124.214131.169128.17124.709122.178148.19144.199
us-gaap:OtherLiabilitiesNoncurrent ▅▅▅▃▃▃▄▃▃▃▂▁▁▁▁▅▅▅▆▆▃▄█▅███▆▆▄▅▅▄▄▄▄▄▄▄▄▄▅▄▄▂▂133.021135.224134.667120.522119.649122.869124.662120.82118.613118.007109.377105.928104.951105.221105.735137.251135.51135.847138.643141.007122.015124.181155.369136.462154.656154.604154.406144.089137.765129.083133.279133.341129.763125.958125.294129.63124.482123.848123.553128.013124.941134.617129.932125.71115.656114.021
 us-gaap:OperatingLeaseLiabilityNoncurrent us-gaap:BalanceSheetLocation us-gaap:OtherNoncurrentLiabilitiesNANA3.807NANANA3.821NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA0.804NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA0.779NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA0.776NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA0.529NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA1.643NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:StockholdersEquity ███▇▇▇▆▆▆▆▆▄▄▄▃▃▃▃▃▃▂▂▂▁▁2659.042624.5132561.3852519.0462513.2922523.1682362.1232329.4782316.752279.1592181.5881813.2551818.8461818.771708.9741682.8041676.2391674.3161614.6391604.6421562.4271480.6831465.8671287.2121310.886NA1376.024NANANA1307.748NANANA1232.5091214.3171196.2851224.6921209.3361088.0051108.0691113.1471100.271080.4071082.3831107.998
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest ███▇▇▇▇▇▆▆▆▄▄▄▄▄▄▄▃▃▃▂▂▁▂▂▂▂▂▂▁▁▁▁▁▁▁▁2758.8942725.3022662.6472620.22614.4962624.4232464.0692432.8962419.9982383.7022287.4231921.1791926.5331927.9841820.2061795.9821790.0311788.9781730.1341722.0241679.9451480.6831465.8671287.2121310.8861407.7671376.0241357.3921341.3251337.4191307.7481290.9491282.6881260.8931232.5091214.3171196.2851224.692NANANANANANANANA
us-gaap:CommonStockValue ██████▇▇▇▇▇▅▅▅▅▅▅▅▅▅▅▅▄▃▃▃▃▃▃▃▃▃▃▃▂▂▂▂▂▁▁▁▁▁▁▁63.52762.9162.82762.77362.77362.77361.48161.48161.09160.37860.04953.66253.66253.64953.5853.52553.51453.50253.39753.13152.29951.47751.23244.89244.87244.85744.71444.69744.68344.66744.5544.53244.51744.48244.27844.25144.17744.15143.95839.49239.46239.43439.2839.24339.20439.178
us-gaap:AdditionalPaidInCapital ██████▇▇▇▆▆▄▄▄▄▄▄▄▄▄▃▃▃▁▁▁▁▁▁▁▁1701.8251658.9571657.2851655.9121654.5631652.8611552.7881553.191522.2081469.411450.5691157.2141154.9471151.9331150.2851147.9221145.4931143.1021138.9821123.5271072.927960.605953.044753.856751.679749.517748.84746.575744.505742.016742.344NANANA733.095731.176727.613725.512722.623604.945602.961601.021598.805597.108595.219593.589
us-gaap:RetainedEarningsAccumulatedDeficit ██▇▆▆▇▆▅▅▆▅▄▄▄▂▂▂▂▁▁▁▁▁▂▂▄▃▃▃▃▂▂▂▂▂▁▁▁▁▁▁▂▁▁▁▁921.122931.538870.738828.993826.269838.841778.776742.138761.222777.262700.396644.154652.642656.161548.617516.371512.498513.885457.934462.09469.94490.999472.534504.864532.965629.135599.389582.8573.379570.963540.244539.03532.81519.184492.869478.459460.324490.114476.603467.043491.208498.614486.075466.691468.43491.202
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▅▄▄▄▄▄▃▄▄▄▄▂▂▁▁▃▃▃▂▃▃▅█▇▆▇▇▇▆▆▆▃▃▂▂▂▃▃▃▅▅▄▅▅▆▇-24.446-26.328-27.346-26.922-28.434-29.382-30.655-25.695-26.227-26.459-26.916-37.703-38.763-39.924-41.202-32.566-32.941-33.73-34.883-32.951-31.764-20.825-9.055-14.611-16.859-14.054-15.044-14.839-19.441-18.589-17.422-31.021-30.781-36.224-35.488-37.215-33.652-33.044-32.878-22.665-24.871-25.16-23.581-22.409-20.443-15.859
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:DerivativeInstrumentRisk,us-gaap:StatementEquityComponents us-gaap:CommodityContract,us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges▂▁▁▂▁▁▁▁▁▁▂▁▁▁▁▁▂▁▁▂▃▅▆▆▅▇█1.0290.1320.0020.287-0.252-0.26-0.456-0.372-0.3810.0820.328-0.071-0.122-0.27-0.518-0.0680.2580.17-0.2330.2531.9715.5467.0666.9065.5389.26810.023NANANA-0.508NANANA0.6NANANA4.338NANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:DerivativeInstrumentRisk,us-gaap:StatementEquityComponents us-gaap:InterestRateSwap,us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges▄▄▄▃▃▃▃▂▂▂▂▂▁▁▁▂▂▂▂▁▁▄█▇▇▇▆-11.472-12.035-12.558-13.492-14.035-14.579-15.122-15.668-16.216-16.757-17.307-17.884-18.444-19.005-19.581-16.66-17.124-17.588-18.109-18.282-18.526-10.877-0.341-2.62-3.077-3.58-4.93NANANA-6.625NANANA-16.313NANANA-18.14NANANANANANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment▆▅▅▆▆▅▅████▃▂▂▂▅▅▄▄▅▅▅▅▁▁▃▂████-14.003-14.425-14.79-13.717-14.147-14.543-15.077-9.655-9.63-9.784-9.937-19.748-20.197-20.649-21.103-15.838-16.075-16.312-16.541-14.922-15.209-15.494-15.78-22.546-22.969-19.742-20.137-10.145-10.274-9.978-10.289NANANA-19.775NANANA-19.076NANANANANANANA
us-gaap:TreasuryStockValue ▆▅▅▄▄▄▁▄▄▃▅█▇▆▅▅▅▅▂▃▃▄▄▄▄▄▄▄▄▄▄▄▄▄▅▅▅▄▃▂▂▂▁▁▁▁2.9882.5642.1191.711.8791.9250.2671.6361.5441.4322.514.0723.6423.0492.3062.4482.3252.4430.7911.1550.9751.5731.8881.7891.7711.6881.8751.8411.8011.6381.9681.8011.5871.5492.2452.3542.1772.0410.970.810.6910.7620.3090.2260.0270.112
us-gaap:StockIssuedDuringPeriodValueNewIssues 40.232NANANANA100.0NA30.00150.00119.999NANANA0.0NA0.0NANA14.75249.43648.9786.824254.5810.00.00.0NANANANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders ▁█4.0614.644NA4.1163.7794.741NA3.4854.4054.8465.8623.7574.355.6486.5084.5493.9864.3495.045NANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇▁▇▇▇█▇▇▇█▇▆▇█▇▆▇▇▇▆▇▇▆▇▇█▇▆▇▇▇▆▇▇▆▇▇▇▆▆▇▇▆▅▆▇135.913-386.086122.404110.453117.037191.969119.43896.296113.886175.893110.08968.021140.826169.875108.83156.561116.029146.8495.7861.90284.438138.33762.131111.465102.921151.48784.365.32275.73798.09872.86354.38188.153109.23247.30492.96880.63496.06517.17724.5170.746111.27121.991-18.22955.07188.919
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▇▆▆▆▆▆▆▆▇▆▇▇▇▇▇▇▇▇▇▇▁▇▇▇▇▇▇▇▇▇▇▇▇▇█▇█▇▇▇▇▇▇▇▇-163.513-146.224-231.94-179.999-176.641-173.084-222.938-275.975-172.27-145.027-184.078-118.245-89.972-73.554-61.276-92.598-94.296-69.494-129.546-134.455-108.209-1216.532-119.729-149.536-89.253-117.871-130.826-90.025-93.467-86.829-112.639-91.415-82.315-62.909-87.137135.005-78.16541.466-120.145-101.798-103.306-121.758-135.413-90.734-84.971-78.05
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▇▃▃▃▃▃▄▃▂▃▃▂▂▂▃▂▂▃▃▃█▆▂▃▃▃▃▃▃▃▃▃▂▁▂▂▁▃▃▃▃▃▃▂▃15.409539.496109.06345.04537.15325.621100.383186.2152.909-39.29284.89251.752-73.045-80.656-45.58337.957-21.496-79.5730.0578.71293.602668.634475.292-10.29810.1578.55155.80521.94514.786-1.46933.9820.03812.398-49.388-191.897-20.891-18.491-140.16786.95763.99476.61722.06586.885103.905-42.0912.253
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DeferredIncomeTaxExpenseBenefit ▄▄▅▄▄▆▅▄▄▆▃▅▄▁▅▅▅█▄▄▄▇▃▂▁▆▆▅▅▆▅▆▅▆▅▆▃▆▅▃▄▆▃█▃▄0.5390.1539.5892.1014.52521.87613.6392.4462.33319.602-9.8437.0234.011-25.4316.3213.5198.95842.195-2.3615.9720.02732.579-5.22-14.531-28.32522.04820.99512.4939.56125.9538.91918.25816.06620.54110.99817.518-6.88318.0837.32-5.4296.0325.679-13.1638.444-9.573.492
us-gaap:DepreciationDepletionAndAmortization ██▇███▇▆▆▆▆▆▆▆▄▆▆▆▆▆▅▅▃▃▄▄▃▃▃▃▃▃▃▂▂▄▄▃▃▂▂▂▃▁▁▁58.44357.26955.04456.34856.66356.40254.61351.88451.59551.02849.98349.04648.70948.5941.50249.43448.66348.64748.40648.92547.30544.40738.54937.76840.05139.58637.82537.46336.71236.08335.14936.13535.15234.78133.23441.40841.43138.55937.89633.37432.33431.98738.20330.03630.2628.395
us-gaap:IncreaseDecreaseInInventories ▆▅▅▇▆▄▅▇▆▄▅▇▆▄▅▇▆▄▅▇▆▄▅▇▆▄▅▇▆▄▅▇▆▅▅▇▅▄█▇█▁▅▇█▄11.958-15.932-13.6618.40811.719-19.222-6.17819.03714.476-29.387-5.46126.87212.704-31.196-9.47127.2814.725-22.445-6.26522.8888.1-25.822-3.57916.65.471-25.689-12.68524.56214.977-22.291-6.75221.4629.579-18.519-3.25819.524-1.781-20.82833.97729.95537.17-79.717-15.07920.44841.651-21.755
us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet ▅▄▃▃▄▄▃▁▆▃▂▂▄▄▆▄▃▅▁▅▂▇▅█▂▄▅▄▂▃▆▂▂▆▆▂▆▄█▂█▂▇▁▁▆2.4790.355-3.145-2.660.0141.138-2.694-6.1684.657-1.796-4.682-3.3791.0940.2785.4660.897-1.1473.202-6.7733.114-4.6057.4892.6319.618-4.8731.6583.3541.771-3.88-1.9784.447-5.353-4.2984.8925.665-3.6715.348-0.6110.427-5.4510.754-4.6139.177-6.111-6.9895.335
us-gaap:NetCashProvidedByUsedInOperatingActivities ▇▁▇▇▇█▇▇▇█▇▆▇█▇▆▇▇▇▆▇▇▆▇▇█▇▆▇▇▇▆▇▇▆▇▇▇▆▆▇▇▆▅▆▇135.913-386.086122.404110.453117.037191.969119.43896.296113.886175.893110.08968.021140.826169.875108.83156.561116.029146.8495.7861.90284.438138.33762.131111.465102.921151.48784.365.32275.73798.09872.86354.38188.153109.23247.30492.96880.63496.06517.17724.5170.746111.27121.991-18.22955.07188.919
us-gaap:NetIncomeLoss ▂▆▅▂▂▆▄▁▁▆▅▁▂█25.16196.31677.18536.28320.96693.17469.17911.7414.583103.80886.57116.9521.917133.004NANANANANANANANANANANANANANANANANANANANA30.76734.457-13.48329.78725.593-10.5257.75226.9133.5212.39-8.65931.434
us-gaap:ProfitLoss ▄▇▆▄▄▆▅▃▃▇▆▃▄█▅▄▄▆▃▃▃▄▂▂▁▄28.287100.48780.49640.34924.69497.22472.87215.39517.693107.36290.34420.94424.74136.63454.22131.59825.31180.14621.41417.8843.28340.05-14.176-9.943-41.84233.85NANANANANANA30.51843.19730.76734.457-13.48329.78725.593-10.5257.75226.91NANANA31.434
us-gaap:ShareBasedCompensation ▄▆▅▄▂▂▇▃▇▆█▅▅▄▁▃▆▆▄▄▅▇▃▁▃▄▅▁▆▆▆▄▆▇▄▅▃▄▂▄▃▅▅▃▃▃1.7873.2572.6771.5830.8220.2913.7631.2393.7973.2964.8462.3233.0122.2090.0321.0053.4983.0911.7612.072.5934.4611.208-0.231.0152.0832.3510.073.1923.7163.4952.2043.1183.7782.2972.7051.4521.8170.7121.6720.8892.372.9410.9370.9820.989
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInInvestingActivities ▆▇▆▆▆▆▆▆▆▇▆▇▇▇▇▇▇▇▇▇▇▁▇▇▇▇▇▇▇▇▇▇▇▇▇█▇█▇▇▇▇▇▇▇▇-163.513-146.224-231.94-179.999-176.641-173.084-222.938-275.975-172.27-145.027-184.078-118.245-89.972-73.554-61.276-92.598-94.296-69.494-129.546-134.455-108.209-1216.532-119.729-149.536-89.253-117.871-130.826-90.025-93.467-86.829-112.639-91.415-82.315-62.909-87.137135.005-78.16541.466-120.145-101.798-103.306-121.758-135.413-90.734-84.971-78.05
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▅▄▇▅▅▅▆█▅▄▅▃▂▁▁▂▂▁▄▃▃▂▂▄▂▃▂▃▂▂▃▂▂▁▂▃▂▁173.174146.302231.411187.68176.431171.882225.839274.851173.56144.126179.392121.38486.77669.97269.87292.3794.45969.309140.685134.244115.96983.885106.01142.99988.949117.523108.195112.99793.69383.609115.26492.25583.29163.93987.715112.60781.15567.652NANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:NetCashProvidedByUsedInFinancingActivities ▃▇▃▃▃▃▃▄▃▂▃▃▂▂▂▃▂▂▃▃▃█▆▂▃▃▃▃▃▃▃▃▃▂▁▂▂▁▃▃▃▃▃▃▂▃15.409539.496109.06345.04537.15325.621100.383186.2152.909-39.29284.89251.752-73.045-80.656-45.58337.957-21.496-79.5730.0578.71293.602668.634475.292-10.29810.1578.55155.80521.94514.786-1.46933.9820.03812.398-49.388-191.897-20.891-18.491-140.16786.95763.99476.61722.06586.885103.905-42.0912.253
us-gaap:ProceedsFromIssuanceOfLongTermDebt NANA0.00.0NANA700.00.0NANA0.0700.0NANA0.00.00.00.00.01192.93628.713545.9590.00.0300.00.0160.00.0NANA525.00.0NANA0.00.0NANA0.0NANANA0.0NANANA
us-gaap:RepaymentsOfLongTermDebt ▁▁▁▁▁▁▅▁▃▁▃▅▁▁▁▁▁▁▁█▁▁▁▁0.01.4361.4341.4361.4364.291601.4361.436301.4351.436251.436600.4361.4351.4361.43651.43651.4351.4361.4361121.43641.4360.00.00.0NANA0.012.20.00.0339.7262.394102.0491.737228.431.2298.5211.8972.2132.1171.8972.1552.3761.06223.27133.217
us-gaap:PaymentsOfDividends ███▇▇▇▇▆▆▆▆▅▅▅▅▄▄▄▄▄▄▄▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▁▁▁▁▁▁▁35.57835.51435.4433.55933.53832.90232.86830.82730.6230.33230.28225.4325.43525.44425.4123.7923.7923.75422.32321.98221.72821.53718.15418.15818.14418.14817.41817.41517.40417.39916.90916.90416.89216.88216.35816.32116.30716.27616.03313.63915.15914.37114.13614.12914.11314.089
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value6362626262626161616060535353535353535353525151444444444444444444444444444444433939393939393938
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.80.80.80.80.80.80.90.90.90.80.80.80.80.80.80.80.80.80.80.81.11.11.11.01.01.11.11.11.11.21.21.21.21.11.21.21.11.01.01.11.11.11.21.21.2

Common Stock Par Or Stated Value Per Share

us-gaap:CommonStockParOrStatedValuePerShare

us-gaap:CommonStockParOrStatedValuePerShare


Common
Period End2020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value1.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01.01000.01.01.01.01.01.01.01.01.01.0
Percentage of CommonStockParOrStatedValuePerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesAuthorized


Common
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100100000100000100100100100100100100100
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value6262626261616060545454555554535251444444444444444444444343393939393839
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-302010-03-31
Value6262626261606059535353535353525151444444444444444444434343393939383838
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount


Antidilutive
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-09-302010-06-30
Value13000.033000.071000.0105000.038000.02000.006000.012000.015000.071000.00002000.04000.074000.0121000.0119000.0107000.099000.081000.046000.0028000.040000.0138000.0207000.0174000.0223000.0157000.090000.0131000.0309000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount us-gaap:AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecurities

us-gaap:RestrictedStock


Antidilutive
Period End2021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302010-09-302010-06-30
Value19000.049000.076000.026000.00000018000.034000.061000.066000.031000.020000.024000.02000.0108000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount57.669.072.468.40.00.00.00.00.064.385.044.231.917.89.015.31.535.0

us-gaap:StockCompensationPlan


Antidilutive
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value13000.014000.022000.029000.012000.02000.006000.012000.015000.071000.00002000.04000.074000.0121000.0119000.0107000.099000.081000.046000.0028000.040000.0
Percentage of AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount100.042.431.027.631.6100.00.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.41.541.240.580.341.511.130.190.241.731.50.320.412.490.950.520.421.440.340.270.010.78-0.3-0.22-0.941.080.770.60.451.090.410.520.690.980.70.79-0.310.680.61-0.270.20.690.860.32-0.220.81
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.41.541.240.580.331.511.130.190.241.731.490.310.42.460.920.50.41.390.330.260.010.77-0.3-0.22-0.941.070.760.60.441.080.410.520.690.970.70.78-0.310.680.6-0.270.190.680.850.32-0.220.81
Percentage of EarningsPerShareDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Comprehensive Income Net Of Tax

us-gaap:ComprehensiveIncomeNetOfTax

us-gaap:ComprehensiveIncomeNetOfTax


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312011-12-312011-09-302011-06-302010-12-312010-09-302010-06-30
Value279776372194641214104901823134492822771612-10.2728-8.62-7.695-44.64734-34.35-8.3188.04-36.33710-13.243
Percentage of ComprehensiveIncomeNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.315.40.011.06.817.813.43.84.517.418.05.66.523.410.88.46.714.23.53.9-3.26.3-2.7-2.8-16.47.9-9.5-3.22.9-11.54.2-5.2

Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value3010180412598671517107932225137523126811916-7.65628-8.62-7.695-44.64748333118463122354283-3.563-0.608-0.166-10.2132.2070.288-1.579
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.216.10.012.27.918.614.24.95.418.018.76.97.324.111.59.57.614.84.25.0-2.46.3-2.7-2.8-16.411.18.911.66.710.28.98.812.911.226.1-1.4-0.3-0.0-2.80.90.1-0.4

Cost Of Goods And Services Sold

us-gaap:CostOfGoodsAndServicesSold

us-gaap:CostOfGoodsAndServicesSold


Cost
Period End2020-09-302019-09-30
Value7173
Percentage of CostOfGoodsAndServicesSold100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax20.822.7

us-gaap:CostOfGoodsAndServicesSold us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:CommodityContract, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Cost
Period End2020-09-302019-09-30
Value-0.178-0.129
Percentage of CostOfGoodsAndServicesSold-0.2-0.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CommodityContract us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.0

Costs And Expenses

us-gaap:CostsAndExpenses

us-gaap:CostsAndExpenses


Costs
Period End2020-12-312020-09-302019-12-312019-09-302011-03-312010-03-31
Value-356.425264-423.6542542922
Percentage of CostsAndExpenses100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.076.8-88.778.87.35.5

Income Loss From Continuing Operations Before Income Taxes Minority Interest And Income Loss From Equity Method Investments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2810087452911380172012479293311387453511320243.59244-22.461-21.978-56.9427352383073303646644952-19.9195524-18.72712384811-15.09347
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.816.00.013.19.121.416.85.56.120.815.99.19.619.719.113.510.420.74.57.31.19.8-7.1-8.1-20.916.613.814.010.816.08.514.016.517.015.421.3-8.215.06.8-7.34.79.715.54.4-5.911.4

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.573-0.573-0.572-0.573-0.572-0.567-0.202-0.064-0.201-0.201-0.577-0.577-0.578-0.577-0.364-0.365-0.365-0.366-3.0740.4390.4390.4390.6340.6510.650.650.20.1980.150.2290.6370.6370.6320.632
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments-2.0-0.6-0.7-1.3-1.9-0.5-0.3-0.4-1.0-0.2-0.7-2.0-1.7-0.5-0.4-0.8-1.0-0.3-14.91.812.21.0-2.8-3.0-1.10.90.40.50.50.32.11.71.41.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.2-0.10.0-0.2-0.2-0.1-0.0-0.0-0.1-0.0-0.1-0.2-0.2-0.1-0.1-0.1-0.1-0.1-0.70.10.10.10.20.20.20.10.10.10.10.00.20.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.657-0.744-0.58-0.89-0.783-1.199-0.803-0.842-0.63-0.159-0.041-0.73-0.876-1.334-0.977-0.452-0.327-0.42513-1.489-2.386-5.358-4.815-1.506-1.996-2.4950.2222.062.1771.2051.4982.0121.8480.704
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments-2.3-0.7-0.7-2.0-2.7-1.1-1.0-4.7-3.1-0.1-0.1-2.5-2.6-1.2-1.1-1.0-0.9-0.466.2-6.1-66.4-12.121.46.93.5-3.40.45.47.11.65.05.54.01.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.2-0.10.0-0.3-0.2-0.2-0.2-0.3-0.2-0.0-0.0-0.2-0.2-0.2-0.2-0.1-0.1-0.13.0-0.4-0.7-1.2-1.5-0.6-0.7-0.60.10.80.80.30.40.80.70.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.5860.4947.4344.6514.831167.5022.5082.30717-11.8837.4776.541-25.80215131033-0.736.6440.3094.252-7.52-12.035-20.3172518111025111315211817-7.574198.43-8.1595.0441215-1.461-5.14316
Percentage of IncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.01.41.53.01.60.80.72.9-2.42.31.9-4.53.54.13.06.1-0.22.00.10.9-2.4-4.4-7.55.74.84.23.85.53.15.15.65.75.87.3-3.15.42.3-3.21.83.24.9-0.6-2.04.0

us-gaap:IncomeTaxExpenseBenefit us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustment


Income
Period End2020-12-31
Value0.0
Percentage of IncomeTaxExpenseBenefit0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:CumulativeEffectPeriodOfAdoptionAdjustment0.0

us-gaap:IncomeTaxExpenseBenefit us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.151-0.208-0.528-0.143-0.176-0.0880.637-0.089-0.047-0.048-0.163-0.128-0.126-0.1260.909-0.128-0.128-0.137-0.9920.1520.1540.1530.20.2280.2280.2280.070.0690.0520.0810.220.220.2680.175
Percentage of IncomeTaxExpenseBenefit-25.8-42.1-7.1-3.1-3.6-0.58.5-3.5-2.0-0.31.4-1.7-1.90.55.8-0.9-1.2-0.4135.92.349.83.6-2.7-1.9-1.10.90.40.60.50.32.01.61.70.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.00.0-0.0-0.1-0.00.1-0.0-0.0-0.0-0.0-0.0-0.0-0.00.2-0.0-0.0-0.0-0.20.00.00.00.10.10.10.10.00.00.00.00.10.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.136-0.1980.297-0.209-0.186-0.285-0.253-0.17-0.153-0.0350.013-0.149-0.197-0.297-0.44-0.154-0.106-0.1435.152-0.566-0.882-1.946-1.723-0.558-0.735-1.2540.4130.7320.7740.4250.5470.5860.6470.236
Percentage of IncomeTaxExpenseBenefit-23.2-40.14.0-4.5-3.9-1.8-3.4-6.8-6.6-0.2-0.1-2.0-3.01.2-2.8-1.1-1.0-0.4-705.8-8.5-285.4-45.822.94.63.6-5.02.36.57.31.74.94.44.11.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.00.0-0.1-0.1-0.1-0.1-0.1-0.0-0.00.0-0.0-0.1-0.1-0.1-0.0-0.0-0.01.1-0.2-0.3-0.4-0.5-0.2-0.3-0.30.10.30.30.10.20.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Income Taxes Paid Net

us-gaap:IncomeTaxesPaidNet

us-gaap:IncomeTaxesPaidNet


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-0.496-0.99-0.9160.64-1.8960.0-2.427-0.465-1.782-0.008-0.1120.0050.50114-1.7740.00.012-0.013-0.0120.0061.1620.00.00.01.20.0020.0170.00.4-0.004-0.351-0.4820.754.6563.452-0.808-1.4551.8381.972-1.188-10.59-0.048-9.8720.089
Percentage of IncomeTaxesPaidNet100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.20.00.2-0.60.0-0.5-0.1-0.5-0.0-0.00.00.12.5-0.40.00.0-0.0-0.00.00.40.00.00.00.40.00.00.00.1-0.0-0.1-0.20.31.21.1-0.3-0.60.50.5-0.5-3.9-0.0-3.10.0

Interest Income Expense Net

us-gaap:InterestIncomeExpenseNet

us-gaap:InterestIncomeExpenseNet


Interest
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-38202000.0-37600000.0-36041000.0-35545000.0-35453000.0-33487000.0-34265000.0-34717000.0-35297000.0-34534000.0-34995000.0
Percentage of InterestIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-10.4-6.0-10.5-11.0-6.7-10.3-10.4-5.8-11.0-9.8-6.1

Interest Paid Net

us-gaap:InterestPaidNet

us-gaap:InterestPaidNet


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value5021492045213231363033363036303629363034321528122610231123115112311246143816411138113935
Percentage of InterestPaidNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.73.40.05.814.14.16.89.811.25.16.811.58.66.46.710.78.66.66.510.310.03.58.84.49.82.56.14.18.32.514.45.011.23.414.65.915.94.611.54.514.02.912.414.4

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2596773620936911141038616211333034-13.4832925-10.5257.752263312-8.65931
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.815.30.010.56.517.614.53.64.417.417.35.36.223.29.614.0-5.68.17.1-4.12.86.710.65.0-3.47.5

us-gaap:NetIncomeLoss us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustment


Net
Period End2020-12-31
Value0.0
Percentage of NetIncomeLoss0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:CumulativeEffectPeriodOfAdoptionAdjustment0.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-30
Value3.1264.1713.3114.0663.7284.053.6933.6553.113.5543.7733.9942.8233.633.5683.9353.1163.6233.2463.7532.6140.0480.00.00.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.80.70.01.21.10.80.81.10.90.60.81.20.80.60.81.20.90.70.71.10.80.00.00.00.0

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic


Net
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value36209311141038616211335027227618140.66940-14.176-9.943-41.8424734261948182330433034-13.48329
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax10.56.517.63.64.417.417.35.36.223.211.18.26.514.03.94.20.28.9-4.5-3.7-15.410.89.09.97.010.55.18.910.911.39.614.0-5.68.1

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302011-03-312010-03-31
Value-38.393-37.334-38.021-37.234-37.408-39.959116-52.648-34.001-35.506105-35.807-35.843-35.099102-33.116-33.217-34.08399-33.881-16.887-22.109
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-10.4-5.90.0-10.8-11.5-7.524.4-16.3-10.3-5.921.1-11.2-10.2-6.122.5-9.9-9.7-6.221.4-10.2-4.2-5.3

Operating Expenses

us-gaap:OperatingExpenses

us-gaap:OperatingExpenses


Operating
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value305495259383356254279437387256286427314263279406408275290376318274311350308217236370284204230300243168221295292215230347329201225356
Percentage of OperatingExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax82.978.680.272.474.678.884.973.277.280.281.274.569.078.581.774.288.182.589.283.699.9100.8114.379.281.580.083.680.580.078.682.579.076.468.591.580.981.183.884.486.7104.680.888.085.6

Operating Income Loss

us-gaap:OperatingIncomeLoss

us-gaap:OperatingIncomeLoss


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value671381258266153121705416011465691481177868147555835730.197-2.044-38.858916954468971554979757720705241425546473069
Percentage of OperatingIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax18.321.90.023.920.628.925.421.816.426.822.820.319.725.925.723.420.126.911.917.510.816.40.1-0.8-14.320.818.520.016.419.520.021.417.521.023.631.58.519.114.416.215.613.914.919.212.016.7

us-gaap:OperatingIncomeLoss us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Operating
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-0.181-3.122-0.239-0.0290.16-0.0340.102-0.50736-0.178-0.836-1.696
Percentage of OperatingIncomeLoss-0.3-2.3-0.3-0.00.1-0.00.2-0.332.0-0.3-1.2-1.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.5-0.1-0.00.0-0.00.0-0.17.3-0.1-0.2-0.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateNonSegment0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingIncomeLoss us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Operating
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value352152333550334126434138
Percentage of OperatingIncomeLoss52.915.863.350.823.371.862.125.623.266.759.226.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax9.73.515.110.56.715.610.26.95.313.611.76.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ElectricUtilities19.59.626.021.020.526.520.422.50.023.524.022.2

bkh:GasUtilities


Operating
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1910218181024.7368.557103694.241695
Percentage of OperatingIncomeLoss29.773.822.127.267.26.715.864.560.56.523.764.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax5.416.25.35.619.41.52.617.313.81.34.716.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:GasUtilities10.825.512.711.329.03.65.225.10.03.29.324.1

bkh:Mining


Operating
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.6443.2613.5053.3583.1293.3741.644.3373.6934.5513.8254.271
Percentage of OperatingIncomeLoss5.42.44.35.02.04.83.02.73.27.05.52.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.00.51.01.00.61.00.50.70.71.41.10.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Mining26.323.223.922.621.722.513.227.40.027.223.425.8

bkh:PowerGeneration


Operating
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8.25148.738111111101114138.87711
Percentage of OperatingIncomeLoss12.310.310.617.07.416.818.87.512.820.112.87.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.22.32.53.52.13.73.12.02.94.12.52.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:PowerGeneration33.149.733.544.344.673.367.477.40.090.369.784.5

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-30
Value1.8821.018-0.4241.5120.9481.273-4.960.5320.2320.4573.5461.061.1611.26-1.6360.3750.7891.153-1.932-1.187-10.939-11.775.5562.248-2.8050.99-0.2054.602-0.852-1.16713-0.245.443-0.736-49.03430-0.608-0.166-34.35-8.318
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.20.00.40.30.2-1.00.20.10.10.70.30.30.2-0.40.10.20.2-0.4-0.4-3.4-2.61.70.8-1.00.2-0.11.7-0.3-0.33.8-0.11.9-0.2-15.412.5-0.3-0.0-9.5-3.2

us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value1.8821.0181.5120.9481.2730.5320.2320.4571.061.1611.26
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.20.40.30.20.20.10.10.30.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.0

Other Nonoperating Income Expense

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:OtherNonoperatingIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-0.1910.266-1.59-1.193-1.8632.353-5.7810.2690.137-0.8370.627-0.703-1.551-0.1722.0790.189-0.058-0.1023.7020.16-0.0470.6880.8690.8420.3950.3311.4190.2610.4090.5920.6010.3180.4740.4050.892-0.2870.8881.4721.9650.5240.5060.7314.9230.5391.2680.418
Percentage of OtherNonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.10.00.0-0.3-0.60.4-1.20.10.0-0.10.1-0.2-0.4-0.00.50.1-0.0-0.00.80.0-0.00.20.30.30.10.10.40.10.10.10.20.10.20.10.3-0.10.40.40.50.20.20.21.60.20.50.1

us-gaap:OtherNonoperatingIncomeExpense us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustment


Other
Period End2020-12-31
Value0.0
Percentage of OtherNonoperatingIncomeExpense-0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:CumulativeEffectPeriodOfAdoptionAdjustment0.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value28100804024977215171079020241365431258021173.28340-14.176-9.943-41.8423330433034-13.4832925-10.5257.7522631
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.715.90.011.77.618.315.34.85.418.018.06.57.023.811.99.47.414.64.65.41.08.9-4.5-3.7-15.47.710.911.39.614.0-5.68.17.1-4.12.86.77.5

us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-0.943-0.911-0.921-1.111-0.993-1.393-1.389-0.647-0.631-0.277-0.468-1.03-1.131-1.488-1.81-0.535-0.458-0.511-0.0990.6361.2193.126
Percentage of ProfitLoss-3.3-0.9-1.1-2.8-4.0-1.4-1.9-4.2-3.6-0.3-0.5-4.9-4.6-1.1-3.3-1.7-1.8-0.6-0.53.637.17.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.3-0.10.0-0.3-0.3-0.3-0.3-0.2-0.2-0.0-0.1-0.3-0.3-0.3-0.4-0.2-0.1-0.1-0.00.20.40.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.422-0.365-0.044-0.43-0.396-0.479-0.8390.025-0.154-0.153-0.414-0.449-0.452-0.451-1.273-0.237-0.237-0.229-0.366-0.287-0.2850.2860.4340.4230.4220.4220.130.1290.0980.1480.4170.4170.3640.457
Percentage of ProfitLoss-1.5-0.4-0.1-1.1-1.6-0.5-1.20.2-0.9-0.1-0.5-2.1-1.8-0.3-2.3-0.8-0.9-0.3-1.7-1.6-8.70.7-3.1-4.3-1.01.20.00.00.00.00.00.01.21.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.10.0-0.1-0.1-0.1-0.20.0-0.0-0.0-0.1-0.1-0.1-0.1-0.3-0.1-0.1-0.0-0.1-0.1-0.10.10.10.20.20.10.00.00.00.00.10.20.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.521-0.546-0.877-0.681-0.597-0.914-0.55-0.672-0.477-0.124-0.054-0.581-0.679-1.037-0.537-0.298-0.221-0.2820.2670.9231.504-3.412-3.092-0.948-1.261-1.241-0.1911.3281.4030.780.9511.4261.2010.468
Percentage of ProfitLoss-1.8-0.5-1.1-1.7-2.4-0.9-0.8-4.4-2.7-0.1-0.1-2.8-2.7-0.8-1.0-0.9-0.9-0.41.25.245.8-8.521.89.53.0-3.70.00.00.00.00.00.03.91.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.10.0-0.2-0.2-0.2-0.1-0.2-0.1-0.0-0.0-0.2-0.2-0.2-0.1-0.1-0.1-0.10.10.30.5-0.8-1.0-0.3-0.5-0.3-0.10.50.50.20.30.50.40.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value3.1264.1714.0663.7284.053.6553.113.554
Percentage of ProfitLoss11.14.210.115.14.223.717.63.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.80.71.21.10.81.10.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value25963620931114103
Percentage of ProfitLoss88.995.889.984.995.876.382.496.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.815.310.56.517.63.64.417.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.0

Revenue From Contract With Customer Excluding Assessed Tax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value368630482344324530477323329597501320352573455335341547463333325449318272272441378272283460355259279380318246242365361256273400314249256416
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-37.703-39.848-40.202-39.899-38.542-38.642-66.409-28.449-26.147-28.2-24.923-26.297-25.197-26.617
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-10.2-6.3-8.3-11.6-11.9-7.3-13.9-8.8-7.9-4.7-5.0-8.2-7.1-4.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-10.2-6.3-8.3-11.6-11.9-7.3-13.9-8.8-7.9-4.7-5.0-8.2-7.1-4.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:MajorCustomers

us-gaap:IntersegmentElimination, bkh:MarketOffSystemSales


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-1.675-2.884-2.674-1.904-1.58-2.639-2.689-1.488-1.335-2.224-2.571-1.349-1.66-2.522
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.5-0.5-0.6-0.6-0.5-0.5-0.6-0.5-0.4-0.4-0.5-0.4-0.5-0.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.5-0.5-0.6-0.6-0.5-0.5-0.6-0.5-0.4-0.4-0.5-0.4-0.5-0.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:MarketOffSystemSales100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, bkh:RetailElectricNaturalGasandCoal


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-7.14-7.107-7.623-8.1-7.916-7.839-8.738-8.146-7.041-8.128-8.433-7.941-7.979-7.842
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.9-1.1-1.6-2.4-2.4-1.5-1.8-2.5-2.1-1.4-1.7-2.5-2.3-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.9-1.1-1.6-2.4-2.4-1.5-1.8-2.5-2.1-1.4-1.7-2.5-2.3-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:RetailElectricNaturalGasandCoal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, bkh:TransmissionOther


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-5.299-5.296-5.235-5.235-4.432-4.413-4.189-4.206-4.199-4.203-3.86-3.693-3.644-3.631
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.4-0.8-1.1-1.5-1.4-0.8-0.9-1.3-1.3-0.7-0.8-1.2-1.0-0.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.4-0.8-1.1-1.5-1.4-0.8-0.9-1.3-1.3-0.7-0.8-1.2-1.0-0.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:TransmissionOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, bkh:Transportation


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-0.109-0.11-0.11-0.139-0.138-0.139-0.139-0.195-0.276-0.432-0.371-0.267-0.301-0.409
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:Transportation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, bkh:Wholesale


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-23.48-24.451-24.56-24.521-24.476-23.612-50.654-14.414-13.296-13.213-9.688-13.047-11.613-12.213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-6.4-3.9-5.1-7.1-7.5-4.5-10.6-4.5-4.0-2.2-1.9-4.1-3.3-2.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-6.4-3.9-5.1-7.1-7.5-4.5-10.6-4.5-4.0-2.2-1.9-4.1-3.3-2.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:Wholesale100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ConsolidationItems, us-gaap:TimingOfTransferOfGoodOrService

us-gaap:IntersegmentElimination, us-gaap:TransferredAtPointInTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-7.14-7.107-7.623-8.1-7.916-7.839-8.738-8.146-7.041-8.128-8.433-7.941-7.978-7.842
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.9-1.1-1.6-2.4-2.4-1.5-1.8-2.5-2.1-1.4-1.7-2.5-2.3-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-1.9-1.1-1.6-2.4-2.4-1.5-1.8-2.5-2.1-1.4-1.7-2.5-2.3-1.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination us-gaap:TransferredAtPointInTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-30.563-32.741-32.579-31.799-30.626-30.803-57.671-20.303-19.106-20.072-16.49-18.356-17.219-18.775
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.3-5.2-6.8-9.2-9.4-5.8-12.1-6.3-5.8-3.4-3.3-5.7-4.9-3.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-8.3-5.2-6.8-9.2-9.4-5.8-12.1-6.3-5.8-3.4-3.3-5.7-4.9-3.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MajorCustomers

bkh:ExternalCustomers


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3686304823443245304743233295975023200.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.099.4100.0100.0100.0100.3100.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax100.0100.0100.0100.0100.0100.099.4100.0100.0100.0100.3100.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0

bkh:MarketOffSystemSales


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value7.3534.8453.7587.6671.9812.3664.715.1032.2744.6854.2247.853.442.049
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.00.80.82.20.60.41.01.60.70.80.82.51.00.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.00.80.82.20.60.41.01.60.70.80.82.51.00.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:MarketOffSystemSales100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:RetailElectricNaturalGasandCoal


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value309547410270269453407258268515420254289497
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax83.986.885.278.583.185.585.480.081.586.283.879.582.286.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax83.986.885.278.583.185.585.480.081.586.283.879.582.286.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:RetailElectricNaturalGasandCoal100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:TransmissionOther


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1620222017232221212328182122
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.43.24.66.05.44.34.66.56.63.95.85.76.13.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.43.24.66.05.44.34.66.56.63.95.85.76.13.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:TransmissionOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Transportation


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3147413830434128284439292841
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.67.68.611.19.58.38.68.98.67.47.99.38.17.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.67.68.611.19.58.38.68.98.67.47.99.38.17.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Transportation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Wholesale


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4.442104.3657.4534.7127.407-0.5979.9158.547109.7379.6939.32110
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.60.92.21.51.4-0.13.12.61.81.93.02.61.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.21.60.92.21.51.4-0.13.12.61.81.93.02.61.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Wholesale100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:MajorCustomers, us-gaap:StatementBusinessSegments

bkh:ExternalCustomers, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value177220169194156167162185159176173179166167
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.135.035.156.648.231.634.157.448.329.534.556.147.329.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax48.135.035.156.648.231.634.157.448.329.534.556.147.329.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:ExternalCustomers, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value183398304141159354302129163411320130176395
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.763.263.141.049.366.863.440.049.568.863.940.750.069.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.763.263.141.049.366.863.440.049.568.863.940.750.069.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:ExternalCustomers, bkh:Mining


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value6.7126.9777.0276.5686.936.5647.2466.8465.5387.557.7178.8098.3678.715
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.11.51.92.11.21.52.11.71.31.52.82.41.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.11.51.92.11.21.52.11.71.31.52.82.41.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Mining100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:ExternalCustomers, bkh:PowerGeneration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.4324.2411.4651.5281.2421.8551.8551.7031.7652.2571.5461.4371.131.72
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.70.30.40.40.30.40.50.50.40.30.40.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.70.30.40.40.30.40.50.50.40.30.40.30.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:PowerGeneration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:IntercompanyCustomers, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value5.5626.7716.4485.6775.3766.4136.535.3395.2376.016.2795.0325.2976.1445.5822.333
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.51.11.31.61.71.21.41.61.61.01.31.61.51.11.20.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.51.11.31.61.71.21.41.61.61.01.31.61.51.11.20.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:IntercompanyCustomers, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.5191.521.5711.6010.7740.7780.4880.5490.7230.6990.5220.2750.3090.418-0.0550.073
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.20.30.50.20.10.10.20.20.10.10.10.10.1-0.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.20.30.50.20.10.10.20.20.10.10.10.10.1-0.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:IntercompanyCustomers, bkh:Mining


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value7.1427.1067.6238.17.9167.8398.7388.1466.898.2798.4337.9427.9787.842
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.91.11.62.42.41.51.82.52.11.41.72.52.31.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.91.11.62.42.41.51.82.52.11.41.72.52.31.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:Mining100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:IntercompanyCustomers, bkh:PowerGeneration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value232424242423501413139.689131213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.43.95.17.17.54.510.64.54.02.21.94.13.52.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.43.95.17.17.54.510.64.54.02.21.94.13.52.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:PowerGeneration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:MarketOffSystemSales, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8.9417.6566.3699.5353.5384.8677.2256.4523.4486.6926.6579.0594.9384.144
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.41.21.32.81.10.91.52.01.01.11.32.81.40.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.41.21.32.81.10.91.52.01.01.11.32.81.40.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:MarketOffSystemSales bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:MarketOffSystemSales, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.0870.0730.0630.0360.0230.1380.1740.1390.1610.2170.1380.140.1620.427
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:MarketOffSystemSales bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:RetailElectricNaturalGasandCoal, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value158198150169141148150162139153144157145147
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax43.031.531.349.243.728.031.550.142.425.728.949.141.225.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax43.031.531.349.243.728.031.550.142.425.728.949.141.225.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:RetailElectricNaturalGasandCoal bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:RetailElectricNaturalGasandCoal, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value143341252941202982508912335426788135341
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.054.252.427.437.256.352.427.737.559.253.427.738.559.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.054.252.427.437.256.352.427.737.559.253.427.738.559.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:RetailElectricNaturalGasandCoal bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:RetailElectricNaturalGasandCoal, bkh:Mining


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1314141414141514121516161616
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:RetailElectricNaturalGasandCoal bkh:Mining100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:TransmissionOther, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1215151512141414141419101313
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.32.43.34.53.92.83.04.44.42.43.93.23.82.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.32.43.34.53.92.83.04.44.42.43.93.23.82.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:TransmissionOther bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:TransmissionOther, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value9.1251011109.189121110111313111112
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.51.62.43.02.82.42.53.43.52.22.63.73.32.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax2.51.62.43.02.82.42.53.43.52.22.63.73.32.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:TransmissionOther bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Transportation, bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3147413830444129284439302941
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.67.68.611.19.58.38.69.08.77.48.09.48.27.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.67.68.611.19.58.38.69.08.77.48.09.48.27.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Transportation bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Wholesale, bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value3.015.9222.9015.9253.475.552-2.458.216.7818.3438.198.2558.1919.05
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.80.90.61.71.11.0-0.52.52.11.41.62.62.31.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.80.90.61.71.11.0-0.52.52.11.41.62.62.31.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Wholesale bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Wholesale, bkh:PowerGeneration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2428262625255216151511141213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Wholesale bkh:PowerGeneration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value182227175200161173169191164182179184171173
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.636.136.558.349.832.835.559.049.830.535.857.648.830.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.636.136.558.349.832.835.559.049.830.535.857.648.830.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:GasUtilities


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value184400305142160355303129164412320130176396
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.163.563.441.549.567.063.540.149.768.964.040.850.169.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.163.563.441.549.567.063.540.149.768.964.040.850.169.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Mining


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1314141414141514121516161616
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Mining100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:PowerGeneration


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2428262625255216151511141213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:PowerGeneration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementBusinessSegments, us-gaap:TimingOfTransferOfGoodOrService

bkh:ElectricUtilities, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value182227175200161173169191164182179184171173
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.636.136.558.349.832.835.559.049.830.535.857.648.830.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax49.636.136.558.349.832.835.559.049.830.535.857.648.830.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ElectricUtilities us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:GasUtilities, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value184400305142160355303129164412320130176396
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.163.563.441.549.567.063.540.149.768.964.040.850.169.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.163.563.441.549.567.063.540.149.768.964.040.850.169.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:GasUtilities us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Mining, us-gaap:TransferredAtPointInTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1314141414141514121516161616
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.82.23.04.34.62.73.34.63.82.63.25.24.62.9
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Mining us-gaap:TransferredAtPointInTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:PowerGeneration, us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2428262625255216151511141213
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.84.65.47.67.94.811.05.04.62.62.24.53.62.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:PowerGeneration us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:TimingOfTransferOfGoodOrService

us-gaap:TransferredAtPointInTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value6.7146.9767.0276.5686.936.5647.2466.8465.3877.7017.7178.818.3678.715
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.11.51.92.11.21.52.11.61.31.52.82.41.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.11.51.92.11.21.52.11.61.31.52.82.41.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:TransferredAtPointInTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:TransferredOverTime


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value361623475337317523467316324590494311344564
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax98.298.998.598.197.998.897.997.998.498.798.797.297.698.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax98.298.998.598.197.998.897.997.998.498.798.797.297.698.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:TransferredOverTime100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues

us-gaap:Revenues


Revenues
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value372633486346326537477325333597501321355575455335341547463333325449318272272441378272283460355259279380318246242365361256273400314249256416
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax101.1100.5100.9100.7100.8101.3100.0100.6101.3100.0100.0100.6100.9100.4100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Revenues us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-38.188-40.33-39.993-39.935-38.934-39.033-39.267-37.943-35.688-37.871-34.028-35.391-35.175-36.577-380.261-31.274-29.812-33.519-379.5-31.956-28.408-35.755-258.912-31.751-30.785-31.937-250.844-32.264-32.925-33.966-251.957-31.0-30.299-31.058
Percentage of Revenues-10.2-6.4-8.2-11.5-11.9-7.3-8.2-11.7-10.7-6.3-6.8-11.0-9.9-6.4-83.5-9.3-8.7-6.1-81.8-9.6-8.7-7.9-81.4-11.7-11.3-7.2-66.3-11.9-11.6-7.4-70.9-11.9-10.8-8.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-10.4-6.4-8.3-11.6-12.0-7.4-8.2-11.7-10.8-6.3-6.8-11.1-10.0-6.4-83.5-9.3-8.7-6.1-81.8-9.6-8.7-7.9-81.4-11.7-11.3-7.2-66.3-11.9-11.6-7.4-70.9-11.9-10.8-8.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination101.3101.299.5100.1101.0101.059.1133.4136.5134.3136.5134.6139.6137.40.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:ConsolidationItems, us-gaap:ProductOrService

us-gaap:IntersegmentElimination, bkh:Other


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value-0.485-0.4820.209-0.036-0.392-0.39127-9.494-9.541-9.671-9.105-9.094-9.118-9.124
Percentage of Revenues-0.1-0.10.0-0.0-0.1-0.15.7-2.9-2.9-1.6-1.8-2.8-2.6-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.10.0-0.0-0.1-0.15.7-2.9-2.9-1.6-1.8-2.8-2.6-1.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination bkh:Other0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:MajorCustomers, us-gaap:ProductOrService

bkh:ExternalCustomers, bkh:Other


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4.1493.2154.2972.2782.7216.8412.7231.8034.142-0.16-1.3651.8163.2432.034
Percentage of Revenues1.10.50.90.70.81.30.60.61.2-0.0-0.30.60.90.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.10.50.90.70.81.30.60.61.3-0.0-0.30.60.90.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Other0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:MajorCustomers, us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

bkh:ExternalCustomers, bkh:Other, bkh:ElectricUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2.2790.1370.1270.2241.6270.2232.7260.2341.9770.2540.2090.2311.7540.233
Percentage of Revenues0.60.00.00.10.50.00.60.10.60.00.00.10.50.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.00.00.10.50.00.60.10.60.00.00.10.50.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Other bkh:ElectricUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:ExternalCustomers, bkh:Other, bkh:GasUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.252.4082.8790.8630.5125.708-0.750.811.443-1.119-2.1511.0110.9121.184
Percentage of Revenues0.30.40.60.20.21.1-0.20.20.4-0.2-0.40.30.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.40.60.30.21.1-0.20.30.4-0.2-0.40.30.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Other bkh:GasUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:ExternalCustomers, bkh:Other, bkh:Mining


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.2340.2490.9310.7770.2330.4670.2890.2280.2880.2690.230.2260.2290.246
Percentage of Revenues0.10.00.20.20.10.10.10.10.10.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.00.20.20.10.10.10.10.10.00.00.10.10.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Other bkh:Mining0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:ExternalCustomers, bkh:Other, bkh:PowerGeneration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.3860.4210.360.4140.3490.4430.4580.5310.4340.4360.3470.3480.3480.371
Percentage of Revenues0.10.10.10.10.10.10.10.20.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.10.10.20.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ExternalCustomers bkh:Other bkh:PowerGeneration0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:IntercompanyCustomers, bkh:Other, bkh:GasUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.0940.0920.0980.190.00.00.00.00.00.00.00.00.00.0
Percentage of Revenues0.00.00.00.10.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.10.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:Other bkh:GasUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:IntercompanyCustomers, bkh:Other, bkh:Mining


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.3410.34-0.363-0.2090.3370.3350.330.3320.3290.3310.3250.3240.3250.325
Percentage of Revenues0.10.1-0.1-0.10.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.1-0.1-0.10.10.10.10.10.10.10.10.10.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:Other bkh:Mining0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:IntercompanyCustomers, bkh:Other, bkh:PowerGeneration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.050.050.0560.0550.0550.056-27.4729.1629.2129.348.788.778.7938.799
Percentage of Revenues0.00.00.00.00.00.0-5.82.82.81.61.82.72.51.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.0-5.82.82.81.61.82.72.51.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:IntercompanyCustomers bkh:Other bkh:PowerGeneration0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:ProductOrService

bkh:Other


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value4.1493.2154.2972.2782.7216.8412.7231.8034.142-0.16-1.3651.8163.2432.034
Percentage of Revenues1.10.50.90.70.81.30.60.61.2-0.0-0.30.60.90.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.10.50.90.70.81.30.60.61.3-0.0-0.30.60.90.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Other0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

bkh:Other, bkh:ElectricUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2.2790.1370.1270.2241.6270.2232.7260.2341.9770.2540.2090.2311.7540.233
Percentage of Revenues0.60.00.00.10.50.00.60.10.60.00.00.10.50.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.60.00.00.10.50.00.60.10.60.00.00.10.50.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Other bkh:ElectricUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:Other, bkh:GasUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.3442.52.9761.0530.5125.708-0.7510.8111.443-1.119-2.1511.0110.9121.184
Percentage of Revenues0.40.40.60.30.21.1-0.20.20.4-0.2-0.40.30.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.40.40.60.30.21.1-0.20.30.4-0.2-0.40.30.30.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Other bkh:GasUtilities0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:Other, bkh:Mining


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.5750.5890.5680.5680.570.8020.6190.560.6170.60.5550.550.5540.571
Percentage of Revenues0.20.10.10.20.20.10.10.20.20.10.10.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.20.10.10.20.20.20.10.20.20.10.10.20.20.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Other bkh:Mining0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:Other, bkh:PowerGeneration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.4360.4710.4170.4690.4040.499-27.0139.6929.6469.7769.1279.1189.1419.17
Percentage of Revenues0.10.10.10.10.10.1-5.73.02.91.61.82.82.61.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.10.10.10.1-5.73.02.91.61.82.82.61.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Other bkh:PowerGeneration0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value184227175200163174172191166182179184173173171181165172170171158163177182169182174171158178169169154158
Percentage of Revenues49.635.936.257.949.932.436.058.849.830.635.857.448.830.237.654.048.431.436.851.548.736.355.767.062.441.446.363.056.038.747.665.255.241.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.236.136.558.350.332.836.059.150.430.635.857.749.330.337.654.048.431.436.851.548.736.355.767.062.441.446.363.056.038.747.665.255.241.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:ElectricUtilities101.2100.1100.1100.1101.0100.1101.6100.1101.2100.1100.1100.1101.0100.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:GasUtilities


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value18640230814316136030213016541131813117739727314216636427414115326812168792371777810225916667105199
Percentage of Revenues49.963.563.541.549.367.263.440.249.668.863.640.949.969.160.142.648.766.659.242.447.259.738.125.329.253.846.928.936.256.446.826.137.852.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax50.563.964.141.849.768.063.440.450.268.763.641.150.469.360.142.648.766.659.242.447.259.738.125.329.253.846.928.936.256.446.826.137.852.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:GasUtilities100.7100.6101.0100.7100.3101.699.8100.6100.999.799.3100.8100.5100.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

bkh:Mining


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value14141515151516151316161716178.9639.7428.4038.3558.5699.0423.9227.5348.2298.899.0528.142
Percentage of Revenues3.92.33.14.44.72.83.54.83.92.73.35.44.83.02.02.92.51.51.82.71.21.72.63.33.31.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax3.92.33.24.44.82.93.54.84.02.73.35.44.83.02.02.92.51.51.82.71.21.72.63.33.31.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:Mining104.2104.2103.9103.9103.8105.6103.9103.7105.0103.8103.4103.3103.4103.40.00.00.00.00.00.00.00.00.00.00.00.0

bkh:PowerGeneration


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2529262626252525242520232223
Percentage of Revenues6.84.65.47.78.04.85.37.97.44.24.17.36.44.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.94.65.57.78.14.95.38.07.54.24.17.46.54.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax bkh:PowerGeneration101.8101.6101.6101.8101.6102.048.6160.1164.0163.2181.2162.9178.5171.8

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value87388696808878297689764875587274708170376963666165706626665865516489647565156452639463244655424642204319427940733970396438753801374636863729385337743807412739533810372737113540337033583317
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value93941101081671801301742162072091771781941151141081091101411521185841301381051061051008980130146112115
Percentage of Assets1.11.11.41.42.22.41.72.43.12.93.02.72.72.91.71.71.71.71.72.22.41.912.63.13.32.42.52.62.52.32.13.43.93.13.1
Percentage of Assets1.11.11.41.42.22.41.72.43.12.93.02.72.72.91.71.71.71.71.72.22.41.912.63.13.32.42.52.62.52.32.13.43.93.13.1
Percentage of Assets us-gaap:CorporateNonSegment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value323932173120304029822931290028102777275528952853290228902906291129012872285928242777271428592846285628172748267126032572252524642417236723872302230022682254191719001868183417711736
Percentage of Assets37.137.038.638.838.838.338.438.639.239.141.642.844.243.643.644.444.744.443.943.843.442.961.467.067.765.264.265.665.664.965.264.864.564.264.059.861.059.654.648.549.950.149.450.051.5
Percentage of Assets37.137.038.638.838.838.338.438.639.239.141.642.844.243.643.644.444.744.443.943.843.442.961.467.067.765.264.265.665.664.965.264.864.564.264.059.861.059.654.648.549.950.149.450.051.5
Percentage of Assets bkh:ElectricUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:GasUtilities


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value4935490043764201405240434032379736453639362334333367339834263288324232603307318231423146864831801839906827799842805757734752765710684717746683659683722659622
Percentage of Assets56.556.454.153.752.752.953.352.251.551.752.051.551.351.351.550.250.050.450.849.349.149.718.619.619.019.421.220.320.121.320.819.919.620.420.518.418.118.818.117.317.318.419.518.618.5
Percentage of Assets56.556.454.153.752.752.953.352.251.551.752.051.551.351.351.550.250.050.450.849.349.149.718.619.619.019.421.220.320.121.320.819.919.620.420.518.418.118.818.117.317.318.419.518.618.5
Percentage of Assets bkh:GasUtilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:Mining


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value7576777579807778626380726865656667646766717376787677
Percentage of Assets0.90.91.01.01.01.01.01.10.90.91.21.11.01.01.01.01.01.01.01.01.11.21.61.81.81.8
Percentage of Assets0.90.91.01.01.01.01.01.10.90.91.21.11.01.01.01.01.01.01.01.01.11.21.61.81.81.8
Percentage of Assets bkh:Mining100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:PowerGeneration


Assetsus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value39440640440340741241741437937215412249536064667273778074607872757664859095102108115119119122128129372353336293249197
Percentage of Assets4.54.75.05.25.35.45.55.75.45.32.21.80.80.80.91.01.01.11.11.21.31.21.31.91.71.81.81.62.12.32.52.72.93.13.23.13.33.43.19.49.39.07.97.15.9
Percentage of Assets4.54.75.05.25.35.45.55.75.45.32.21.80.80.80.91.01.01.11.11.21.31.21.31.91.71.81.81.62.12.32.52.72.93.13.23.13.33.43.19.49.39.07.97.15.9
Percentage of Assets bkh:PowerGeneration100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value87388696808878297689764875587274708170376963666165706626665865516489647565156452639463244655424642204319427940733970396438753801374636863729385337743807412739533810372737113540337033583317
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value26592624256125192513252323622329231622792181181318181818170816821676167416141604156214801465128713101376130712321214119612241209108811081113110010801082110710841050969
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.430.231.732.232.733.031.332.032.732.431.327.227.727.425.725.725.825.924.824.924.423.431.530.331.132.233.733.031.531.732.229.327.529.129.929.630.532.133.032.70.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value571578493403414489473377369484503384380492570385359401466418443423822402438438454373344404345328338343405570336407758666616611670644553625624
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.56.76.15.25.46.46.35.25.26.97.25.85.87.48.65.95.56.27.26.56.96.717.79.510.410.210.69.28.710.28.98.79.09.310.914.88.910.718.416.816.216.418.118.216.418.618.8

us-gaap:AssetsCurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Assets
Period End2020-12-312019-12-312018-12-31
Value131313
Percentage of AssetsCurrent2.82.82.7
Percentage of Assets0.20.20.2
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.00.00.0

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value1.175136.3566.95531549.777136.6421220108.633015131111136211646456388763211114177.8411330121524740562174884432586413611216881
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.20.10.10.40.70.10.20.10.20.30.20.10.50.20.20.20.20.21.01.80.79.80.92.11.50.50.30.40.40.20.40.80.30.46.41.11.50.51.92.31.20.91.71.94.03.40.00.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value5.734171011355813161015241311331816141315
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.10.10.50.80.20.20.10.20.30.20.20.50.30.20.20.20.2

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value189282265160170238255148166282269152175257248153169224263154150206147115123178189123135203177114132168163104109143156241244306328234208242274
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.23.23.32.02.23.13.42.02.44.03.92.32.73.93.72.32.63.54.02.42.33.33.22.72.94.14.43.03.45.14.63.03.54.64.42.72.93.83.86.16.48.28.96.66.27.28.3

us-gaap:AccountsReceivableNetCurrent us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Accounts
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value1.1181.1026.0923.0643.7774.8392.031.4751.9161.4570.6291.1671.12.2281.6592.6272.4211.0261.5660.9830.9812.5551.4592.0122.6970.6042.2261.9351.0260.799
Percentage of AccountsReceivableNetCurrent0.40.44.11.81.31.81.30.80.70.60.40.70.50.81.11.71.20.71.40.80.51.31.21.51.30.32.01.50.60.5
Percentage of Assets0.00.00.10.00.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.00.10.10.00.10.10.00.0
Percentage of Assets us-gaap:CorporateNonSegment1.00.83.51.41.82.31.10.81.01.30.61.11.02.01.21.72.00.21.20.70.92.41.42.03.00.71.71.30.90.7

us-gaap:AccountsReceivableNetCurrent us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Accounts
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value77747071767474797375717469777574738377797785746973756868687764616363575361695853
Percentage of AccountsReceivableNetCurrent29.129.247.342.727.027.648.545.028.630.346.844.031.129.648.649.635.856.767.364.043.545.060.451.435.942.660.251.940.847.561.956.343.940.423.922.020.121.225.225.7
Percentage of Assets1.01.01.01.01.11.11.11.21.11.11.11.21.11.21.21.21.21.81.81.91.82.01.81.71.82.01.81.81.92.11.71.61.71.51.51.41.71.91.71.6
Percentage of Assets bkh:ElectricUtilities2.52.62.52.62.82.62.62.72.62.62.52.62.42.72.72.72.72.92.72.82.83.12.82.72.83.02.82.82.93.32.82.72.82.83.02.83.33.83.33.1

bkh:GasUtilities


Accounts
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value183175678719618471901771677386146174696712355273390923551112893250867127306177324478802937
Percentage of AccountsReceivableNetCurrent68.868.645.652.369.668.446.651.468.867.547.651.265.166.345.145.160.137.524.127.350.748.529.138.055.550.628.138.351.443.526.328.243.049.313.618.025.724.612.718.1
Percentage of Assets2.32.30.91.22.82.61.11.42.72.51.11.32.32.71.11.12.01.20.70.82.12.20.91.32.82.30.81.42.41.90.70.81.61.90.81.22.12.20.81.1
Percentage of Assets bkh:GasUtilities4.24.41.82.45.45.12.12.75.24.92.22.74.55.32.22.23.96.43.44.210.810.24.36.413.411.14.26.911.59.33.94.58.610.44.86.711.511.24.56.0

bkh:Mining


Accounts
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value2.5112.2771.8042.5052.7913.9883.7493.1583.1332.8043.5342.9043.1973.3523.6121.1142.4842.762.6843.4023.638
Percentage of AccountsReceivableNetCurrent0.90.91.21.51.01.52.51.81.21.12.31.71.41.32.30.71.21.92.32.82.0
Percentage of Assets0.00.00.00.00.00.10.10.00.00.00.10.00.00.10.10.00.00.10.10.10.1
Percentage of Assets bkh:Mining3.33.02.34.04.44.95.24.64.84.35.34.34.95.05.41.63.43.63.44.54.7

bkh:PowerGeneration


Accounts
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1.8372.1642.7332.8673.1671.8761.6961.6811.581.1961.010.8771.3531.421.1651.2291.211.1871.1861.1991.1521.3691.3681.3881.341.7220.0030.1570.0030.0160.0040.1970.2650.2820.1190.1062.050.3070.4630.346
Percentage of AccountsReceivableNetCurrent0.70.81.81.71.10.71.11.00.60.50.70.50.60.50.80.80.60.81.01.00.60.71.11.00.71.00.00.10.00.00.00.20.20.20.00.00.70.10.20.2
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.00.00.0
Percentage of Assets bkh:PowerGeneration0.50.50.70.80.91.21.43.43.02.01.61.31.91.91.51.51.62.01.51.71.51.82.11.61.51.80.00.10.00.00.00.20.20.20.00.00.60.10.20.2

Inventory Net

us-gaap:InventoryNet

us-gaap:InventoryNet


Inventory
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value1141021171261059211712310287117122958211312699841071138578869073669110581668895736477806163841341056913914513591123
Percentage of InventoryNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.31.21.51.61.41.21.61.71.51.21.71.81.51.21.71.91.51.31.61.81.31.21.92.11.71.52.12.62.01.72.32.52.01.72.12.11.61.72.03.42.81.93.84.14.02.73.7

Inventory Raw Materials And Supplies

us-gaap:InventoryRawMaterialsAndSupplies

us-gaap:InventoryRawMaterialsAndSupplies


Inventory
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value858885939288828180767573737269737271686767665553545249525150505051504343414440373634313132
Percentage of InventoryRawMaterialsAndSupplies100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.01.01.11.21.21.21.11.11.11.11.11.11.11.11.01.11.11.11.11.01.11.11.21.31.31.21.21.31.31.31.31.31.41.41.21.11.11.21.01.01.00.90.90.91.0

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value2225263327262629272829323124252621232730303471555147242621242527272828442626216556602520132627
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.30.30.30.40.40.30.40.40.40.40.40.50.50.40.40.40.30.40.40.50.50.51.51.31.21.10.60.70.50.60.70.70.70.80.81.20.70.70.51.71.51.60.70.60.40.80.8

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value75587415730571286954680867846567631761276000581957025608556766156533643664126306620960634976488247264652456344934408431842594152406639773930395038633800372436643559346133593243314130452975
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets86.585.390.391.190.489.089.890.389.287.186.287.386.884.683.6101.0100.799.498.497.797.195.9106.9115.0112.0107.7106.6110.3111.0108.9109.9109.2108.5107.9105.4102.5102.499.890.292.793.492.990.591.693.290.789.7

us-gaap:PropertyPlantAndEquipmentGross us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value22292211171510114.243
Percentage of PropertyPlantAndEquipmentGross0.30.40.40.20.30.30.20.30.1
Percentage of Assets0.30.40.30.20.30.30.30.30.1
Percentage of Assets us-gaap:CorporateNonSegment20.022.310.610.315.72.710.113.83.7

us-gaap:PropertyPlantAndEquipmentGross us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value32483059310929902875276925972464227621491720
Percentage of PropertyPlantAndEquipmentGross44.545.151.853.744.855.656.957.957.957.751.2
Percentage of Assets40.240.544.744.944.159.560.763.661.152.146.4
Percentage of Assets bkh:ElectricUtilities104.1105.5107.4102.9100.696.894.597.695.495.393.8

bkh:GasUtilities


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value33122981250622512099741687627568523502
Percentage of PropertyPlantAndEquipmentGross45.343.941.840.432.714.915.114.714.514.115.0
Percentage of Assets41.039.436.033.832.215.916.116.215.212.713.5
Percentage of Assets bkh:GasUtilities75.773.969.265.763.585.775.877.974.370.169.6

bkh:Mining


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value187180175158156158
Percentage of PropertyPlantAndEquipmentGross2.62.72.92.82.43.2
Percentage of Assets2.32.42.52.42.43.4
Percentage of Assets bkh:Mining243.3233.8217.9242.0232.2207.3

bkh:PowerGeneration


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value534534185155162158156153140135297
Percentage of PropertyPlantAndEquipmentGross7.37.93.12.82.53.23.43.63.63.78.9
Percentage of Assets6.67.12.72.32.53.43.64.03.83.38.0
Percentage of Assets bkh:PowerGeneration132.3128.0120.5256.0221.6261.1202.8160.4118.1105.3101.6

Construction In Progress Gross

us-gaap:ConstructionInProgressGross us-gaap:ConsolidationItems

us-gaap:ConstructionInProgressGross

us-gaap:CorporateNonSegment


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value1623166.37411155.1965.6473.875
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.30.20.10.20.30.10.10.1
Percentage of Assets us-gaap:CorporateNonSegment14.917.97.95.510.82.64.97.03.4

us-gaap:ConstructionInProgressGross us-gaap:StatementBusinessSegments

bkh:Mining


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value0.9881.2750.00.04.6423.649
Percentage of ConstructionInProgressGross6.05.50.00.038.823.7
Percentage of Assets0.00.00.00.00.10.1
Percentage of Assets bkh:Mining1.31.70.00.06.94.8

bkh:PowerGeneration


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value4.8762.121110.2241.2982.1822.262101.3230.93163
Percentage of ConstructionInProgressGross29.79.171.33.510.814.243.5185.834.10.00.0
Percentage of Assets0.10.00.20.00.00.00.10.30.00.04.4
Percentage of Assets bkh:PowerGeneration1.20.57.60.41.83.62.911.01.10.755.7

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value1361132012851276125112231281124312241187114511181087104810262020198119431943184118191742171716171522135113241338132512981269125812341210118812531006980934934916889864880852830815
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets15.615.215.916.316.316.017.017.117.316.916.416.816.615.815.430.830.530.029.828.528.527.536.938.136.131.330.932.933.432.732.833.133.032.831.932.526.725.822.623.624.023.923.324.925.324.724.6

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312013-12-312012-12-31
Value1.1440.9640.670.3092.106-3.21-1.956
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment0.10.10.10.00.1-0.3-0.2
Percentage of Assets0.00.00.00.00.0-0.1-0.1
Percentage of Assets us-gaap:CorporateNonSegment1.00.70.30.31.9-4.0-1.7

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value666670706644578540484472439385357
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment51.852.361.762.829.831.536.637.337.041.341.4
Percentage of Assets8.28.910.29.78.911.611.312.211.89.39.6
Percentage of Assets bkh:ElectricUtilities21.423.124.422.220.218.917.618.718.417.119.5

bkh:GasUtilities


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value3233362792291941069284685247
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment25.226.324.422.310.06.27.06.75.85.65.5
Percentage of Assets4.04.54.03.43.02.32.22.21.81.31.3
Percentage of Assets bkh:GasUtilities7.48.47.76.75.912.310.110.59.07.06.5

bkh:Mining


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value12611811110810597
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment9.89.39.810.65.45.7
Percentage of Assets1.61.61.61.61.62.1
Percentage of Assets bkh:Mining164.2153.7138.6166.3156.2127.9

bkh:PowerGeneration


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value167154645755514743383530
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment13.012.05.65.62.83.03.63.43.23.83.6
Percentage of Assets2.12.00.90.90.81.11.11.11.00.80.8
Percentage of Assets bkh:PowerGeneration41.537.041.795.075.184.662.045.032.327.210.6

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value61966095601958515703558455035323509249394854470046144559454145944551449344684465438943213259326432033300323931553082301929902893283127662742269628562819278927302643257224952362228822142160
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets70.970.174.474.774.273.072.873.271.970.269.770.670.268.868.270.170.169.468.669.268.668.370.076.975.976.475.777.577.676.277.276.175.675.173.570.075.774.067.669.169.469.067.266.767.965.965.1

us-gaap:PropertyPlantAndEquipmentNet us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Property
Period End2020-12-312019-12-312018-12-31
Value190193199
Percentage of PropertyPlantAndEquipmentNet3.23.54.1
Percentage of Assets2.42.62.9
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.00.00.0

us-gaap:PropertyPlantAndEquipmentNet us-gaap:ConsolidationItems

us-gaap:CorporateNonSegment


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value20283925232014146.199
Percentage of PropertyPlantAndEquipmentNet0.30.50.80.60.50.60.40.50.2
Percentage of Assets0.30.40.60.40.40.40.30.40.2
Percentage of Assets us-gaap:CorporateNonSegment19.021.618.922.221.33.513.317.85.4

us-gaap:PropertyPlantAndEquipmentNet us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value25812388240223462297222821121991183717631363
Percentage of PropertyPlantAndEquipmentNet42.943.449.551.751.468.465.266.667.063.254.6
Percentage of Assets31.931.634.535.235.347.949.451.449.342.736.7
Percentage of Assets bkh:ElectricUtilities82.782.383.080.780.377.976.978.876.978.274.3

bkh:GasUtilities


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value29882644222620221904634595542499471455
Percentage of PropertyPlantAndEquipmentNet49.748.145.944.542.619.518.418.218.216.918.2
Percentage of Assets37.035.032.030.429.213.613.914.013.411.412.3
Percentage of Assets bkh:GasUtilities68.365.661.559.057.673.465.767.465.363.163.0

bkh:Mining


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value616163495160
Percentage of PropertyPlantAndEquipmentNet1.01.11.31.11.11.9
Percentage of Assets0.80.80.90.70.81.3
Percentage of Assets bkh:Mining79.180.279.475.775.979.4

bkh:PowerGeneration


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value36738012197107107108110102100266
Percentage of PropertyPlantAndEquipmentNet6.16.92.52.22.43.33.33.73.73.610.7
Percentage of Assets4.55.01.71.51.72.32.52.92.72.47.2
Percentage of Assets bkh:PowerGeneration90.891.078.8161.0146.5176.5140.8115.485.778.191.0

Long Term Investments

us-gaap:LongTermInvestments

us-gaap:LongTermInvestments


Long
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value151515152121414141414140131212121212121211121217171717161616161616161616171717171717181818
Percentage of LongTermInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.30.30.60.60.60.60.60.60.20.20.20.20.20.20.20.20.30.30.30.40.40.40.40.40.40.40.40.40.40.40.40.40.40.40.50.50.50.50.50.50.6

us-gaap:LongTermInvestments us-gaap:FairValueByAssetClass

us-gaap:CashSurrenderValue


Long
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1313131313121213131213121212
Percentage of LongTermInvestments86.286.086.986.859.559.831.231.731.631.3100.0100.0100.0100.0
Percentage of Assets0.20.20.20.20.20.20.20.20.20.20.20.20.20.2
Percentage of Assets us-gaap:CashSurrenderValue0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:EquitySecurities


Long
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value1.51.51.51.58.35928
Percentage of LongTermInvestments9.59.69.79.838.168.5
Percentage of Assets0.00.00.00.00.10.4
Percentage of Assets us-gaap:EquitySecurities0.00.00.00.00.00.0

us-gaap:Investments


Long
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302018-12-31
Value0.6820.6920.5150.5150.5140.3170.101
Percentage of LongTermInvestments4.34.43.33.42.31.50.2
Percentage of Assets0.00.00.00.00.00.00.0
Percentage of Assets us-gaap:Investments0.00.00.00.00.00.00.0

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312016-02-122015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value1299129912991299129912991299129912991299129912991299129912991299129912991299130013031306943359359353353353353353353353353353353353353353353353354354354354353353353353
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets14.914.916.116.616.917.017.217.918.418.518.719.519.819.619.519.820.020.119.920.220.420.70.07.78.58.48.28.38.78.98.99.19.39.49.69.59.29.49.38.69.09.39.59.610.010.510.510.7

us-gaap:Goodwill us-gaap:StatementBusinessSegments

bkh:ElectricUtilities


Goodwillus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value248248248248248256250250256256250250250250250249
Percentage of Goodwill19.119.119.119.119.119.819.219.271.471.470.970.970.970.970.670.6
Percentage of Assets3.13.33.63.73.84.03.94.05.56.05.96.56.76.16.77.5
Percentage of Assets bkh:ElectricUtilities8.08.68.68.58.79.19.09.29.09.09.19.910.511.113.70.0

bkh:GasUtilities


Goodwillus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-312012-12-312011-12-312010-12-312009-12-31
Value104210421042104210421034104410461009694949493
Percentage of Goodwill80.280.280.280.280.279.680.180.227.927.226.626.626.526.5
Percentage of Assets12.913.815.015.716.016.016.316.62.22.22.52.32.52.8
Percentage of Assets bkh:GasUtilities23.825.828.830.431.532.533.233.311.610.612.312.613.00.0

Intangible Assets Net Excluding Goodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill

us-gaap:IntangibleAssetsNetExcludingGoodwill


Intangible
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-31
Value11111112121313131314146.9547.1557.3577.5597.7657.9728.1828.3928.9449.164103.383.443.2113.1213.1763.2313.2863.3423.3973.4533.5083.5653.623.6753.7313.7873.8433.8993.9554.0114.0694.1294.1894.2484.3094.884
Percentage of IntangibleAssetsNetExcludingGoodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.20.20.20.20.20.20.20.20.10.10.10.10.10.10.10.10.10.10.20.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value4188000.04629000.04864000.05161000.05331000.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.1

us-gaap:OperatingLeaseRightOfUseAsset us-gaap:BalanceSheetLocation

us-gaap:OtherNoncurrentAssets


Operating
Period End2020-12-312019-12-31
Value4188000.04629000.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0
Percentage of Assets0.10.1
Percentage of Assets us-gaap:OtherNoncurrentAssets0.00.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value4038372424241925302514171714101113111212151120222828292931282722222119191921192020202020211816
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.50.40.50.30.30.30.30.30.40.40.20.30.30.20.20.20.20.20.20.20.20.20.40.50.70.70.70.70.80.70.70.60.60.60.50.50.50.60.50.50.50.60.60.60.60.50.5

Accounts Payable Current

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value133160183152118136193145150178210115104106160959910515314117012110591788812410010014913077888284695959104219218217279201206194229
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.82.31.91.51.82.62.02.12.53.01.71.61.62.41.51.51.62.42.22.71.92.32.21.82.12.92.52.53.83.42.02.42.22.31.81.61.62.55.55.75.87.55.76.15.86.9

Accrued Liabilities Current

us-gaap:AccruedLiabilitiesCurrent

us-gaap:AccruedLiabilitiesCurrent


Accrued
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value219230243244201203226217188196215201190194219213201203244228218272232229160166170163141145151152135140154179158151151168140141170166130140151
Percentage of AccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.52.63.03.12.62.73.03.02.72.83.13.02.92.93.33.33.13.13.73.53.44.35.05.43.83.94.04.03.63.73.94.03.63.84.14.74.24.03.74.33.73.84.64.73.94.24.6

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value123012296965133847198116914885916487307307886495544383915274801467660422448358379651727653399378704669681734898773556878889852756787639693671644
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets14.114.18.66.65.09.410.79.56.98.49.311.011.111.99.78.56.86.08.17.523.010.49.110.68.58.815.217.816.510.19.818.517.918.519.723.320.514.621.322.522.420.321.218.120.620.019.4

us-gaap:LiabilitiesCurrent us-gaap:ConsolidatedEntities

us-gaap:VariableInterestEntityPrimaryBeneficiary


Liabilities
Period End2020-12-312019-12-312018-12-31
Value5.3186.0135.174
Percentage of LiabilitiesCurrent0.80.70.8
Percentage of Assets0.10.10.1
Percentage of Assets us-gaap:VariableInterestEntityPrimaryBeneficiary0.00.00.0

Long Term Debt Current

us-gaap:LongTermDebtCurrent

us-gaap:LongTermDebtCurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value7.07.08.4369.8714.3075.7435.7435.7435.7435.7435.7432552552555.7435.7435.7435.7435.7435.7439300.00.00.00.00.02752752750.00.02552551041033282278.9772.4732.8933.6134.2545.1815.3144.5392435
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.10.10.10.10.10.10.10.10.10.10.13.83.93.90.10.10.10.10.10.114.60.00.00.00.00.06.46.86.90.00.06.76.82.82.88.56.00.20.10.10.10.10.10.20.10.71.1

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent us-gaap:BalanceSheetLocation

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:AccruedLiabilities


Operating
Period End2020-12-312019-12-31
Value736000.01179000.0
Percentage of OperatingLeaseLiabilityCurrent100.0100.0
Percentage of Assets0.00.0
Percentage of Assets us-gaap:AccruedLiabilities0.00.0

Other Accrued Liabilities Current

us-gaap:OtherAccruedLiabilitiesCurrent

us-gaap:OtherAccruedLiabilitiesCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value312734322825303028283231343745414443493432113849333950
Percentage of OtherAccruedLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.30.40.40.40.30.40.40.40.40.50.50.50.60.70.60.70.70.80.50.50.20.81.20.80.91.2

Long Term Debt

us-gaap:LongTermDebt us-gaap:FairValueByMeasurementBasis

us-gaap:LongTermDebt

us-gaap:CarryingReportedAmountFairValueDisclosure


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value3537353635363536353731423145305430552956295632073113311431153115316632163216321731523159186615671567154215421382139613961396121112141041104212711272
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets40.540.743.745.246.041.141.642.043.142.042.548.147.447.046.847.648.849.749.449.949.349.940.136.937.135.736.033.935.235.236.031.932.428.228.033.033.7
Percentage of Assets us-gaap:CarryingReportedAmountFairValueDisclosure0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value3530352935283526353231363140304930492950295029512858285831093109316032103211321122213159186615671567154212671107112113961396955958936938942104412721280128211831184118611889909931015
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets40.440.643.645.045.941.041.541.943.141.942.444.343.543.146.747.548.749.649.349.834.749.940.136.937.135.729.627.228.335.236.025.125.625.425.224.527.733.431.032.431.131.832.033.629.429.630.6

Deferred Finance Costs Noncurrent Net

us-gaap:DeferredFinanceCostsNoncurrentNet

us-gaap:DeferredFinanceCostsNoncurrentNet


Deferred
Period End2020-12-312017-12-312016-12-312015-12-31
Value24182111
Percentage of DeferredFinanceCostsNoncurrentNet100.0100.0100.0100.0
Percentage of Assets0.30.30.30.2

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value436428408398388387360311
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets5.04.95.15.15.15.14.84.5

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value151150150144142152154134146145145151162160159149176174173171173181146158165162158108116113111169177172167167162157177124131128124122148144140
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.71.71.91.81.92.02.01.82.12.12.12.32.52.42.42.32.72.72.72.72.72.93.13.73.93.83.72.72.92.92.94.54.74.74.54.44.34.14.33.13.43.43.43.54.44.34.2

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5752495655
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent38.033.833.835.331.8
Percentage of Assets0.70.70.70.80.8
Percentage of Assets us-gaap:OtherPostretirementBenefitPlansDefinedBenefit0.00.00.00.00.0

us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312018-12-312017-12-312016-12-31
Value4051504651545875
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent26.835.435.130.133.137.636.643.5
Percentage of Assets0.50.70.70.60.70.80.91.2
Percentage of Assets us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.00.00.00.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value5351414342
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent35.333.228.627.424.3
Percentage of Assets0.70.70.60.70.6
Percentage of Assets us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit0.00.00.00.00.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value133135134120119122124120118118109105104105105137135135138141122124155136154154154144137129133133129125125129124123123128124134129125115114114
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.61.71.51.61.61.61.71.71.71.61.61.61.61.62.12.12.12.12.21.92.03.33.23.73.63.63.53.53.33.43.53.53.43.43.43.33.33.03.23.33.63.53.63.43.43.5

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent us-gaap:BalanceSheetLocation

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OtherNoncurrentLiabilities


Operating
Period End2020-12-312019-12-31
Value3807000.03821000.0
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0
Percentage of Assets0.00.1
Percentage of Assets us-gaap:OtherNoncurrentLiabilities0.00.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value804000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value779000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value776000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value529000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value1643000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-31
Value5438000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0
Percentage of Assets0.1

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-31
Value895000.0
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0
Percentage of Assets0.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302014-12-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-312008-12-312007-12-31
Value26592624256125192513252323622329231622792181181318181818170816821676167416141604156214801465128713101376130712321214119612241209108811081113110010801082110710841050969
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.430.231.732.232.733.031.332.032.732.431.327.227.727.425.725.725.825.924.824.924.423.431.530.331.132.233.733.031.531.732.229.327.529.129.929.630.532.133.032.70.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value27582725266226202614262424642432241923832287192119261927182017951790178817301722167914801465128713101407137613571341133713071290128212601232121411961224
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets31.631.332.933.534.034.332.633.434.233.932.828.829.329.127.327.427.627.626.626.726.323.431.530.331.132.632.233.333.833.733.734.034.234.233.031.531.732.2

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustment


Stockholders
Period End2020-12-312020-03-312019-12-312019-09-302019-06-302019-03-31
Value-0.207-0.2073.390.003-0.0033.39
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-0.0-0.00.10.0-0.00.1
Percentage of Assets-0.0-0.00.00.0-0.00.0
Percentage of Assets srt:CumulativeEffectPeriodOfAdoptionAdjustment0.00.00.00.00.00.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value-24.446-26.328-27.346-26.922-28.434-29.382-30.655-25.695-26.227-26.459-26.916-37.703-38.763-39.924-41.202-34.883-9.055-15.044-17.422
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-0.9-1.0-1.0-1.0-1.1-1.1-1.2-1.1-1.1-1.1-1.2-2.0-2.0-2.1-2.3-2.0-0.6-1.1-1.3
Percentage of Assets-0.3-0.3-0.3-0.3-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.6-0.6-0.6-0.6-0.5-0.2-0.4-0.4
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value1701165816571655165416521552155315221469145011571154115111501138953748742
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest61.760.962.263.263.363.063.063.862.961.663.460.259.959.763.265.865.054.456.8
Percentage of Assets19.519.120.521.221.521.620.521.321.520.920.817.417.617.417.317.520.517.519.2
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value63626262626261616160605353535353514444
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest2.32.32.42.42.42.42.52.52.52.52.62.82.82.82.93.13.53.23.4
Percentage of Assets0.70.70.80.80.80.80.80.80.90.90.90.80.80.80.80.81.11.01.1
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302015-12-312014-12-312013-12-31
Value991001011011011011011031031041051071071091111131131141151170.00.00.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest3.63.73.83.93.93.94.14.34.34.44.65.65.65.76.16.36.46.46.76.80.00.00.0
Percentage of Assets1.11.21.31.31.31.31.31.41.51.51.51.61.61.61.71.71.81.81.81.80.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value921931870828826838778742761777700644652656548457472577515
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest33.434.232.731.631.632.031.630.531.532.630.633.533.934.030.126.532.242.039.5
Percentage of Assets10.510.710.810.610.711.010.310.210.711.010.19.79.99.98.27.010.213.513.3
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-312014-12-312013-12-31
Value-2.988-2.564-2.119-1.71-1.879-1.925-0.267-1.636-1.544-1.432-2.51-4.072-3.642-3.049-2.306-0.791-1.888-1.875-1.968
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-0.1-0.1-0.1-0.1-0.1-0.1-0.0-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.1-0.0-0.1-0.1-0.2
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.1-0.0-0.0-0.0-0.0-0.0-0.1
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value6362626262626161616060535353535353535353525151444444444444444444444444444444433939393939393938
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.70.80.80.80.80.80.80.90.90.90.80.80.80.80.80.80.80.80.80.80.81.11.11.11.01.01.11.11.11.11.21.21.21.21.11.21.21.11.01.01.11.11.11.21.21.2

Additional Paid In Capital

us-gaap:AdditionalPaidInCapital

us-gaap:AdditionalPaidInCapital


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value170116581657165516541652155215531522146914501157115411511150114711451143113811231072960953753751749748746744742742733731727725722604602601598597595593591
Percentage of AdditionalPaidInCapital100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets19.519.120.521.221.521.620.521.321.520.920.817.417.617.417.317.517.717.717.517.416.815.220.517.817.817.417.518.318.818.719.219.719.019.319.117.515.315.816.116.116.917.717.717.8

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value921931870828826838778742761777700644652656548516512513457462469490472504532629599582573570540539532519492478460490476467491498486466468491473
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.510.710.810.610.711.010.310.210.711.010.19.79.99.98.27.97.97.97.07.27.37.810.211.912.614.614.014.314.414.413.914.214.214.113.212.412.212.911.511.812.913.413.113.213.914.614.3

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value-24.446-26.328-27.346-26.922-28.434-29.382-30.655-25.695-26.227-26.459-26.916-37.703-38.763-39.924-41.202-32.566-32.941-33.73-34.883-32.951-31.764-20.825-9.055-14.611-16.859-14.054-15.044-14.839-19.441-18.589-17.422-31.021-30.781-36.224-35.488-37.215-33.652-33.044-32.878-22.665-24.871-25.16-23.581-22.409-20.443-15.859-19.164
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.3-0.3-0.3-0.3-0.4-0.4-0.4-0.4-0.4-0.4-0.4-0.6-0.6-0.6-0.6-0.5-0.5-0.5-0.5-0.5-0.5-0.3-0.2-0.3-0.4-0.3-0.4-0.4-0.5-0.5-0.4-0.8-0.8-1.0-1.0-1.0-0.9-0.9-0.8-0.6-0.7-0.7-0.6-0.6-0.6-0.5-0.6

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:DerivativeInstrumentRisk, us-gaap:StatementEquityComponents

us-gaap:CommodityContract, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-312011-12-31
Value1.0290.1320.0020.287-0.252-0.26-0.456-0.372-0.3810.0820.328-0.071-0.122-0.27-0.518-0.0680.2580.17-0.2330.2531.9715.5467.0666.9065.5389.26810-0.5080.64.338
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax-4.2-0.5-0.0-1.10.90.91.51.41.5-0.3-1.20.20.30.71.30.2-0.8-0.50.7-0.8-6.2-26.6-78.0-47.3-32.8-65.9-66.62.9-1.7-13.2
Percentage of Assets0.00.00.00.0-0.0-0.0-0.0-0.0-0.00.00.0-0.0-0.0-0.0-0.0-0.00.00.0-0.00.00.00.10.20.20.10.20.2-0.00.00.1
Percentage of Assets us-gaap:CommodityContract us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:InterestRateSwap, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312013-12-312012-12-312011-12-31
Value-11.472-12.035-12.558-13.492-14.035-14.579-15.122-15.668-16.216-16.757-17.307-17.884-18.444-19.005-19.581-16.66-17.124-17.588-18.109-18.282-18.526-10.877-0.341-2.62-3.077-3.58-4.93-6.625-16.313-18.14
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax46.945.745.950.149.449.649.361.061.863.364.347.447.647.647.551.252.052.151.955.558.352.23.817.918.325.532.838.046.055.2
Percentage of Assets-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.2-0.0-0.1-0.1-0.1-0.1-0.2-0.4-0.4
Percentage of Assets us-gaap:InterestRateSwap us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-31
Value-14.003-14.425-14.79-13.717-14.147-14.543-15.077-9.655-9.63-9.784-9.937-19.748-20.197-20.649-21.103-15.838-16.075-16.312-16.541-14.922-15.209-15.494-15.78-22.546-22.969-19.742-20.137-10.145-10.274-9.978-10.289-19.775-19.076
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax57.354.854.151.049.849.549.237.636.737.036.952.452.151.751.248.648.848.447.445.347.974.4174.3154.3136.2140.5133.968.452.853.759.155.758.0
Percentage of Assets-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.1-0.1-0.1-0.1-0.3-0.3-0.3-0.3-0.2-0.2-0.3-0.3-0.2-0.2-0.2-0.3-0.5-0.5-0.5-0.5-0.2-0.3-0.3-0.3-0.5-0.5
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-312009-12-31
Value2988000.02564000.02119000.01710000.01879000.01925000.0267000.01636000.01544000.01432000.02510000.04072000.03642000.03049000.02306000.02448000.02325000.02443000.0791000.01155000.0975000.01573000.01888000.01789000.01771000.01688000.01875000.01841000.01801000.01638000.01968000.01801000.01587000.01549000.02245000.02354000.02177000.02041000.0970000.0810000.0691000.0762000.0309000.0226000.027000.0112000.0224000.0
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.10.00.00.00.10.10.10.10.00.00.00.00.00.00.00.00.0

Stock Issued During Period Value New Issues

us-gaap:StockIssuedDuringPeriodValueNewIssues

us-gaap:StockIssuedDuringPeriodValueNewIssues


Stock
Period End2021-06-302020-03-312019-09-302019-06-302019-03-312018-03-312017-09-302016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value401003050190.00.01449486.8242540.00.00.0
Percentage of StockIssuedDuringPeriodValueNewIssues100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.00.00.00.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StockIssuedDuringPeriodValueNewIssues us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302020-03-312019-09-302019-06-302019-03-31
Value3998294919
Percentage of StockIssuedDuringPeriodValueNewIssues98.598.898.798.798.6
Percentage of Assets0.00.00.00.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.0

us-gaap:CommonStock


Stock
Period End2021-06-302020-03-312019-09-302019-06-302019-03-312015-11-23
Value0.5961.2230.390.6590.28246
Percentage of StockIssuedDuringPeriodValueNewIssues1.51.21.31.31.40.0
Percentage of Assets0.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.0

Minority Interest Decrease From Distributions To Noncontrolling Interest Holders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value4.0614.6444.1163.7794.7413.4854.4054.8465.8623.7574.355.6486.5084.5493.9864.3495.045
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value4.0614.6444.1163.7794.7413.4854.4054.8465.8623.7574.355.6485.6214.5493.9864.3495.045
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.086.4100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value135-386.086122110117191119961131751106814016910856116146951.9028413862111102151846575987254881094792809617247011121-18.2295588
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax36.9-61.325.432.136.136.225.029.734.529.422.021.240.029.623.916.933.926.820.70.625.930.719.541.037.834.322.324.026.721.320.520.931.528.714.837.733.326.34.89.625.927.87.0-7.321.521.3

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-163.513-146.224-231.94-179.999-176.641-173.084-222.938-275.975-172.27-145.027-184.078-118.245-89.972-73.554-61.276-92.598-94.296-69.494-129.546-134.455-108.209-1216.532-119.729-149.536-89.253-117.871-130.826-90.025-93.467-86.829-112.639-91.415-82.315-62.909-87.137135-78.16541-120.145-101.798-103.306-121.758-135.413-90.734-84.971-78.05
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-44.4-23.2-48.1-52.3-54.5-32.6-46.7-85.2-52.2-24.3-36.7-36.9-25.5-12.8-13.5-27.6-27.6-12.7-27.9-40.3-33.2-270.4-37.6-55.0-32.8-26.7-34.6-33.1-33.0-18.9-31.7-35.2-29.4-16.5-27.354.7-32.311.3-33.3-39.7-37.8-30.4-43.0-36.4-33.1-18.7

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1553910945372510018652-39.2928451-73.045-80.656-45.58337-21.496-79.5730.057893668475-10.298108.551552114-1.469332012-49.388-191.897-20.891-18.491-140.1678663762286103-42.0912
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.285.622.613.111.54.821.057.516.0-6.616.916.2-20.7-14.1-10.011.3-6.3-14.50.023.628.8148.6149.3-3.83.71.914.88.15.2-0.39.67.74.4-13.0-60.2-8.5-7.6-38.324.125.028.15.527.641.6-16.42.9

Deferred Income Tax Expense Benefit

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.5390.1539.5892.1014.52521132.4462.33319-9.8437.0234.011-25.4316138.95842-2.3615.9720.02732-5.22-14.531-28.3252220129.561258.9191816201017-6.883187.32-5.4296.0325-13.1638-9.573.492
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Depreciation Depletion And Amortization

us-gaap:DepreciationDepletionAndAmortization

us-gaap:DepreciationDepletionAndAmortization


Depreciation
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value58575556565654515151494948484149484848484744383740393737363635363534334141383733323138303028
Percentage of DepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Inventories

us-gaap:IncreaseDecreaseInInventories

us-gaap:IncreaseDecreaseInInventories


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value11-15.932-13.661811-19.222-6.1781914-29.387-5.4612612-31.196-9.4712714-22.445-6.265228.1-25.822-3.579165.471-25.689-12.6852414-22.291-6.752219.579-18.519-3.25819-1.781-20.828332937-79.717-15.0792041-21.755
Percentage of IncreaseDecreaseInInventories100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Increase Decrease In Other Operating Capital Net

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.4790.355-3.145-2.660.0141.138-2.694-6.1684.657-1.796-4.682-3.3791.0940.2785.4660.897-1.1473.202-6.7733.114-4.6057.4892.6319.618-4.8731.6583.3541.771-3.88-1.9784.447-5.353-4.2984.8925.665-3.6715.348-0.6110-5.4510-4.6139.177-6.111-6.9895.335
Percentage of IncreaseDecreaseInOtherOperatingCapitalNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value135-386.086122110117191119961131751106814016910856116146951.9028413862111102151846575987254881094792809617247011121-18.2295588
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax36.9-61.325.432.136.136.225.029.734.529.422.021.240.029.623.916.933.926.820.70.625.930.719.541.037.834.322.324.026.721.320.520.931.528.714.837.733.326.34.89.625.927.87.0-7.321.521.3

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2596773620936911141038616211333034-13.4832925-10.5257.752263312-8.65931
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.815.316.010.56.517.614.53.64.417.417.35.36.223.29.614.0-5.68.17.1-4.12.86.710.65.0-3.47.5

us-gaap:NetIncomeLoss us-gaap:CumulativeEffectPeriodOfAdoption

srt:CumulativeEffectPeriodOfAdoptionAdjustment


Net
Period End2020-12-31
Value0.0
Percentage of NetIncomeLoss0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax srt:CumulativeEffectPeriodOfAdoptionAdjustment0.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value28100804024977215171079020241365431258021173.28340-14.176-9.943-41.8423330433034-13.4832925-10.5257.7522631
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.715.916.711.77.618.315.34.85.418.018.06.57.023.811.99.47.414.64.65.41.08.9-4.5-3.7-15.47.710.911.39.614.0-5.68.17.1-4.12.86.77.5

us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-0.943-0.911-0.921-1.111-0.993-1.393-1.389-0.647-0.631-0.277-0.468-1.03-1.131-1.488-1.81-0.535-0.458-0.511-0.0990.6361.2193.126
Percentage of ProfitLoss-3.3-0.9-1.1-2.8-4.0-1.4-1.9-4.2-3.6-0.3-0.5-4.9-4.6-1.1-3.3-1.7-1.8-0.6-0.53.637.17.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.3-0.1-0.2-0.3-0.3-0.3-0.3-0.2-0.2-0.0-0.1-0.3-0.3-0.3-0.4-0.2-0.1-0.1-0.00.20.40.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ProfitLoss us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.422-0.365-0.044-0.43-0.396-0.479-0.8390.025-0.154-0.153-0.414-0.449-0.452-0.451-1.273-0.237-0.237-0.229-0.366-0.287-0.2850.2860.4340.4230.4220.4220.130.1290.0980.1480.4170.4170.3640.457
Percentage of ProfitLoss-1.5-0.4-0.1-1.1-1.6-0.5-1.20.2-0.9-0.1-0.5-2.1-1.8-0.3-2.3-0.8-0.9-0.3-1.7-1.6-8.70.7-3.1-4.3-1.01.20.00.00.00.00.00.01.21.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.1-0.0-0.1-0.1-0.1-0.20.0-0.0-0.0-0.1-0.1-0.1-0.1-0.3-0.1-0.1-0.0-0.1-0.1-0.10.10.10.20.20.10.00.00.00.00.10.20.10.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.521-0.546-0.877-0.681-0.597-0.914-0.55-0.672-0.477-0.124-0.054-0.581-0.679-1.037-0.537-0.298-0.221-0.2820.2670.9231.504-3.412-3.092-0.948-1.261-1.241-0.1911.3281.4030.780.9511.4261.2010.468
Percentage of ProfitLoss-1.8-0.5-1.1-1.7-2.4-0.9-0.8-4.4-2.7-0.1-0.1-2.8-2.7-0.8-1.0-0.9-0.9-0.41.25.245.8-8.521.89.53.0-3.70.00.00.00.00.00.03.91.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.1-0.1-0.2-0.2-0.2-0.2-0.1-0.2-0.1-0.0-0.0-0.2-0.2-0.2-0.1-0.1-0.1-0.10.10.30.5-0.8-1.0-0.3-0.5-0.3-0.10.50.50.20.30.50.40.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value3.1264.1714.0663.7284.053.6553.113.554
Percentage of ProfitLoss11.14.210.115.14.223.717.63.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.80.71.21.10.81.10.90.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value25963620931114103
Percentage of ProfitLoss88.995.889.984.995.876.382.496.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.815.310.56.517.63.64.417.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.0

Share Based Compensation

us-gaap:ShareBasedCompensation

us-gaap:ShareBasedCompensation


Share
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.7873.2572.6771.5830.8220.2913.7631.2393.7973.2964.8462.3233.0122.2090.0321.0053.4983.0911.7612.072.5934.4611.208-0.231.0152.0832.3510.073.1923.7163.4952.2043.1183.7782.2972.7051.4521.8170.7121.6720.8892.372.9410.9370.9820.989
Percentage of ShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-163.513-146.224-231.94-179.999-176.641-173.084-222.938-275.975-172.27-145.027-184.078-118.245-89.972-73.554-61.276-92.598-94.296-69.494-129.546-134.455-108.209-1216.532-119.729-149.536-89.253-117.871-130.826-90.025-93.467-86.829-112.639-91.415-82.315-62.909-87.137135-78.16541-120.145-101.798-103.306-121.758-135.413-90.734-84.971-78.05
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-44.4-23.2-48.1-52.3-54.5-32.6-46.7-85.2-52.2-24.3-36.7-36.9-25.5-12.8-13.5-27.6-27.6-12.7-27.9-40.3-33.2-270.4-37.6-55.0-32.8-26.7-34.6-33.1-33.0-18.9-31.7-35.2-29.4-16.5-27.354.7-32.311.3-33.3-39.7-37.8-30.4-43.0-36.4-33.1-18.7

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value17314623118717617122527417314417912186696992946914013411583106142881171081129383115928363871128167
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1553910945372510018652-39.2928451-73.045-80.656-45.58337-21.496-79.5730.057893668475-10.298108.551552114-1.469332012-49.388-191.897-20.891-18.491-140.1678663762286103-42.0912
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.285.622.613.111.54.821.057.516.0-6.616.916.2-20.7-14.1-10.011.3-6.3-14.50.023.628.8148.6149.3-3.83.71.914.88.15.2-0.39.67.74.4-13.0-60.2-8.5-7.6-38.324.125.028.15.527.641.6-16.42.9

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-01-132016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-12-312013-09-302012-12-312012-09-302011-12-312010-12-31
Value0.00.07000.00.07000.00.00.00.00.01192285465450.00.03000.01600.05250.00.00.00.00.0
Percentage of ProceedsFromIssuanceOfLongTermDebt0.00.0100.00.00.0100.00.00.00.00.00.0100.0100.0100.0100.00.00.0100.00.0100.00.0100.00.00.00.00.00.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.01.4361.4341.4361.4364.2916011.4363011.4362516001.4351.4361.43651511.4361.4361121410.00.00.00.0120.00.03392.3941021.7372281.2298.5211.8972.2132.1171.8972.1552.3761.0622333
Percentage of RepaymentsOfLongTermDebt0.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Payments Of Dividends

us-gaap:PaymentsOfDividends

us-gaap:PaymentsOfDividends


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value35353533333232303030302525252523232322212121181818181717171716161616161616161613151414141414
Percentage of PaymentsOfDividends100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-30
Value2.00.5-1.710.30.1640.141-0.0140.140.1150.139-0.0260.2550.194-0.228-0.0360.3040.2910.294-0.0420.2710.0860.0960.041-0.5480.3270.3440.0040.298
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value408360311336535450475413308263
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value313309336330414551415340386413
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value1312119.1219.2634.3045.0171.8066.1920.773
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Proceeds From Repayments Of Short Term Debt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value14984-319.125-30.37554192-62.15-20.9773-9.7-42.4-47.1-13.8711757-45.65210.0-140.6138
Percentage of ProceedsFromRepaymentsOfShortTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0

bkh:AmountRecoveredThroughRegulatoryMechanism us-gaap:UnusualOrInfrequentItem

bkh:AmountRecoveredThroughRegulatoryMechanism

bkh:WinterStormUri


Amount
Period End2021-06-30
Value4600000.0
Percentage of AmountRecoveredThroughRegulatoryMechanism100.0

bkh:AnnualTCJARelatedCustomerBillingCredits dei:LegalEntity, us-gaap:RegulatoryAgency

bkh:AnnualTCJARelatedCustomerBillingCredits

bkh:BlackHillsEnergyColoradoElectric, bkh:ColoradoPublicUtilitiesCommissionCPUC


Annual
Period End2021-04-30
Value900000.0
Percentage of AnnualTCJARelatedCustomerBillingCredits100.0

bkh:AtTheMarketEquityProgramProceedsfromSaleofStock us-gaap:StatementEquityComponents

bkh:AtTheMarketEquityProgramProceedsfromSaleofStock

us-gaap:CommonStock


At
Period End2021-06-302019-12-312019-09-302019-06-302016-12-312016-09-302016-06-30
Value400.03049134949
Percentage of AtTheMarketEquityProgramProceedsfromSaleofStock100.00.0100.0100.0100.0100.0100.0

bkh:AtTheMarketEquityProgramStockIssuedIssuanceCosts us-gaap:StatementEquityComponents

bkh:AtTheMarketEquityProgramStockIssuedIssuanceCosts

us-gaap:AdditionalPaidInCapital


At
Period End2021-06-30
Value400000.0
Percentage of AtTheMarketEquityProgramStockIssuedIssuanceCosts100.0

bkh:EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit dei:LegalEntity

bkh:EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit

bkh:ColoradoElectric


Effective
Period End2021-03-31
Value7600000.0
Percentage of EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit100.0

bkh:ColoradoElectricAndNebraskaGas


Effective
Period End2021-06-30
Value10000000.0
Percentage of EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit0.0

bkh:NebraskaGas


Effective
Period End2021-06-30
Value2200000.0
Percentage of EffectiveIncomeTaxRateReconciliationTaxCutsAndJobsActOf2017AmountTaxBenefitFromBillCredit0.0

bkh:EffectiveIncomeTaxReconciliationTaxBenefitFromAmortizationOfExcessDeferredIncomeTaxes

bkh:EffectiveIncomeTaxReconciliationTaxBenefitFromAmortizationOfExcessDeferredIncomeTaxes


Effective
Period End2021-06-302021-03-31
Value-100000.01500000.0
Percentage of EffectiveIncomeTaxReconciliationTaxBenefitFromAmortizationOfExcessDeferredIncomeTaxes100.0100.0

bkh:EffectiveIncomeTaxReconciliationTaxFlowThroughBenefitFromRepairsAndIndirectCosts

bkh:EffectiveIncomeTaxReconciliationTaxFlowThroughBenefitFromRepairsAndIndirectCosts


Effective
Period End2021-06-30
Value1900000.0
Percentage of EffectiveIncomeTaxReconciliationTaxFlowThroughBenefitFromRepairsAndIndirectCosts100.0

bkh:FuelPurchasedPowerAndCostOfGasSold

bkh:FuelPurchasedPowerAndCostOfGasSold


Fuel
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value108293711871597389248193801042471598698219162808417110671732051658410123015371991681236263157174861032101468697
Percentage of FuelPurchasedPowerAndCostOfGasSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:FuelPurchasedPowerAndCostOfGasSold us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:CommodityContract, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Fuel
Period End2021-06-302021-03-312020-06-302020-03-312019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value0.056-0.031-0.07-0.4860.0830.5540.672-0.018-0.163-0.621-0.223-0.034-0.0440.0580.0090.128-0.0610.0570.00.00.00.0
Percentage of FuelPurchasedPowerAndCostOfGasSold0.1-0.0-0.1-0.30.10.20.3-0.0-0.2-0.3-0.1-0.0-0.00.00.00.2-0.10.00.00.00.00.0

bkh:IncomeStatementImpacts dei:LegalEntity, us-gaap:IncomeStatementLocation, us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem

bkh:IncomeStatementImpacts

bkh:BlackHillsEnergyServices, bkh:NonRecoverableFuelCosts, bkh:GasUtilities, bkh:WinterStormUri


Income
Period End2021-03-31
Value8.2
Percentage of IncomeStatementImpacts100.0

bkh:IncomeStatementImpacts us-gaap:IncomeStatementLocation, us-gaap:StatementBusinessSegments, us-gaap:UnusualOrInfrequentItem

bkh:NonRecoverableFuelCosts, bkh:ElectricUtilities, bkh:WinterStormUri


Income
Period End2021-03-31
Value2.1
Percentage of IncomeStatementImpacts25.6

bkh:WholesalePowerMarginImpacts, bkh:ElectricUtilities, bkh:WinterStormUri


Income
Period End2021-03-31
Value3.2
Percentage of IncomeStatementImpacts39.0

us-gaap:OperatingIncomeLoss, bkh:PowerGeneration, bkh:WinterStormUri


Income
Period End2021-03-31
Value-1.7
Percentage of IncomeStatementImpacts-20.7

bkh:IncomeStatementImpacts us-gaap:IncomeStatementLocation, us-gaap:UnusualOrInfrequentItem

us-gaap:InterestExpense, bkh:WinterStormUri


Income
Period End2021-03-31
Value0.7
Percentage of IncomeStatementImpacts8.5

bkh:IncomeStatementImpacts us-gaap:UnusualOrInfrequentItem

bkh:WinterStormUri


Income
Period End2021-03-31
Value12
Percentage of IncomeStatementImpacts152.4

bkh:IncomeTaxBenefitFromRelievedTCJARelatedLiabilities

bkh:IncomeTaxBenefitFromRelievedTCJARelatedLiabilities


Income
Period End2020-09-30
Value3500000.0
Percentage of IncomeTaxBenefitFromRelievedTCJARelatedLiabilities100.0

bkh:IncrementalFuelPurchasedPowerAndNaturalGasCosts us-gaap:UnusualOrInfrequentItem

bkh:IncrementalFuelPurchasedPowerAndNaturalGasCosts

bkh:WinterStormUri


Incremental
Period End2021-03-31
Value571
Percentage of IncrementalFuelPurchasedPowerAndNaturalGasCosts100.0

bkh:NetPaymentsBorrowingsOfRevolvingCreditFacilityAndCommercialPaperProgram

bkh:NetPaymentsBorrowingsOfRevolvingCreditFacilityAndCommercialPaperProgram


Net
Period End2021-06-302021-03-312020-06-302020-03-31
Value13980000.0-18170000.0-319120000.0-30375000.0
Percentage of NetPaymentsBorrowingsOfRevolvingCreditFacilityAndCommercialPaperProgram100.0100.0100.0100.0

bkh:OperatingExpenseMaintenanceOperationsandOtherCostsandExpense

bkh:OperatingExpenseMaintenanceOperationsandOtherCostsandExpense


Operating
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value12312911712512911712412313111511811610011411712212111511210787899093
Percentage of OperatingExpenseMaintenanceOperationsandOtherCostsandExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:OperatingExpenseMaintenanceOperationsandOtherCostsandExpense us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Operating
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value0.0240.0250.0250.030.0180.020.020.0190.0450.0440.0440.0450.0220.0490.0490.048-0.055-0.055-0.055-0.055-0.055-0.055
Percentage of OperatingExpenseMaintenanceOperationsandOtherCostsandExpense0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0-0.0-0.0-0.1-0.1-0.1-0.1

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Operating
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-31
Value-0.597-0.598-0.597-0.597-0.22-0.084-0.221-0.22-0.622-0.621-0.622-0.622-0.357-0.414-0.414-0.4140.4940.4940.4940.7060.7050.705
Percentage of OperatingExpenseMaintenanceOperationsandOtherCostsandExpense-0.5-0.5-0.5-0.5-0.2-0.1-0.2-0.2-0.5-0.5-0.5-0.5-0.4-0.4-0.4-0.30.40.40.50.80.80.8

bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency

bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC


Public
Period End2021-03-01
Value4600000.0
Percentage of PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates100.0

bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC, us-gaap:SubsequentEvent


Public
Period End2021-01-26
Value4600000.0
Percentage of PublicUtilitiesAmountOfSystemSafetyAndIntegretyRiderMovedToBaseRates0.0

bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency

bkh:PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested

bkh:BlackHillsEnergyIowaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:IowaUtilitiesBoardIUB


Public
Period End2021-06-01
Value2200000.0
Percentage of PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested100.0

bkh:BlackHillsEnergyKansasGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:KansasCorporationCommissionKCC


Public
Period End2021-05-07
Value4900000.0
Percentage of PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested0.0

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewApprovedByRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC


Public
Period End2021-03-01
Value4600000.0
Percentage of PublicUtilitiesAmountOfSystemSafetyAndIntegrityRiderMovedToBaseRatesRequested0.0

bkh:SubsequentEventEstimatedCostOfIncrementalGasPurchasesDueToHistoricColdWeatherEvent us-gaap:SubsequentEventType

bkh:SubsequentEventEstimatedCostOfIncrementalGasPurchasesDueToHistoricColdWeatherEvent

us-gaap:SubsequentEvent


Subsequent
Period End2021-02-24
Value600
Percentage of SubsequentEventEstimatedCostOfIncrementalGasPurchasesDueToHistoricColdWeatherEvent100.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts


Adjustments
Period End2021-06-302020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value0.4660.1190.0790.9670.3980.4920.289
Percentage of AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts100.0100.0100.0100.0100.0100.0100.0

us-gaap:AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Adjustments
Period End2021-06-302020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value0.4660.1190.0790.9670.3980.4920.289
Percentage of AdjustmentsToAdditionalPaidInCapitalStockIssuedIssuanceCosts100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivableRecoveries

us-gaap:AllowanceForDoubtfulAccountsReceivableRecoveries


Allowance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value772000.01014000.01008000.01517000.01281000.0922000.01200000.0872000.0
Percentage of AllowanceForDoubtfulAccountsReceivableRecoveries100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs


Allowance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value2.6271.6433.072.2492.0541.7232.0733.523
Percentage of AllowanceForDoubtfulAccountsReceivableWriteOffs100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AmortizationOfFinancingCostsAndDiscounts

us-gaap:AmortizationOfFinancingCostsAndDiscounts


Amortization
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value2167000.02214000.02360000.01277000.02009000.02237000.01512000.02107000.02212000.02007000.02163000.01988000.01794000.01900000.02049000.02074000.02448000.01690000.02178000.01145000.01191000.01666000.03290000.01955000.0600000.0519000.0519000.0501000.0539000.0568000.03554000.01021000.01093000.01095000.0254000.01251000.01331000.02719000.0615000.01841000.01671000.01528000.0
Percentage of AmortizationOfFinancingCostsAndDiscounts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CapitalExpendituresIncurredButNotYetPaid


Capital
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value2.53451-14.259266.905534.833.175265619121521-6.874-2.5369.24328-15.058-8.7772230-12.064153.127330.111-0.32840122.2141331-3.747-12.9012031-12.037152.13632115.454
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-12.1917.186-0.473-24.501-22.45144-3.1176.531-5.475-8.426101.528-22.191152.1082.070.362-2.092
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths

bkh:InterestRateSwapAndCommodityDerivative, us-gaap:CashFlowHedging


Cash
Period End2021-06-302021-03-31
Value1900000.0900000.0
Percentage of CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths100.0100.0

us-gaap:CommonStockDividendsPerShareCashPaid

us-gaap:CommonStockDividendsPerShareCashPaid


Common
Period End2021-06-302021-03-312020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.5650.5650.5350.5350.5050.5050.5050.4750.4750.4750.4750.4450.4450.4450.420.420.420.420.4050.4050.4050.4050.390.390.390.390.380.380.380.380.370.370.370.370.3650.3650.3650.3650.360.360.360.36
Percentage of CommonStockDividendsPerShareCashPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-117000.0-117000.0-5000.0-5000.0-5000.0-5000.00000-54000.0-54000.0-54000.0-54000.0-124000.0-125000.0-125000.0-125000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-1829000.0-1829000.0-2093000.0-2093000.0-2093000.0-2093000.0-941000.0-941000.0-940000.0-941000.0-2159000.0-2158000.0-2157000.0-2158000.0-1002000.0-1002000.0-1001000.0-1002000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses1563.21563.241860.041860.041860.041860.00.00.00.00.03998.13996.33994.43996.3808.1801.6800.8801.6

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value-438000.0-439000.0-425000.0-426000.0-426000.0-134000.0-134000.0-134000.0-250000.0-250000.0-250000.0-251000.0-250000.0-250000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses374.4375.28500.08520.08520.00.00.00.0463.0463.0463.0200.8200.0200.0

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-109000.0-109000.0-136000.0-136000.0-137000.0-137000.0-100000.0-99000.0-100000.0-99000.0-101000.0-99000.0-99000.0-99000.0-84000.0-109000.0-109000.0-109000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2020-09-302020-06-302019-09-302019-06-302018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value1000.0001000.001000.00001000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit-0.7-0.0-0.0-1.0-0.0-1.0-0.0-0.0-0.0-0.9

us-gaap:DefinedBenefitPlanContributionsByEmployer us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanContributionsByEmployer

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value1.3811.3820.3681.3361.3351.3352.1351.1091.1081.109-0.1591.2341.2341.234
Percentage of DefinedBenefitPlanContributionsByEmployer100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.00.0120.00.0120.00.00.0120.00.0
Percentage of DefinedBenefitPlanContributionsByEmployer0.00.0951.30.00.01145.20.00.0-0.01029.20.00.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.4820.4821.6090.3550.3550.3551.2460.3660.3660.3661.0440.3430.3430.343
Percentage of DefinedBenefitPlanContributionsByEmployer34.934.9437.226.626.626.658.433.033.033.0-656.627.827.827.8

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.0340.0340.0450.0460.0460.0450.0580.0570.0580.0570.1450.0570.0560.0570.0780.0790.0790.079
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value5.2195.2195.6485.6475.6485.6486.1016.16.16.16.1866.1856.1856.1856.1296.136.1296.129
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets15350.015350.012551.112276.112278.312551.110519.010701.810517.210701.84266.210850.911044.610850.97857.77759.57758.27758.2

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.2640.2650.4120.4120.4130.4120.5640.560.5630.560.5220.5210.5210.5210.5410.5330.5340.533
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value2.3282.3283.3573.3563.3563.3574.3434.3444.3444.3433.8683.8673.8683.8673.883.883.883.88
Percentage of DefinedBenefitPlanInterestCost881.8878.5814.8814.6812.6814.8770.0775.7771.6775.5741.0742.2742.4742.2717.2728.0726.6728.0

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.1770.1770.2750.2740.2750.2750.3230.3240.3240.3240.2920.2930.2920.2930.3190.3190.3190.319
Percentage of DefinedBenefitPlanInterestCost67.066.866.766.566.666.757.357.957.557.955.956.256.056.259.059.859.759.8

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.7970.7980.750.7490.7490.7490.8590.8580.8590.8580.9030.9920.9920.9921.0781.0451.0461.045
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.1980.1971.1551.1541.1541.1550.5360.5370.5360.5361.5641.5631.5631.5630.5250.5260.5260.525
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost24.824.7154.0154.1154.1154.262.462.662.462.5173.2157.6157.6157.648.750.350.350.2

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value1.6351.3091.7352.518-0.6690.8871.1511.7431.1750.9780.8231.1821.1781.397
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost205.1164.0231.6336.2-89.3103.4134.0203.1118.498.683.0113.1112.6133.7

us-gaap:DefinedBenefitPlanServiceCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value559000.0559000.0514000.0514000.0514000.0514000.0453000.0454000.0454000.0454000.0573000.0573000.0572000.0573000.0575000.0575000.0575000.0575000.0
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1260000.01259000.01353000.01352000.01353000.01353000.01346000.01346000.01345000.01346000.01709000.01708000.01709000.01708000.01758000.01759000.01759000.01758000.0
Percentage of DefinedBenefitPlanServiceCost225.4225.2263.2263.0263.2263.2297.1296.5296.3296.5298.3298.1298.8298.1305.7305.9305.9305.7

us-gaap:SupplementalEmployeeRetirementPlanDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1020000.0693000.097000.01035000.01817000.0-1370000.02589000.0429000.0692000.01285000.0417000.0632000.0435000.0280000.0889000.0612000.0609000.0827000.0
Percentage of DefinedBenefitPlanServiceCost182.5124.018.9201.4353.5-266.5571.594.5152.4283.072.8110.376.048.9154.6106.4105.9143.8

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:Energy, us-gaap:HedgingDesignation, us-gaap:IncomeStatementLocation

us-gaap:DerivativeGainLossOnDerivativeNet

bkh:NaturalGasDistribution, us-gaap:Nondesignated, us-gaap:CostOfSales


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value1.8160.3661.7770.4490.766-0.02-1.1850.025
Percentage of DerivativeGainLossOnDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Electricity, us-gaap:Nondesignated, us-gaap:CostOfSales


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value-3.598-1.5240.372-1.386-0.2041.3620.1420.00.0
Percentage of DerivativeGainLossOnDerivativeNet-198.1-416.40.0-78.0-45.4177.8-710.0-0.00.0

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:HedgingDesignation

us-gaap:Nondesignated


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1.782-1.158-0.980.3910.2452.128-0.0620.122-1.1850.0250.172-0.0960.7710.254-0.475-0.375-0.665-0.692-1.602-0.3422.2010.634
Percentage of DerivativeGainLossOnDerivativeNet-98.1-316.40.022.054.6277.80.0-610.0100.0100.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet

us-gaap:CommodityContract, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.1870.173-0.4190.6910.0110.2570.0910.129-0.083-0.554-0.6720.0180.1630.6210.264-0.261-0.386-0.287-15.464-2.329-3.226-3.649
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateSwap, us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.7130.7130.7130.7120.7130.7130.7120.7130.7130.7130.7130.7120.7130.7130.7130.7130.7130.7121.0471.1620.84-1.709
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet60.1412.1-170.2103.06481.8277.4782.4552.7-859.0-128.7-106.13955.6437.4114.8270.1-273.2-184.7-248.1-6.8-49.9-26.046.8

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:IncomeStatementLocation

us-gaap:CommodityContract, us-gaap:CashFlowHedging, us-gaap:CostOfSales


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.056-0.031-0.178-0.07-0.486-0.1290.0830.554-0.018-0.163-0.621-0.223-0.034-0.0440.058-0.037-0.1280.0610.057
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet4.7-17.9-25.8-636.4-189.1-100.0-100.0-100.0-100.0-100.0-100.0-84.513.011.4-20.20.25.5-1.9-1.6

us-gaap:InterestRateSwap, us-gaap:CashFlowHedging, us-gaap:InterestExpense


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312011-09-30
Value-0.713-0.713-0.712-0.713-0.713-0.713-0.713-0.713-0.712-0.713-0.713-0.713-0.713-0.713-0.712-6.4290.840.841.7098.356-1.603-1.671.4376.414-0.925-0.926-0.89412-1.844-1.82-1.796-2.089-1.853-1.923-1.93
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet-60.1-412.1-103.0-6481.8-277.4-552.7859.0128.7-3955.6-437.4-114.8-270.1273.2184.7248.141.6-36.1-26.0-46.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship

us-gaap:CashFlowHedging


Derivative
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value-0.657-0.744-0.89-0.783-1.199-0.842-0.63-0.159-0.73-0.876-1.334-0.977-0.452-0.327-0.42513-1.489-2.3865.358-16.8111.5061.996-2.49511-2.06-2.177-1.20510-2.012-1.848-0.704-1.046-0.0151.0511.1870.715-0.414-1.617-0.8616.7312-8.71
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet-55.3-430.1-128.8-7118.2-466.5-652.7759.028.7-4055.6-537.4-214.8-370.1173.284.7148.1-88.563.974.0-146.80.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship, us-gaap:HedgingDesignation

us-gaap:CashFlowHedging, us-gaap:DesignatedAsHedgingInstrument


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value1.90.8860.2941.4030.7240.970.6890.6920.1120.393
Percentage of DerivativeInstrumentsGainLossReclassifiedFromAccumulatedOCIIntoIncomeEffectivePortionNet160.1512.1-70.2203.06581.8377.4757.1536.4-134.9-70.9

us-gaap:DividendsCommonStockCash

us-gaap:DividendsCommonStockCash


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value353533333230303030252525252323232221212118181818
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3535333332303030252525
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeTaxReconciliationDeductionsQualifiedProductionActivities us-gaap:PublicUtility

us-gaap:IncomeTaxReconciliationDeductionsQualifiedProductionActivities

bkh:WindAssets


Income
Period End2021-06-302021-03-31
Value300000.01300000.0
Percentage of IncomeTaxReconciliationDeductionsQualifiedProductionActivities100.0100.0

us-gaap:IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets

us-gaap:IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-100.1121186-2.658-65.131-8.171107-15.4-115.78215118-21.35-75.82425102-9.124-56.85-41.0521073.492-54.802-27.55935-12.794-15.225-47.94765-5.79-72.7257842-0.385-37.5439.16629-1.185-32.823-9.4397.34121-57.2065.591
Percentage of IncreaseDecreaseInAccountsReceivableAndOtherOperatingAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities

us-gaap:IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-36.038-23.6023551-19.788-43.2974824-65.874-41.689919.79-25.245-71.1497312-14.059-99.48261-16.732-17.322-68.1014.18561-21.642-44.6523010-54.05229392.965-13.102-13.6371132-12.647-42.368424.337-4.524-73.3025228-25.295-24.716
Percentage of IncreaseDecreaseInOtherAccountsPayableAndAccruedLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherRegulatoryAssets

us-gaap:IncreaseDecreaseInOtherRegulatoryAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value7.7035337.00119-1.208-20.679-11.1643.661-3.085-13.0318.04713-7.734-47.903161.799-2.85-0.2364.839-6.59110-12.8565.885-0.59-6.906-20.272-4.9530.123-9.4632.68-1.011-15.3090.7769.6669.6721.937-33.96619-0.6016.083-3.277
Percentage of IncreaseDecreaseInOtherRegulatoryAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInRegulatoryLiabilities

us-gaap:IncreaseDecreaseInRegulatoryLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-4.218-5.2916.98-18.0-1.0021.3160.486-9.296-4.713-1.635-2.8831.4263.89216-0.208-10.236-3.1759.083-5.901-11.175-8.61911-0.782-4.833-6.431132.2120.00.3745.177-1.598-19.323186.157-6.5321.5899.984-7.126-6.225102.834
Percentage of IncreaseDecreaseInRegulatoryLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements


Incremental
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value51000.058000.09000.055000.044000.078000.016000.0128000.0139000.0140000.066000.0111000.0108000.070000.0-58000.0174000.0178000.0185000.08000.0135000.0110000.094000.0000119000.02000.0193000.0189000.0224000.04000.0256000.0240000.0259000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestCostsIncurred

us-gaap:InterestCostsIncurred


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value3837363635353736363536363535353535353537343224221919191717174323232332272729282928292627
Percentage of InterestCostsIncurred100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestCostsIncurred us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:InterestRateSwap, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-03-31
Value-0.713-0.713-0.713-0.712-0.713-0.713-0.712-0.713-0.713-0.713-0.713
Percentage of InterestCostsIncurred-1.8-1.9-1.9-1.9-2.0-2.0-1.9-2.0-2.0-2.0-2.0

us-gaap:InvestmentIncomeInterest

us-gaap:InvestmentIncomeInterest


Investment
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.4670.2250.4330.480.220.3280.4240.5130.3960.2990.6290.3820.320.310.3160.4020.2570.041-1.0840.9120.9460.6550.4580.4140.3010.4480.3840.5750.5760.390.3980.5650.4750.2850.5290.3640.6270.4370.4190.5630.4750.560.1650.1990.0840.246
Percentage of InvestmentIncomeInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherAssetImpairmentCharges

us-gaap:OtherAssetImpairmentCharges


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value0.00.00.06.8590.0190.00.00.00.0
Percentage of OtherAssetImpairmentCharges0.00.00.0100.00.0100.00.00.00.00.0

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-06-302019-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-1117000.00055000.000-1738000.00002684000.000-27000.0-10588000.000-2000.08237000.0000
Percentage of OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodNetOfTax100.00.00.0100.00.00.0100.00.00.00.0100.00.00.0100.0100.00.00.0100.0100.00.00.00.0

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value00-208000.00017000.0-1886000.0000-757000.00001391000.000-15000.0-5002000.000-2000.03813000.0000
Percentage of OtherComprehensiveIncomeDefinedBenefitPlansNetUnamortizedGainLossArisingDuringPeriodTax0.00.0100.00.00.0100.0100.00.00.00.0100.00.00.00.0100.00.00.0100.0100.00.00.0100.0100.00.00.00.0

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-18000.0-16000.0-20000.0-18000.0-19000.0-23000.0-13000.0-16000.0-15000.0-14000.0-31000.0-34000.0-35000.0-35000.0-34000.0-32000.0-31000.0-31000.0-46000.0-36000.0-36000.0-36000.0-42000.0-36000.0-36000.0-36000.0-31000.0-31000.0-70000.0-9000.0-42000.0-41000.0364000.0-46000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax

us-gaap:OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-4000.0-6000.0-6000.0-7000.0-6000.0-3000.0-5000.0-5000.0-14000.0-10000.0-9000.0-10000.0-17000.0-17000.0-18000.0-17000.0-9000.0-19000.0-19000.0-19000.0-30000.0-19000.0-19000.0-19000.0-16000.0-17000.0-39000.0-4000.0-119000.0-22000.0268000.0-17000.0
Percentage of OtherComprehensiveIncomeLossAmortizationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetPriorServiceCostCreditTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax us-gaap:DerivativeInstrumentRisk, us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:CommodityContract, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.9390.107-0.2280.401-0.045-0.175-0.088-0.115-0.3990.180.9230.030.03-0.228-0.524-0.160.3310.5840.056-0.249-1.321.152
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Other
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1.1170.00.00.055-6.2610.00.00.02.1550.00.00.0-1.890.00.00.0-1.9850.00.00.0
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax489.90.0-0.0-31.47114.8-0.0-0.00.0233.50.00.0-0.0360.7-0.00.00.0-3544.6-0.0-0.00.0

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.9390.107-1.3450.401-0.045-0.12-6.349-0.115-0.3990.183.0780.030.03-0.228-2.414-0.160.2730.642-2.031-0.551-11.422-8.644
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0589.9100.0100.068.67214.8100.0100.0100.0333.5100.0100.0100.0460.7100.082.5109.9-3626.8221.3865.3-750.3

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect


Other
Period End2021-06-302021-03-312020-06-302020-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value6000.09000.06000.07000.0000073000.000-90000.088000.0000
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansBenefitPlanImprovementTaxEffect100.0100.0100.0100.00.00.00.00.0100.00.00.0100.0100.00.00.00.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax us-gaap:DerivativeInstrumentRisk

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax

us-gaap:CommodityContract


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value42000.0-23000.057000.0-137000.0-54000.0-371000.0-4000.0-124000.064000.0426000.0516000.0-21000.0-118000.0-476000.0-74000.0166000.0243000.0181000.01157000.01469000.02050000.02301000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateSwap


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-563000.0-523000.0-934000.0-544000.0-543000.0-543000.0-546000.0-548000.0-541000.0-550000.0-570000.0-560000.0-561000.0-561000.0-463000.0-464000.0-464000.0-463000.0-890000.0-546000.0-546000.01111000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesNetOfTax-1340.52273.9-1638.6397.11005.6146.413650.0441.9-845.3-129.1-110.52666.7475.4117.9625.7-279.5-190.9-255.8-76.9-37.2-26.648.3

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax us-gaap:DerivativeInstrumentRisk

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax

us-gaap:CommodityContract


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-14000.0-8000.076000.0-41000.0-16000.0-115000.0-87000.0-5000.019000.0128000.0156000.03000.0-45000.0-145000.0-190000.095000.0143000.0106000.0730000.0860000.01176000.01348000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateSwap


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value150000.0-190000.0221000.0-168000.0-170000.0-170000.0-166000.0-165000.0-172000.0-163000.0-143000.0-152000.0-152000.0-152000.0-250000.0-249000.0-249000.0-249000.0-479000.0-294000.0-294000.0598000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIOnDerivativesTax-1071.42375.0290.8409.81062.5147.8190.83300.0-905.3-127.3-91.7-5066.7337.8104.8131.6-262.1-174.1-234.9-65.6-34.2-25.044.4

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-440000.0-381000.0-64000.0-448000.0-415000.0-502000.0-852000.09000.0-169000.0-167000.0-445000.0-483000.0-487000.0-486000.0-275000.0-269000.0-268000.0-260000.0-412000.0-323000.0-321000.0-322000.0-476000.0-459000.0-458000.0-458000.0-161000.0-160000.0-168000.0-157000.0-459000.0-458000.00-503000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansForNetGainLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax

us-gaap:OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-31
Value-157000.0217000.01384000.0-149000.0-182000.095000.0-631000.092000.052000.053000.0177000.0138000.0135000.0136000.0140000.0145000.0146000.0154000.0171000.0173000.0172000.0
Percentage of OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIPensionAndOtherPostretirementBenefitPlansTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax us-gaap:DerivativeInstrumentRisk

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax

us-gaap:CommodityContract


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value939000.0107000.0-228000.0401000.0-45000.0-175000.0-88000.0-115000.0-399000.0180000.0923000.030000.030000.0-228000.0-524000.0-160000.0331000.0584000.056000.0-249000.0-1546000.01152000.0
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax us-gaap:DerivativeInstrumentRisk

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax

us-gaap:CommodityContract


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value304000.035000.0-58000.0112000.0-14000.0-54000.0-26000.0-35000.0-119000.054000.0279000.0018000.0-69000.0-307000.0-94000.0194000.0342000.0-536000.0423000.0-906000.0675000.0
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCostAndExpenseOperating

us-gaap:OtherCostAndExpenseOperating


Other
Period End2020-09-302019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value1221160.3930.44-0.1520.2220.5251.492.5120.1641.1681.9699.6056.7487.551264.0912.3740.9660.0520.1770.0490.1490.1250.1520.090.5290.4720.3730.2160.2671.1960.1480.2590.0520.9660.2270.0830.369
Percentage of OtherCostAndExpenseOperating100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCostAndExpenseOperating us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetPriorServiceCostCredit


Other
Period End2020-09-302019-09-30
Value0.0240.019
Percentage of OtherCostAndExpenseOperating0.00.0

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustmentNetUnamortizedGainLoss


Other
Period End2020-09-302019-09-30
Value-0.597-0.083
Percentage of OtherCostAndExpenseOperating-0.5-0.1

us-gaap:OtherNoncashIncomeExpense

us-gaap:OtherNoncashIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value-4344000.0-6151000.0-3759000.0-4231000.0-2787000.0-892000.0-7293000.0-201000.0-4563000.0-4428000.01832000.0-2784000.0-1831000.0-3053000.0-777000.0-965000.04212000.02303000.03442000.0361000.0-3285000.05000000.08885000.0-293000.03028000.0-6748000.0-12399000.0-535000.03709000.0-5190000.0-392000.0-467000.0-5353000.0-3614000.0754000.0753000.0-2071000.0-2187000.0-900000.0-5998000.0-7144000.03440000.010514000.0-3283000.0
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromOtherInvestingActivities


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-9.661-0.0780.529-7.6810.211.202-2.9011.124-1.290.9017.047-3.1390.1120.261-0.7150.228-0.1630.1850.2790.2110.320.329-8.2516.5370.3040.3480.289-0.63-0.2263.22-2.625-0.84-0.976-1.035.237-0.962-2.99-1.1055.584-0.252-0.013-0.786-11.133-0.034-7.1042.865
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToMinorityShareholders

us-gaap:PaymentsToMinorityShareholders


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-31
Value4.0614.6443.2034.1163.7794.7415.1653.4854.4054.8465.8623.7574.355.6485.5134.5493.9864.3495.0454.5160.00.00.0
Percentage of PaymentsToMinorityShareholders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:PensionAndOtherPostretirementBenefitExpense

us-gaap:PensionAndOtherPostretirementBenefitExpense


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value2.632.3042.7033.6384.4211.2354.4412.2822.5463.1373.4273.733.5333.3781.6712.7532.4753.2422.4614.0484.3163.4665.4414.7085.1845.2833.7053.73.7063.7035.555.5485.5485.5485.2365.2455.2465.2463.6563.6433.6453.6424.1284.0714.2033.94
Percentage of PensionAndOtherPostretirementBenefitExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionContributions

us-gaap:PensionContributions


Pension
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312017-12-312017-09-302016-12-312016-09-302015-12-312015-09-302014-12-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value0.00.00.0120.00.0270.04.00.0100.00.0120.00.00.350.00.0250.0100.550.00.030
Percentage of PensionContributions0.00.00.0100.00.00.0100.00.0100.00.0100.00.00.0100.00.00.0100.00.00.0100.00.0100.0100.00.00.0100.0

us-gaap:ProceedsFromIncomeTaxRefunds

us-gaap:ProceedsFromIncomeTaxRefunds


Proceeds
Period End2020-12-31
Value0
Percentage of ProceedsFromIncomeTaxRefunds0.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-0.038-0.1190.11499-0.0032951192990.0050.7020.3720.8460.5970.7942.1711350497.8212460.7820.7030.9990.8580.70.8120.8810.7481.0361.3391.2310.8912.3250.7460.7641200.7620.8320.6050.1730.7920.7591.522
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromIssuanceOfDebt dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:DebtInstrument, us-gaap:SubsequentEventType

us-gaap:ProceedsFromIssuanceOfDebt

bkh:BlackHillsCorporation, us-gaap:CorporateNonSegment, bkh:CorporateTermLoanDueNovember2021, us-gaap:SubsequentEvent


Proceeds
Period End2021-02-24
Value800
Percentage of ProceedsFromIssuanceOfDebt100.0

us-gaap:ProceedsFromOtherShortTermDebt

us-gaap:ProceedsFromOtherShortTermDebt


Proceeds
Period End2021-06-302021-03-31
Value0.0800
Percentage of ProceedsFromOtherShortTermDebt0.0100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1.031-0.74-0.542-0.045-5.083-1.391-14.745-0.044-0.291-1.657-0.803-8.93-0.127-1.4-0.2-0.06-0.104-6.555-6.675-16.492.614-2.409-1.759-5.062-0.562-1.921-0.44-1.322-2.451-15.3940.00.00.00.0-5.6665.591-2.758-1.481-0.012-0.159-0.014-0.776-1.696-7.465-0.463
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForDoubtfulAccounts

us-gaap:ProvisionForDoubtfulAccounts


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-30
Value-367000.01877000.0456000.01756000.03196000.03519000.0158000.0724000.0
Percentage of ProvisionForDoubtfulAccounts100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForDoubtfulAccounts us-gaap:AccountsNotesLoansAndFinancingReceivableByReceivableType

us-gaap:TradeAccountsReceivable


Provision
Period End2020-12-312020-09-302020-06-30
Value-400000.01700000.01500000.0
Percentage of ProvisionForDoubtfulAccounts-87.796.846.9

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewApprovedByRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC


Public
Period End2021-03-01
Value6.5
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount100.0

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC


Public
Period End2021-03-01
Value6.5
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount100.0

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType

bkh:BlackHillsEnergyNebraskaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:NebraskaPublcServiceCommissionNPSC, us-gaap:SubsequentEvent


Public
Period End2021-01-26
Value6.5
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount0.0

us-gaap:PublicUtilitiesRequestedRateIncreaseDecreaseAmount dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency

us-gaap:PublicUtilitiesRequestedRateIncreaseDecreaseAmount

bkh:BlackHillsEnergyColoradoGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:ColoradoPublicUtilitiesCommissionCPUC


Public
Period End2021-06-012020-09-112019-02-01
Value14132.5
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount100.0100.0100.0

bkh:BlackHillsEnergyIowaGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:IowaUtilitiesBoardIUB


Public
Period End2021-06-01
Value8.3
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount56.8

bkh:BlackHillsEnergyKansasGas, bkh:RateReviewFiledwiththeRegulatoryAgency, bkh:KansasCorporationCommissionKCC


Public
Period End2021-05-07
Value5.3
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount0.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax us-gaap:DerivativeInstrumentRisk, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

us-gaap:CommodityContract, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-42000.023000.0-57000.0138000.053000.0371000.04000.0124000.0-64000.0-426000.0-516000.021000.0118000.0476000.074000.0-166000.0-243000.0-181000.0-1157000.0-1469000.0-2011000.0-2301000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InterestRateSwap, us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value563000.0523000.0934000.0543000.0544000.0543000.0546000.0548000.0541000.0550000.0570000.0560000.0561000.0561000.0463000.0464000.0522000.0463000.0890000.0546000.02209000.0-1111000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax-1340.52273.9-1638.6393.51026.4146.413650.0441.9-845.3-129.1-110.52666.7475.4117.9625.7-279.5-214.8-255.8-76.9-37.2-109.848.3

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:StatementEquityComponents

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value422000.0365000.044000.0430000.0396000.0479000.0839000.0-25000.0154000.0153000.0414000.0449000.0452000.0451000.0241000.0237000.0237000.0229000.0366000.0287000.0285000.0286000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax-1004.81587.0-77.2311.6747.2129.120975.0-20.2-240.6-35.9-80.22138.1383.194.7325.7-142.8-97.5-126.5-31.6-19.5-14.2-12.4

us-gaap:ReclassificationOutOfAccumulatedOtherComprehensiveIncome, us-gaap:AccumulatedOtherComprehensiveIncome


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value943000.0911000.0921000.01111000.0993000.01393000.01389000.0647000.0631000.0277000.0468000.01030000.01131000.01488000.0778000.0535000.0516000.0511000.099000.0-636000.0483000.0-3126000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax-2245.23960.9-1615.8805.11873.6375.534725.0521.8-985.9-65.0-90.74904.8958.5312.61051.4-322.3-212.3-282.3-8.643.3-24.0135.9

us-gaap:RepaymentsOfOtherShortTermDebt

us-gaap:RepaymentsOfOtherShortTermDebt


Repayments
Period End2021-06-302021-03-31
Value0.0200
Percentage of RepaymentsOfOtherShortTermDebt0.0100.0

us-gaap:RepaymentsOfOtherShortTermDebt us-gaap:DebtInstrument, us-gaap:ShortTermDebtType

bkh:SeniorUnsecuredNotesDue2021, us-gaap:LineOfCredit


Repayments
Period End2021-06-302021-03-31
Value0.0200
Percentage of RepaymentsOfOtherShortTermDebt0.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value3295000.01310000.01637000.01827000.0674000.01677000.03890000.0538000.02319000.01677000.02439000.0755000.01714000.01720000.01741000.02392000.01657000.01630000.01631000.0561000.01242000.01397000.01392000.0209000.0
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value3698000.01672000.01468000.01781000.02263000.01769000.03948000.0-589000.02107000.03019000.01433000.0
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation112.2127.689.797.5335.8105.5101.5-109.5125.6123.8189.8

us-gaap:CommonStock


Stock
Period End2021-06-302021-03-312020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value21000.083000.069000.0054000.049000.0013000.065000.0
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation0.66.310.20.01.49.10.00.58.6

us-gaap:TreasuryStock


Stock
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-31
Value-424000.0-445000.0169000.046000.0-1658000.0-92000.0-112000.01078000.0-430000.0-593000.0-743000.0
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation-12.9-34.010.32.5-246.0-5.5-2.9200.4-25.6-24.3-98.4

us-gaap:StockholdersEquityOther

us-gaap:StockholdersEquityOther


Stockholders
Period End2021-06-302021-03-312018-12-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value-1000.02000.065000.0-151000.06000.0-2000.0173000.04000.03000.0-500000.04000.07000.013000.09000.0016000.00
Percentage of StockholdersEquityOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0

us-gaap:StockholdersEquityOther us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312018-09-302018-06-302018-03-31
Value-1000.02000.08000.01000.016000.0
Percentage of StockholdersEquityOther100.0100.0-5.316.7-800.0

us-gaap:TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit dei:LegalEntity, us-gaap:RegulatoryAgency

us-gaap:TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit

bkh:BlackHillsEnergyNebraskaGas, bkh:NebraskaPublicServiceCommissionNPSC


Tax
Period End2021-01-26
Value2900000.0
Percentage of TaxCutsAndJobsActOf2017IncomeTaxExpenseBenefit100.0

us-gaap:TaxesExcludingIncomeAndExciseTaxes

us-gaap:TaxesExcludingIncomeAndExciseTaxes


Taxes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value1515141314141312131312111313101313131112121210101111111111109.4951010109.286109.478119.29.057.2428.2187.467.4266.2396.477
Percentage of TaxesExcludingIncomeAndExciseTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:AmountOfPayrollTaxSocialSecurityEmploymentTaxDeferralAllowedUnderTheCARESAct

bkh:AmountOfPayrollTaxSocialSecurityEmploymentTaxDeferralAllowedUnderTheCARESAct


Amount
Period End2020-09-302020-06-30
Value4000000.02900000.0
Percentage of AmountOfPayrollTaxSocialSecurityEmploymentTaxDeferralAllowedUnderTheCARESAct100.0100.0

bkh:AtTheMarketEquityOfferingProgramAuthorizedAggregateValue

bkh:AtTheMarketEquityOfferingProgramAuthorizedAggregateValue


At
Period End2020-08-032020-06-302018-09-302017-08-042017-06-302016-06-302016-03-18
Value400300300300200200200
Percentage of AtTheMarketEquityOfferingProgramAuthorizedAggregateValue100.0100.0100.0100.0100.0100.0100.0

bkh:AtTheMarketEquityOfferingProgramAuthorizedAggregateValue us-gaap:SubsequentEventType

us-gaap:SubsequentEvent


At
Period End2020-08-032017-08-04
Value400300
Percentage of AtTheMarketEquityOfferingProgramAuthorizedAggregateValue100.0100.0

bkh:CustomerDepositsandPrepayments

bkh:CustomerDepositsandPrepayments


Customer
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-03-312017-12-31
Value47505259454354564039433544
Percentage of CustomerDepositsandPrepayments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:DeferredTaxLiabilityState

bkh:DeferredTaxLiabilityState


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value7372645847353730191411
Percentage of DeferredTaxLiabilityState100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType

bkh:DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets

us-gaap:HedgeFundsMultistrategy, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1719182329
Percentage of DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets100.0100.0100.0100.0100.0

us-gaap:RealEstateFunds, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1414131515
Percentage of DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets81.972.872.166.553.1

bkh:DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType

us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3133323944
Percentage of DefinedBenefitPlanAlternativeInvestmentsFairValueOfPlanAssets181.9172.8172.1166.5153.1

bkh:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicBenefitCostExpectedRateofReturnOnAssetsForNextFiscalYear us-gaap:RetirementPlanType

bkh:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicBenefitCostExpectedRateofReturnOnAssetsForNextFiscalYear

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-31
Value4.5
Percentage of DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicBenefitCostExpectedRateofReturnOnAssetsForNextFiscalYear100.0

bkh:DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType

bkh:DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments

bkh:CommonCollectiveTrustCashAndCashEquivalents, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value167.0549.9232.1845.307
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments100.0100.0100.0100.0100.0

bkh:CommonCollectiveTrustEquityFund, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1008767109101
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments596.71234.8679.85013.61903.5

bkh:CommonCollectiveTrustFixedIncomeFund, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value324306279262209
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments1932.54341.92813.112011.43953.6

us-gaap:CashAndCashEquivalents, us-gaap:FairValueMeasurementsRecurring, us-gaap:DefinedBenefitPostretirementHealthCoverage


Defined
Period End2020-12-312019-12-31
Value8.1658.305
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments48.6117.7

bkh:DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType

us-gaap:FairValueMeasurementsRecurring, us-gaap:DefinedBenefitPostretirementHealthCoverage


Defined
Period End2020-12-312019-12-31
Value8.1658.305
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments48.6117.7

us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value441400358377319
Percentage of DefinedBenefitPlanFairValueofPlanAssetsExcludingNetAssetValueinvestments2629.25677.63612.417262.76026.3

bkh:EmployeeServiceShareBasedCompensationOtherThanOptionsTotalPayoutValue us-gaap:AwardType

bkh:EmployeeServiceShareBasedCompensationOtherThanOptionsTotalPayoutValue

us-gaap:PerformanceShares


Employee
Period End2020-12-31
Value3300000.0
Percentage of EmployeeServiceShareBasedCompensationOtherThanOptionsTotalPayoutValue100.0

bkh:LeaseLiability

bkh:LeaseLiability


Lease
Period End2020-12-312019-12-31
Value4543000.05000000.0
Percentage of LeaseLiability100.0100.0

bkh:LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts

bkh:LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value356131702977313332381866
Percentage of LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts100.0100.0100.0100.0100.0100.0

bkh:LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts dei:LegalEntity, us-gaap:ConsolidationItems

bkh:BlackHillsCorporation, us-gaap:CorporateNonSegment


Long
Period End2020-12-312019-12-312018-12-312017-12-31
Value3019262524322588
Percentage of LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts84.882.881.782.6

bkh:LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts dei:LegalEntity, us-gaap:StatementBusinessSegments

bkh:SouthDakotaElectric, bkh:ElectricUtilities


Long
Period End2020-12-312019-12-312018-12-31
Value339342342
Percentage of LongTermDebtBeforeTheDeductionOfDeferredFinancingCosts9.510.811.5

bkh:NumberOfMegawattsCapacityPurchased bkh:FuelType, dei:LegalEntity, us-gaap:LongTermContractForPurchaseOfElectricPower

bkh:NumberOfMegawattsCapacityPurchased

bkh:Solar, bkh:ColoradoElectric, bkh:TCColoradoSolarLLC


Number
Period End2021-02-19
Value200.0
Percentage of NumberOfMegawattsCapacityPurchased100.0

bkh:NumberOfMegawattsCapacityPurchased bkh:FuelType, us-gaap:LongTermContractForPurchaseOfElectricPower

bkh:Coal, bkh:ColoradoElectric


Number
Period End2020-12-31
Value25.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:Coal, bkh:SouthDakotaElectric


Number
Period End2020-12-31
Value50.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:Solar, bkh:SouthDakotaElectric


Number
Period End2020-12-31
Value80.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:Wind, bkh:ColoradoElectric


Number
Period End2020-12-31
Value60.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:Wind, bkh:SouthDakotaElectric


Number
Period End2020-12-31
Value12.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:Wind, bkh:WyomingElectric


Number
Period End2020-12-31
Value30.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:NumberOfMegawattsCapacityPurchased dei:LegalEntity, us-gaap:LongTermContractForPurchaseOfElectricPower

bkh:ColoradoElectric, bkh:CityOfColoradoSprings


Number
Period End2020-07-01
Value60.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:SouthDakotaElectric, bkh:FallRiverSolar


Number
Period End2020-09-11
Value80.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:NumberOfMegawattsCapacityPurchased dei:LegalEntity, us-gaap:RegulatoryAgency

bkh:BlackHillsWyomingandWyomingElectric, bkh:FederalEnergyRegulatoryCommissionFERC


Number
Period End2020-10-15
Value60.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:NumberOfMegawattsCapacityPurchased dei:LegalEntity, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType

bkh:BlackHillsWyomingandWyomingElectric, bkh:FederalEnergyRegulatoryCommissionFERC, us-gaap:SubsequentEvent


Number
Period End2020-10-15
Value60.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:NumberOfMegawattsCapacityPurchased us-gaap:LongTermContractForPurchaseOfElectricPower

bkh:SouthDakotaElectric


Number
Period End2020-12-31
Value50.0
Percentage of NumberOfMegawattsCapacityPurchased0.0

bkh:NumberofMegawattsSoldUnderLongTermContract dei:LegalEntity, us-gaap:RegulatoryAgency

bkh:NumberofMegawattsSoldUnderLongTermContract

bkh:BlackHillsWyomingandWyomingElectric, bkh:FederalEnergyRegulatoryCommissionFERC


Numberof
Period End2020-10-15
Value60.0
Percentage of NumberofMegawattsSoldUnderLongTermContract100.0

bkh:NumberofMegawattsSoldUnderLongTermContract us-gaap:RelatedPartyTransaction

bkh:BlackHillsWyomingandWyomingElectric


Numberof
Period End2020-12-31
Value60.0
Percentage of NumberofMegawattsSoldUnderLongTermContract0.0

bkh:OperatingLossCarryforwardsWithNoExpirationDate us-gaap:IncomeTaxAuthority

bkh:OperatingLossCarryforwardsWithNoExpirationDate

us-gaap:InternalRevenueServiceIRS


Operating
Period End2020-12-31
Value79
Percentage of OperatingLossCarryforwardsWithNoExpirationDate100.0

bkh:PercentageOfMonthlyRedemption us-gaap:Range, us-gaap:DefinedBenefitPlanByPlanAssetCategories

bkh:PercentageOfMonthlyRedemption

srt:Minimum, us-gaap:HedgeFundsMultistrategy


Percentage
Period End2020-12-31
Value10.0
Percentage of PercentageOfMonthlyRedemption100.0

bkh:PropertyPlantEquipmentExcludingConstructionInProgress us-gaap:ConsolidationItems

bkh:PropertyPlantEquipmentExcludingConstructionInProgress

us-gaap:CorporateNonSegment


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value5.6925.7215.7215.585.4460.3765.5245.4980.368
Percentage of PropertyPlantEquipmentExcludingConstructionInProgress100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:PropertyPlantEquipmentExcludingConstructionInProgress us-gaap:StatementBusinessSegments

bkh:Mining


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-31
Value186179175158151154
Percentage of PropertyPlantEquipmentExcludingConstructionInProgress3277.43132.33070.32838.22785.741125.0

bkh:PowerGeneration


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value529532173155161156153143139135134
Percentage of PropertyPlantEquipmentExcludingConstructionInProgress9310.09306.03041.42788.02964.241681.12783.82601.437879.30.00.0

bkh:PublicUtilitiesDevelopmentCostsExpensed dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency

bkh:PublicUtilitiesDevelopmentCostsExpensed

bkh:SouthDakotaElectric, bkh:ApplicationforDeferredAccountingTreatmentWithdrawn, bkh:SouthDakotaPublicUtilitiesCommissionSDPUC


Public
Period End2020-12-31
Value5400000.0
Percentage of PublicUtilitiesDevelopmentCostsExpensed100.0

bkh:PublicUtilitiesPropertyPlantandEquipmentExcludingConstructioninProgress us-gaap:StatementBusinessSegments

bkh:PublicUtilitiesPropertyPlantandEquipmentExcludingConstructioninProgress

bkh:ElectricUtilities


Public
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value315929563049297628012670254722602228
Percentage of PublicUtilitiesPropertyPlantandEquipmentExcludingConstructioninProgress100.0100.0100.0100.0100.0100.0100.0100.0100.0

bkh:GasUtilities


Public
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value32452918246822062070732671618561
Percentage of PublicUtilitiesPropertyPlantandEquipmentExcludingConstructioninProgress102.798.780.974.173.927.426.427.325.2

bkh:SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers dei:LegalEntity, us-gaap:RegulatoryAgency

bkh:SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers

bkh:BlackHillsEnergyColoradoElectric, bkh:ColoradoPublicUtilitiesCommissionCPUC


Settlement
Period End2020-12-30
Value9300000.0
Percentage of SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers100.0

bkh:BlackHillsEnergyNebraskaGas, bkh:NebraskaPublicServiceCommissionNPSC


Settlement
Period End2021-01-26
Value2900000.0
Percentage of SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers0.0

bkh:SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers dei:LegalEntity, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType

bkh:BlackHillsEnergyNebraskaGas, bkh:NebraskaPublicServiceCommissionNPSC, us-gaap:SubsequentEvent


Settlement
Period End2021-01-26
Value2900000.0
Percentage of SettlementOfPlanToProvideTCJARelatedCustomerBillingCreditsToItsCustomers0.0

bkh:SharebasedCompensationArrangementbySharebasedPaymentAwardPayoutPercentageofTarget us-gaap:AwardType

bkh:SharebasedCompensationArrangementbySharebasedPaymentAwardPayoutPercentageofTarget

us-gaap:PerformanceShares


Sharebased
Period End2020-12-312019-12-312018-12-312014-12-312013-12-31
Value112.350.58861.6192.01.75
Percentage of SharebasedCompensationArrangementbySharebasedPaymentAwardPayoutPercentageofTarget100.0100.0100.0100.0100.0

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFiveYears bkh:NaturalGasIndices

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFiveYears

bkh:ONEOKOklahoma


Unrecorded
Period End2020-12-31
Value4560000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinFiveYears100.0

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFourYears bkh:NaturalGasIndices

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinFourYears

bkh:NNGVentura


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1820000.001810000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinFourYears100.00.0100.0

bkh:NorthwestWyomingPool


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value910000.01510000.00
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinFourYears50.00.00.0

bkh:ONEOKOklahoma


Unrecorded
Period End2020-12-31
Value5490000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinFourYears301.6

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears bkh:NaturalGasIndices

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears

bkh:NNGVentura


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1840000.01810000.03650000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears100.0100.0100.0

bkh:NorthwestWyomingPool


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1510000.01510000.00
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears82.183.40.0

bkh:ONEOKOklahoma


Unrecorded
Period End2020-12-31
Value5475000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinThreeYears297.6

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears bkh:NaturalGasIndices

bkh:UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears

bkh:NNGVentura


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1810000.03650000.03660000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears100.0100.0100.0

bkh:NorthwestWyomingPool


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1510000.01510000.00
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears83.441.40.0

bkh:ONEOKOklahoma


Unrecorded
Period End2020-12-31
Value5475000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueWithinTwoYears302.5

bkh:UnrecordedUnconditionalPurchaseObligationDueintheNextTwelveMonths bkh:NaturalGasIndices

bkh:UnrecordedUnconditionalPurchaseObligationDueintheNextTwelveMonths

bkh:NNGVentura


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value3650000.03660000.03650000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueintheNextTwelveMonths100.0100.0100.0

bkh:NorthwestWyomingPool


Unrecorded
Period End2020-12-312019-12-312018-12-31
Value1510000.01520000.0720000.0
Percentage of UnrecordedUnconditionalPurchaseObligationDueintheNextTwelveMonths41.441.519.7

bkh:ONEOKOklahoma