NI


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

Table of contents



us-gaap:CommonStockValue

us-gaap:CommonStockParOrStatedValuePerShare

us-gaap:PreferredStockParOrStatedValuePerShare
us-gaap:StatementClassOfStock
us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType

us-gaap:SharesIssued
us-gaap:StatementEquityComponents

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization

us-gaap:GainsLossesOnExtinguishmentOfDebt
us-gaap:DebtInstrument

us-gaap:GrossProfit

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic

us-gaap:IncomeTaxExpenseBenefit

us-gaap:InterestExpense

us-gaap:InterestIncomeExpenseNonoperatingNet

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted

us-gaap:NonoperatingIncomeExpense

us-gaap:OperatingCostsAndExpenses

us-gaap:OperatingIncomeLoss
us-gaap:StatementBusinessSegments

us-gaap:OtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherNonoperatingIncomeExpense

us-gaap:PreferredStockDividendsIncomeStatementImpact

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents

us-gaap:RegulatedOperatingRevenue
us-gaap:StatementBusinessSegments

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

us-gaap:Revenues
us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments, us-gaap:Subsegments
us-gaap:Subsegments

us-gaap:Assets
dei:LegalEntity
us-gaap:StatementBusinessSegments
dei:LegalEntity
us-gaap:Liabilities

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:StockholdersEquity
us-gaap:StatementClassOfStock, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent
dei:LegalEntity

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:AccountsReceivableNetCurrent

us-gaap:InventoryRawMaterialsAndSupplies

us-gaap:OtherAssetsCurrent

us-gaap:PropertyPlantAndEquipmentGross
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
us-gaap:PropertyPlantAndEquipmentByType

us-gaap:PropertyPlantAndEquipmentNet
dei:LegalEntity

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

us-gaap:Goodwill
us-gaap:StatementBusinessSegments

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent

us-gaap:AccountsPayableCurrent

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:DividendsPayableCurrent

us-gaap:LiabilitiesCurrent
dei:LegalEntity

us-gaap:OperatingLeaseLiabilityCurrent
nix:LeaseType

us-gaap:OtherLiabilitiesCurrent

us-gaap:TaxesPayableCurrent

us-gaap:LiabilitiesNoncurrent

us-gaap:LongTermDebtAndCapitalLeaseObligations

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
us-gaap:RetirementPlanType

us-gaap:MinorityInterest

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent
nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo
nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree
nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour
nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive
nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive
nix:LeaseType
nix:LeaseType
us-gaap:OperatingLeaseLiability

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue
nix:LeaseType
nix:LeaseType
us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
us-gaap:StatementClassOfStock, us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
us-gaap:StatementEquityComponents

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax
us-gaap:StatementEquityComponents

us-gaap:TreasuryStockValue

us-gaap:MinorityInterest

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:DepreciationDepletionAndAmortization

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetIncomeLoss

us-gaap:ProfitLoss
us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:DeferredTaxLiabilities

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance
us-gaap:StatementEquityComponents
nix:ATMProgramEquityRemainingAvailableforIssuance
dei:LegalEntity
nix:BusinessesImpactedbyIncident
dei:LegalEntity
nix:CashContribution

nix:CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions

nix:CharitableContributions

nix:CoalfiredGeneratingCapacityPercentofTotalCapacity

nix:CoalfiredGeneratingCapacityPercentofTotalCoalFiredCapacity

nix:CostsResultingfromtheGreaterLawrenceIncident

nix:DebtInstrumentTendered
us-gaap:RetirementPlanType
nix:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicCostDiscountRateForInterestCost
us-gaap:RetirementPlanType
nix:DefinedBenefitPlanPensionAssetIncreaseDecreaseForRemeasurementDueToSettlement

nix:ExpensesOtherThanThirdPartyClaims
dei:LegalEntity, us-gaap:Range

nix:ExpensesRelatedtoThirdPartyClaims
dei:LegalEntity, us-gaap:Range
us-gaap:StatementEquityComponents
nix:ForwardContractIndexedToIssuersEquityForwardRatePerShareAtFairValue
dei:LegalEntity
nix:FutureCashContribution
dei:LegalEntity
nix:GasMetersAffected

nix:GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense

nix:ImpairmentAndGainLossOnSaleOfAssetsNet

nix:IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets

nix:IncreaseDecreaseinCustomerAccountsReceivableBilledLessReserve

nix:IncreaseDecreaseinCustomerAccountsReceivableUnbilledLessReserve

nix:IncreaseDecreaseinEffectiveTaxRate

nix:IncrementalCommonSharesAttributableToDilutiveEffectOfEquityUnitPurchaseAgreementsIfConverted

nix:MiscellaneousNonOperatingIncomeExpense

nix:PaymentToRenewableGenerationAssetDeveloper
dei:LegalEntity, us-gaap:Range
nix:PenaltyPerViolationofEmergencyResponsePlan
dei:LegalEntity, us-gaap:Range
nix:PenaltyforViolationsofEmergencyResponsePlan

nix:PensionandOtherPostretirementNonServiceCost
dei:LegalEntity
nix:PipelineReplacementExpenses
dei:LegalEntity
nix:PleaAgreementCriminalFine

nix:ProceedsFromInsuranceSettlement

nix:SaleOfEmissionReductionCredits

nix:SecuritizationTransactionFees
us-gaap:FinancialInstrument

nix:ServiceAreaByCounty

nix:StockIssuedDuringThePeriodEquityUnitsValue
us-gaap:StatementEquityComponents
us-gaap:StatementEquityComponents
nix:StockIssuedDuringThePeriodSharesEquityUnits

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CommonStockDividendsPerShareDeclared

us-gaap:DeferredIncomeTaxesAndTaxCredits
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement
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:DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost

us-gaap:DilutiveSecuritiesEffectOnBasicEarningsPerShareOther
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss

us-gaap:DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown

us-gaap:DividendsCommonStockCash
us-gaap:StatementEquityComponents

us-gaap:DividendsPreferredStockCash
us-gaap:StatementEquityComponents

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate

us-gaap:FinancingReceivableAllowanceForCreditLossesRecovery
us-gaap:StatementBusinessSegments

us-gaap:FinancingReceivableAllowanceForCreditLossesWriteOffs
us-gaap:StatementBusinessSegments
us-gaap:StatementEquityComponents
us-gaap:ForwardContractIndexedToIssuersEquityForwardRate
us-gaap:StatementEquityComponents
us-gaap:ForwardContractIndexedToIssuersEquityShares

us-gaap:GainLossOnSaleOfBusiness
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:GainLossOnSalesOfAssetsAndAssetImpairmentCharges

us-gaap:IncreaseDecreaseInAssetRetirementObligations

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInRegulatoryAssetsAndLiabilities

us-gaap:IncrementalCommonSharesAttributableToContingentlyIssuableShares

us-gaap:IncrementalCommonSharesAttributableToEquityForwardAgreements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:InsuranceRecoveries

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent
us-gaap:StatementEquityComponents

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax

us-gaap:OtherOperatingActivitiesCashFlowStatement

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForRemovalCosts

us-gaap:PaymentsForRestructuring

us-gaap:PaymentsOfDividendsPreferredStockAndPreferenceStock

us-gaap:PaymentsOfStockIssuanceCosts
nix:EquityUnitsComponents

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt
us-gaap:StatementClassOfStock
us-gaap:PreferredStockAmountOfPreferredDividendsInArrears
us-gaap:StatementClassOfStock
us-gaap:PreferredStockDividendsPerShareDeclared
us-gaap:StatementClassOfStock
us-gaap:PreferredStockPerShareAmountsOfPreferredDividendsInArrears
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:ProceedsFromDebtNetOfIssuanceCosts

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromMinorityShareholders

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths

us-gaap:ProvisionForLoanLeaseAndOtherLosses
us-gaap:StatementBusinessSegments

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding
us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:SubsequentEventType
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding
us-gaap:PublicUtilitiesRequestedRateIncreaseDecreaseAmount
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:SubsequentEventType

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
us-gaap:StatementEquityComponents

us-gaap:RegulatedOperatingRevenueOther
us-gaap:StatementBusinessSegments

us-gaap:RepaymentsOfLongTermDebtAndCapitalSecurities

us-gaap:RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths

us-gaap:RestructuringReservePeriodIncreaseDecrease

us-gaap:StockIssuedDuringPeriodSharesEmployeeBenefitPlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans
us-gaap:StatementEquityComponents
us-gaap:CapitalUnitsByClass
us-gaap:StockIssuedDuringPeriodSharesNewIssues
us-gaap:CapitalUnitsByClass, us-gaap:SubsequentEventType

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueEmployeeBenefitPlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueOther
us-gaap:StatementEquityComponents

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation
us-gaap:StatementEquityComponents

us-gaap:TaxesExcludingIncomeAndExciseTaxes

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations

dei:EntityCommonStockSharesOutstanding

nix:AcceleratedDepreciationAndOtherPropertyDifferences

nix:AccruedInsuranceClaimsCurrent

nix:AdditionalObligationToTheDeveloper
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
nix:AssetsHeldforSaleTotalCurrentAssets
dei:LegalEntity
nix:COVID19RelatedCostsRegulatoryAsset
us-gaap:RetirementPlanType
nix:ChangeInAccumulatedOtherComprehensiveIncomeDueToInterimMeasurement
us-gaap:RetirementPlanType
nix:ChangeInRegulatoryAssetsDueToInterimMeasurement
us-gaap:RetirementPlanType
nix:ChangeToDefinedBenefitPlanNetPeriodicCostsDueToInterimMeasurement

nix:CoalfiredGeneratingCapacity

nix:ColumbiaOfMarylandCOVIDReliefFunds

nix:CommonDividendsPayableCurrent
us-gaap:StatementEquityComponents
nix:CommonStockAggregateSalePrice

nix:CustomerAccountsReceivableBilledLessReserve

nix:CustomerAccountsReceivableUnbilledLessReserve

nix:DeferredChargesAndOther

nix:DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities

nix:DeferredPayrollTaxes

nix:DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental
us-gaap:RetirementPlanType
nix:DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeOrRegulatoryAssetOrLiability
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType
nix:DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanType
nix:DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
nix:Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilities
us-gaap:StatementClassOfStock
nix:DepositaryStockLiquidationPreference

nix:EnergyCommodityContractsFutureMinimumPaymentsDue

nix:EnergyCommodityContractsFutureMinimumPaymentsDueNextTwelveMonths

nix:ExchangeGasPayable

nix:ExchangeGasReceivable

nix:ExpectedFutureObligationToTheDeveloper

nix:FinanceLeasesFutureMinimumPaymentsInterestIncludedinPayments

nix:FutureRFPCapacity

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDue

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueNextTwelveMonths

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueThereafter

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFiveYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFourYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinThreeYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinTwoYears

nix:LegalAndEnvironmentalReserves
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
nix:LiabilitiesHeldforSaleLongTermDebt
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
nix:LiabilitiesHeldforSaleTotalCurrentLiabilities
us-gaap:LossContingenciesByNatureOfContingency
nix:LiabilityForEstimatedRemediationCosts

nix:LongtermDebtFutureMinimumPaymentsDue

nix:LongtermDebtFutureMinimumPaymentsDueThereafter

nix:LongtermDebtFutureMinimumPaymentsDueinFiveYears

nix:LongtermDebtFutureMinimumPaymentsDueinTwoYears

nix:LongtermLeaseLiability
nix:ConstructionCompletion, nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType
nix:NameplateCapacity
nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType

nix:NetAssetValueExcludedFromFairValueByInput
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FinancialInstrument

nix:NetProceedsFromSale
us-gaap:CapitalUnitsByClass
us-gaap:CapitalUnitsByClass, us-gaap:SubsequentEventType
us-gaap:SubsequentEventType
us-gaap:LossContingenciesByNatureOfContingency
nix:NumberOfWasteDisposalSitesIdentifiedByProgram
us-gaap:LossContingenciesByNatureOfContingency, us-gaap:SubsequentEventType

nix:ObligationToTheDeveloper

nix:OperatingLeasesFutureMinimumPayamentsInterestIncludedinPayments

nix:OtherLiabilitiesFutureMinimumPaymentsDue

nix:OtherLiabilitiesFutureMinimumPaymentsDueNextTwelveMonths

nix:OtherLiabilitiesFutureMinimumPaymentsDueinThreeYears

nix:OtherLiabilitiesFutureMinimumPaymentsDueinTwoYears

nix:OtherRegulatoryAssets

nix:PlantAndEquipmentAssociatedWithSchahferGeneratingStationRetirement

nix:PreferredDividendsPayableCurrent

nix:PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyAtCostLessAccumulatedDepreciation

nix:PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceNet

nix:PurchaseContractLiability
us-gaap:LossContingenciesByNatureOfContingency
nix:ReasonablyPossibleRemediationCostsVarianceFromReserve
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding
nix:RegulatoryNetCapitalExpendituresIncludedInFiling
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:SubsequentEventType
us-gaap:FinancialInstrument
nix:SeasonalLimit

nix:SecurityInterestAndOtherSubsetOfAsset

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDue

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFiveYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFourYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinThreeYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinTwoYears

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue
us-gaap:SubsequentEventType

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue
us-gaap:SubsequentEventType

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueThereafter

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFiveYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFourYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinThreeYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinTwoYears

nix:ShorttermLeaseLiability
nix:PurchaseAndServiceObligations
nix:StorageCapacity
nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType

nix:TotalExpectedContributions

nix:TotalFutureContractualObligationsDue

nix:TotalFutureContractualObligationsDueNextTwelveMonths

nix:TotalFutureContractualObligationsDueThereafter

nix:TotalFutureContractualObligationsDueinFiveYears

nix:TotalFutureContractualObligationsDueinFourYears

nix:TotalFutureContractualObligationsDueinThreeYears

nix:TotalFutureContractualObligationsDueinTwoYears

nix:TotalFutureMinimumLeasePaymentsDue

nix:TotalFutureMinimumLeasePaymentsDueNextTwelveMonths

nix:TotalFutureMinimumLeasePaymentsDueThereafter

nix:TotalFutureMinimumLeasePaymentsDueinFiveYears

nix:TotalFutureMinimumLeasePaymentsDueinFourYears

nix:TotalFutureMinimumLeasePaymentsDueinThreeYears

nix:TotalFutureMinimumLeasePaymentsDueinTwoYears

nix:TotalLeaseLiability

nix:Totalleasedassets

nix:TradeReceivablesAvailableForTransfer

nix:TradeReceivablesNotTransferred

nix:TradeReceivablesTransferredNet

nix:UndiscountedExcessAmount

nix:VIENetAssets

nix:WindPowerPurchaseAgreementCapacity

nix:WindPowerPurchaseAgreementPurchasePercentage

nix:WorkingCapitalAdjustment

us-gaap:AccountsReceivableGrossCurrent

us-gaap:AccrualForEnvironmentalLossContingencies

us-gaap:AccruedInsuranceNoncurrent

us-gaap:AccumulatedDeferredInvestmentTaxCredit

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent

us-gaap:AssetRetirementObligation

us-gaap:AssetRetirementObligationsNoncurrent
dei:LegalEntity

us-gaap:AssetsFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleDebtSecuritiesAmortizedCostBasis
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecurities
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
us-gaap:FinancialInstrument
us-gaap:AvailableForSaleSecuritiesDebtMaturitiesWithinOneYearFairValue

us-gaap:AvailableForSaleSecuritiesDebtSecurities
us-gaap:FinancialInstrument

us-gaap:AvailableForSaleSecuritiesDebtSecuritiesNoncurrent

us-gaap:CapitalLeaseObligations
dei:LegalEntity, us-gaap:LongtermDebtType

us-gaap:CapitalizationLongtermDebtAndEquity

us-gaap:CapitalizedComputerSoftwareGross

us-gaap:CommercialPaper

us-gaap:DebtInstrumentCarryingAmount
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentFaceAmount
us-gaap:DebtInstrument
us-gaap:DebtInstrumentRepurchasedFaceAmount

us-gaap:DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet

us-gaap:DebtSecuritiesAvailableForSaleAllowanceForCreditLoss
us-gaap:FinancialInstrument

us-gaap:DebtSecuritiesAvailableForSaleUnrealizedLossPosition

us-gaap:DeferredCostsCurrent

us-gaap:DeferredIncomeTaxLiabilities

us-gaap:DeferredTaxAssetsCharitableContributionCarryforwards

us-gaap:DeferredTaxAssetsGross

us-gaap:DeferredTaxAssetsOperatingLossCarryforwards
us-gaap:IncomeTaxAuthority

us-gaap:DeferredTaxAssetsOther

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsPostretirementBenefits

us-gaap:DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsAccruedLiabilities
us-gaap:RetirementPlanFundingStatus, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetGainsLossesBeforeTax
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedOtherComprehensiveIncomeNetPriorServiceCostCreditBeforeTax
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmountsRecognizedInBalanceSheet
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationDiscountRate
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingBenefitObligationRateOfCompensationIncrease
us-gaap:RetirementPlanFundingStatus, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType
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:RetirementPlanFundingStatus, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanFundedStatusOfPlan
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanHealthCareCostTrendRateAssumedNextFiscalYear
us-gaap:Range, us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanUltimateHealthCareCostTrendRate1

us-gaap:DerivativeAssets
us-gaap:BalanceSheetLocation
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:DerivativeInstrumentsAndHedgesLiabilities

us-gaap:DerivativeInstrumentsAndHedgesLiabilitiesNoncurrent

us-gaap:DerivativeLiabilities
us-gaap:BalanceSheetLocation
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeNotionalAmount
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationOtherCurrentAssets
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationOtherCurrentLiabilities
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:DisposalGroupIncludingDiscontinuedOperationPropertyPlantAndEquipmentCurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent

us-gaap:EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized

us-gaap:EnergyRelatedInventoryCoal

us-gaap:EnergyRelatedInventoryNaturalGasInStorage

us-gaap:ExcessOfReplacementOrCurrentCostsOverStatedLIFOValue
nix:LeaseType
us-gaap:FinanceLeaseLiability

us-gaap:FinanceLeaseLiabilityCurrent
nix:LeaseType

us-gaap:FinanceLeaseLiabilityNoncurrent
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDue
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree
nix:LeaseType

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo
nix:LeaseType
nix:LeaseType
us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount

us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FinanceLeaseWeightedAverageDiscountRatePercent

us-gaap:FinancialLiabilitiesFairValueDisclosure
us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FinancingReceivableAllowanceForCreditLosses
us-gaap:StatementBusinessSegments
us-gaap:StatementEquityComponents
us-gaap:ForwardContractIndexedToIssuersEquitySettlementAlternativesCashAtFairValue

us-gaap:GuarantyLiabilities
us-gaap:SubsequentEventType

us-gaap:InterestPayableCurrent

us-gaap:InvestmentsAndOtherNoncurrentAssets

us-gaap:LIFOInventoryAmount

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths
nix:LeaseType

us-gaap:LiabilitiesOfDisposalGroupIncludingDiscontinuedOperationCurrent
us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations
us-gaap:ShortTermDebtType
us-gaap:LineOfCredit
us-gaap:ShortTermDebtType
us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity

us-gaap:LongTermDebtAndCapitalLeaseObligationsCurrent

us-gaap:LongTermDebtFairValue

us-gaap:MediumTermNotes
dei:LegalEntity, us-gaap:LongtermDebtType

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent

us-gaap:OperatingLossCarryforwards

us-gaap:OtherLongTermInvestments
us-gaap:ShortTermDebtType
us-gaap:OtherShortTermBorrowings

us-gaap:PensionAndOtherPostretirementAndPostemploymentBenefitPlansLiabilitiesNoncurrent
us-gaap:RetirementPlanType
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities
us-gaap:StatementClassOfStock
us-gaap:PreferredStockLiquidationPreference
us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType
us-gaap:StatementClassOfStock
us-gaap:PreferredStockLiquidationPreferenceValue

us-gaap:PreferredStockSharesOutstanding
us-gaap:StatementClassOfStock

us-gaap:PreferredStockValueOutstanding

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentAccumulatedDepreciation

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentNet
dei:LegalEntity

us-gaap:PublicUtilitiesPropertyPlantAndEquipmentPlantInService

us-gaap:RegulatoryAssets
dei:LegalEntity, us-gaap:RegulatoryAsset
us-gaap:RegulatoryAsset

us-gaap:RegulatoryAssetsCurrent

us-gaap:RegulatoryAssetsNoncurrent

us-gaap:RegulatoryLiabilities
us-gaap:RegulatoryLiability

us-gaap:RegulatoryLiabilityCurrent

us-gaap:RegulatoryLiabilityNoncurrent

us-gaap:RemainingAmountsOfRegulatoryAssetsForWhichNoReturnOnInvestmentDuringRecoveryPeriodIsProvided

us-gaap:RestrictedCashAndCashEquivalents

us-gaap:RestructuringAndRelatedCostCostIncurredToDate1

us-gaap:RestructuringAndRelatedCostExpectedCost1

us-gaap:RestructuringReserve
us-gaap:RestructuringCostAndReserve

us-gaap:SeniorNotes
dei:LegalEntity, us-gaap:LongtermDebtType
nix:FinancialMeasurement, us-gaap:AwardDate, us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
nix:ShareBasedCompensationDirectorOptionAndIncentivePlans, us-gaap:AwardType
us-gaap:AwardDate, us-gaap:AwardType
us-gaap:AwardType
us-gaap:AwardType
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAuthorized
us-gaap:StatementEquityComponents
us-gaap:SharesIssuedPricePerShare

us-gaap:ShortTermBorrowings
us-gaap:ShortTermDebtType
us-gaap:ShortTermDebtWeightedAverageInterestRate

us-gaap:TransfersAccountedForAsSecuredBorrowingsAssociatedLiabilitiesCarryingAmount

us-gaap:UnbilledReceivablesCurrent
us-gaap:ValuationAllowancesAndReservesType
us-gaap:ValuationAllowancesAndReservesBalance

us-gaap:WeightedAverageCostInventoryAmount

Plots across concepts


IncomeStatement
Other Comprehensive Income Loss Net Of Tax
Expenses
Other Nonoperating Income Expense
Balance Sheet
Operating Lease Liability Noncurrent
Assets
Derivative Assets
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
Derivative Liabilities
Current Liabilities
Operating Lease Liability Current
Noncurrent Liabilities
Operating Lease Liability Noncurrent
Stockholders Equity
Retained Earnings Accumulated Deficit
Per Share
Earnings Per Share Diluted
CashFlow
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInOperatingActivities
Net Income Loss
NetCashProvidedByUsedInInvestingActivities
Net Cash Provided By Used In Investing Activities
NetCashProvidedByUsedInFinancingActivities
Proceeds From Issuance Of Long Term Debt
Shares
Common Stock Shares Outstanding
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 ███▇▇▇▇▇▇▇▇▇▇▅▅▅▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▃▃▃▃▂▂▁▁▁▁▁3.93.93.93.83.83.83.83.83.83.83.83.73.73.43.43.43.33.33.33.33.23.23.23.23.23.23.23.23.23.23.23.23.13.13.13.12.92.92.82.82.82.82.8NANANA
us-gaap:CommonStockParOrStatedValuePerShare ▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁1e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081e-081.0000000000000001e-071e-081e-081e-081e-081e-081e-081e-08NANANA
us-gaap:PreferredStockParOrStatedValuePerShare ▄▄▄▄▄▄▄▄▄1e-081e-081e-081e-081e-081e-081e-081e-081e-08NA1e-080.0010.001NANANANANANANANANA1e-08NANANA1e-08NANANA1e-08NANANA1e-08NANANA1e-08NANANANANANANA
us-gaap:SharesIssued ███▇▇▇▇▆▆▆▆▅▅▂▂▂▁▁▁392.329392.13391.76383.114382.917382.694382.136373.447373.249373.003372.363363.167362.915337.598337.016336.691325.757324.474323.16NANANA319.11NANANA316.037NANANA313676.0NANANA310281.0NANANA281.854NANANA278.855NANANA
us-gaap:CommonStockSharesAuthorized █████████▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁600.0600.0600.0600.0600.0600.0600.0600.0600.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0400.0NANANA
us-gaap:CommonStockSharesOutstanding ███▇▇▇▇▇▇▇▇▆▆▅▅▅▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▃▃▃▃▃▁▁▁▁▁▁▁392.328441392.129866391.760051383.11413382.917033382.694308382.13568373.446862373.249295373.002671372.363656363.167067362.915039337.598033337.015806336.691078325.756677324.474051323.159672322.56431322.004415321.360285319.110083318.474781317.668149317.281405316.037421315.597089315.215694314.800122313.675911313.135192312.420078311.814846310.280867309.597086284.767362283.890607278.855291281.111006280.472662279.930189278.855291NANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding █▁422.9393.9NA383.8383.5384.1NA374.1375.2374.7NA363.9355.2338.991NA332.396325.084325.306NA323.918322.894322.02NA321.465317.477317.39NA316.626316.101315.122NA313.813313.169312.075NA300.012295.7668293.1NA289.01287.1285.0NA279.87278.4277.5
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic █▁393.0392.7NA383.8383.5383.1NA374.1373.9373.4NA363.9354.229338.012NA331.139325.084323.681NA322.318321.725320.281NA318.09317.477316.587NA315.418315.013314.222NA312.842312.177311.12NA290.328284.3704282.9NA280.765280.2279.3NA278.088277.6276.9
us-gaap:EarningsPerShareBasic ▅▇▅▃▄▅▃▅█▇▄▁▅█▄▅▄▇▆▅▅▇▅▅▄█▇▅▆█▇▅▆█▆▅▆▇▅▅▅█▅▅▅▇0.120.720.18-0.49-0.050.16-0.41-0.020.760.55-0.05-0.950.070.82-0.160.04-0.140.650.280.080.090.560.19-0.02-0.110.850.490.10.250.850.480.160.230.840.430.060.250.680.050.120.140.730.110.120.10.71
us-gaap:EarningsPerShareDiluted ▅▇▅▃▄▅▃▅█▇▄▁▅█▄▅▄▇▆▅▅▇▅▅▄█▇▅▆█▇▅▆█▆▅▆▇▅▅▅▇▅▅▅▇0.110.720.18-0.49-0.050.16-0.41-0.020.750.55-0.05-0.950.070.81-0.160.04-0.140.650.270.080.090.560.19-0.02-0.110.850.490.10.250.850.480.160.230.830.430.060.230.660.040.120.140.720.10.120.10.71
  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 nix:ElectricOperations▄▄▂▅▁▂▃▇▄▅▄▇▄▅▄█403.7402.7370.4432.3356.4377.5393.7467.9406.6431.0403.2476.4405.1423.5420.4486.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin us-gaap:StatementBusinessSegments nix:GasDistributionOperations▂▆▄▁▂▇▅▁▂█▅▁▂▇▅▁577.31138.9826.8473.1609.31231.01006.7466.9607.11442.11061.9421.9605.11330.6951.6434.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin us-gaap:StatementBusinessSegments us-gaap:CorporateAndOther▇▇█▇▇▇▇▇▇▇█▇▇▇█▇▇▇▇▇▇▇▇▇▇▇██▇▇█▇▇▆▁▇▇▆125.6111.2139.0120.7100.9106.9126.1117.1114.4111.3171.1116.6116.3114.3143.2126.5121.9120.2118.0104.0102.3102.5112.698.3120.2130.4143.4140.0130.9128.5139.9122.0122.713.6-315.9121.7123.62.2NANANANANANANANA
  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 _ _▅▇▅▄▄▅▃▄▇▇▃▁▅▇▆▄▅▇▅▅▅▇▅▅▅█▆▅▅█▆▅▅▇▆▅▅▇▅▅▅▇▆142.2433.2218.192.891.7148.2-38.091.0463.5374.2-78.4-315.9118.4400.6270.099.6124.5416.5224.9113.7138.2381.4219.5109.7165.1530.1351.3157.8219.6533.7344.1176.4193.5428.1306.5137.2208.6399.4185.8147.5163.3399.2252.7NANANA
  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:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest ▄█▅▃▄▄▃▄▇▆▄▁▄▇▄▄▄▆▇▄▄▅▅▄▄▇▆▅▅▇8.8377.7124.7-144.64.0-62.4-101.6-42.9268.9203.3-51.4-316.122.6310.0-52.15.9-60.4216.8242.74.5-23.9111.043.9-4.6-25.5277.3145.231.279.3267.3NANANANANANANANANANANANANANANANA
us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization ▂▅▃▁▂▅▄▂▂█228.3476.8315.4143.1188.4462.4404.3196.7253.5680.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:GainsLossesOnExtinguishmentOfDebt NANA-0.1-243.4NANA0.00.00.0NA0.0-33.0-12.5NA0.00.0-111.5NA0.00.00.0NA0.00.0-97.2NA0.00.00.0NANANANANANANANANANANANANANANANANA
 us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:DebtInstrument nix:NoteRedeemedSeptember2020NANANA11.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:DebtInstrument nix:SeniorNoteRedeemedAugustSeptember2020NANANA231.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:GrossProfit NANA1211.0902.5962.71605.51397.2931.51010.41869.81461.7895.01007.01750.81368.3683.4713.91046.3856.4643.1662.7940.1761.4608.1950.41343.71130.4893.4963.41259.21049.6833.8852.41106.6943.9739.8807.61028.4890.0745.6765.81061.3925.4718.1732.01072.4
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic ▅▇▆▃▅▅▃▄█▇▃▁▅▇▆▅▄▇▆▅▅▇▆▅▄█▆▅▅█▆▅▅▇▆▅▅▇▅▅▅▇▅▅▅▇70.1359.1144.6-237.81.260.7-136.8-3.6369.1277.9-165.4-434.030.0338.8165.016.5-70.9332.5140.332.246.1291.6131.020.6-42.7426.2236.657.4118.0429.1235.777.4104.8333.6190.031.5108.2296.431.553.469.5312.757.727.843.4307.2
us-gaap:IncomeTaxExpenseBenefit ▄▅▅▃▄▄▄▄▅▅▁▂▄▅█▄▃▆▅▄▄▆▅▄▄▇▅▄▅▇▅▄▅▆▅▄▅▆▄▄▄▆▄▄▄▆13.262.656.8-64.95.9-14.92.5-10.272.259.0-153.7-94.55.562.7217.42.5-26.6121.251.58.517.4111.966.65.8-15.3150.982.325.939.5162.782.727.932.7118.263.411.537.7102.98.317.130.0107.921.9-5.615.4109.8
us-gaap:InterestExpense ▁▁▁▃▄▃▃▄▃▄▂▁▂▃▃▂▂▁▂▁▂▂▃▃█▇█▆▆▆▇▅▅▄▅▆▅▅▄▄▃▂▄▄▄▄84.584.685.695.297.092.993.395.994.195.688.183.488.793.192.487.987.785.288.085.086.090.594.394.9117.1111.0115.8109.6109.1109.1110.5103.7102.098.6103.9107.9103.2103.396.995.794.489.897.597.698.498.8
us-gaap:InterestIncomeExpenseNonoperatingNet ▁▂▃▃▄▅█▇▃▇█▄▃▅▄▄▂▂0.70.91.11.31.41.72.32.11.22.12.41.41.11.71.41.40.90.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▅█▆▃▅▆▃▅█▇▅▁▅█▄▅▄▇▆▅▅▇▅▅▄█▆▅▆█▆▅▆█▆▅▅▇▅▅▅▇▅▅▅▇60.3295.584.4-172.9-4.775.6-139.36.6296.9218.9-11.7-339.524.5276.1-52.414.0-44.4211.388.827.228.6179.759.4-4.9-36.4268.4154.231.478.2266.2151.848.171.7260.5134.019.369.4193.414.734.738.9205.231.833.228.1197.3
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest ▁▆█-3.41.03.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic ▅█▆▃▅▆▃▅█▇▅▁▅█▄▅▄46.5281.770.7-186.7-18.561.8-153.0-7.2283.1205.1-19.8-345.123.2276.1-52.414.0-44.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted 46.9NANANA-18.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NonoperatingIncomeExpense ███▁▇▇▇▇▇▇▇▇▇█▇▇▅▇▇▇▇▇▇▇▄▇▇▇▇▇▇▇▇▇▇▇▇▇▅▇▇▇▄▇▇▇-72.1-74.1-73.5-330.6-90.5-87.5-98.8-94.6-94.4-96.3-87.0-118.1-88.4-61.8-105.0-83.1-195.4-84.0-84.6-81.5-92.1-89.8-88.5-89.1-207.8-103.9-114.7-100.4-101.6-104.6-108.4-99.0-88.7-94.5-107.5-105.7-100.4-103.0-163.6-94.1-93.8-86.5-197.7-95.5-95.8-96.2
us-gaap:OperatingCostsAndExpenses ▃▅▄▃▃██▃▁█843.81112.4992.8999999999995809.7871.01457.31435.2840.5546.91495.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OperatingIncomeLoss ▅▇▅▄▄▅▃▄▇▇▃▁▅▇▆▄▅▇▅▅▅▇▅▅▅█▆▅▅█▆▅▅▇▆▅▅▇▅▅▅▇▆▅▅▇142.2433.2218.192.891.7148.2-38.091.0463.5374.2-78.4-315.9118.4400.6270.099.6124.5416.5224.9113.7138.2381.4219.5109.7165.1530.1351.3157.8219.6533.7344.1176.4193.5428.1306.5137.2208.6399.4185.8147.5163.3399.2252.7123.3139.2403.4
us-gaap:OtherComprehensiveIncomeLossNetOfTax ▃▆▅▅▅▁▅▃▄▄▃▅▄▅▄▄▄▄█▄▃▃▄▄▄▄▄▄▄▄▅▄▄▄▄▄▄▄-48.181.236.90000000000000628.38.7-138.037.7-49.5-28.0-15.6-39.723.4-1.933.90.3-8.1-16.05.5153.9-22.7-52.5-68.7-15.50.32.22.0-9.0-0.21.11.116.81.60.33.2-8.72.21.9-1.2NANANANANANANANA
 us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment▄▃▄▄▄▄▄▄▄▄▂▄▄▄▄▄▄▄▄▄▄▄▂▄▄▄▁▄▄▄█▄▄▄0.8-0.92.00.90.30.71.40.40.40.9-5.60.80.20.21.91.10.20.20.80.20.20.3-5.1-0.22.70.2-9.7-0.2-0.10.216.50.12.72.7NANANANANANANANANANANANA
 us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges▃▆▅▅▄▁▅▃▃▄▃▅▄▅▄▄▄▄█▄▃▃▄▄▄▄▄▄▄▄▄▄▄▄-49.884.633.926.02.7-133.336.2-50.6-30.5-19.3-33.822.5-1.435.4-1.3-9.3-16.84.9155.4-22.6-53.5-70.7-9.60.20.70.90.30.60.70.60.80.60.50.9NANANANANANANANANANANANA
 us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss▅▃▅▅█▁▄▅▆▆▄▄▄▃▄▄▅▅▃▄▅▅▄▅▄▅▅▄▅▅▄▅▃▄0.9-2.51.01.45.7-5.40.10.72.12.8-0.30.1-0.7-1.7-0.30.10.60.4-2.3-0.30.81.7-0.80.3-1.20.90.4-0.60.50.3-0.50.9-2.9-0.4NANANANANANANANANANANANA
us-gaap:OtherNonoperatingIncomeExpense ▅▅▅▄▄▄▂▃▃▃▃▃▅█▁▄▄▃▄▄▂▃▄▄▄▄▃▄▄▄▃▄▅▄▂▃▃▃▁▃▃▄▂▃▃▃12.410.512.28.06.55.4-5.51.3-0.3-0.71.1-1.712.831.3-12.64.83.81.23.43.5-6.10.75.85.86.57.11.19.27.54.52.14.713.34.1-3.62.22.80.3-12.81.60.63.3-3.52.12.62.6
us-gaap:PreferredStockDividendsIncomeStatementImpact ██████████▅▄▂▁▁▁▁13.813.813.713.813.813.813.713.813.813.88.15.61.30.00.00.00.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ProfitLoss ▅█▆▃▅▆▃▅█▇▅▁▅█▄▅▄▇▆▅▅▇▅▅▄█▆▅▆█56.9296.587.8-172.9-4.775.6-139.36.6296.9218.9-11.7-339.524.5276.1-52.414.0-44.4211.388.827.228.6179.759.4-4.9-27.7275.3154.231.478.2266.2NANANANANANANANANANANANANANANANA
us-gaap:RegulatedOperatingRevenue ▂▆▃▁▁▆▅▁▂█▅▁▂▇▄▁986.01545.61211.0902.5962.71605.51397.2931.51010.41869.81461.7895.01007.01750.81368.3917.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax ▂▄▃▁▂▄▃▁▂▆▄▁▂▅▄▁▂▅▃▁▁▄▂▁▃▇▅▂▃█▅▂▃▅▄▂▂▅▄▂▃▇▅▂▃█952.41506.51153.1861.5932.71525.91358.7891.0969.21834.51436.0855.8982.11717.21368.3883.4990.71598.61297.0861.3897.61436.61097.8817.21169.02149.71691.11123.91335.12320.51596.81076.81212.31782.21410.3956.21038.81658.71490.51068.71228.32232.21752.01138.11171.12358.7
us-gaap:Revenues ▂▄▂▁▂▅▃▂▂▆▃▁▂▅▄▁▂▅▃▁▁▄▂▁▃▇▅▂▃█▅▂▃▅▄▂▂▅▄▂▃▇▅▂▃█986.01545.61002.5902.5962.71605.51241.7931.51010.41869.81338.3895.01007.01750.81368.3917.0990.71598.61297.0861.3897.61436.61097.8817.21169.02149.71691.11123.91335.12320.51596.81076.81212.31782.21410.3956.21038.81658.71490.51068.71228.32232.21752.01138.11171.12358.7
  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 ▅▅▅▆▅▆▆▅▅▅▅▄▄▃▃▃▂▂▂▂▁▁▁▁█▇▇▆▆▆▆▅▅▅▅▄▄▄▄▃▃▃▃22313.822194.522040.522701.522436.522592.722659.822132.321974.221889.921804.020699.420307.920098.519961.719269.518822.718635.918691.918067.217617.217471.417492.517055.925606.924898.924866.323710.123257.823107.322653.922084.121621.621636.421844.720838.620409.420445.920708.319742.119346.319478.819938.8NANANA
 us-gaap:Liabilities dei:LegalEntity nix:Rosewater▁▁█8.48.420.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LiabilitiesAndStockholdersEquity ▅▅▅▆▅▆▆▅▅▅▅▄▄▃▃▃▂▂▂▂▁▁▁▁█▇▇▆▆▆▆▅▅▅▅▄▄▄▄▃▃▃▃22313.822194.522040.522701.522436.522592.722659.822132.321974.221889.921804.020699.420307.920098.519961.719269.518822.718635.918691.918067.217617.217471.417492.517055.925606.924898.924866.323710.123257.823107.322653.922084.121621.621636.421844.720838.620409.420445.920708.319742.119346.319478.819938.8NANANA
us-gaap:StockholdersEquity █▆▆▅▆▆▇▆▇▆▆▄▅▃▂▂▂▂▂▁▁▁▁▁██▇▇▇▇▆▆▆▆▆▅▄▄▄▄▄▄▄6523.15931.65752.25424.95661.85741.45986.75848.55976.25779.65750.95073.75463.04506.24320.14363.04122.84191.14071.23811.63810.63872.33843.53800.36505.96523.56175.36007.36028.36012.15886.65700.95702.75690.75554.35410.85105.35080.54997.34990.05003.45014.34923.2NANANA
  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 ▁▂▂▇▇█▃▁▂▃▄▁▁▂▃▁▁▂▃▁▁▁▂▂▅▅▅▄▄▅▄▃▃▄▅▃▃▄▅▃▃▄▅1384.21593.51659.42820.82859.63225.41853.91378.31578.01915.82055.41369.11315.71633.81763.31332.41280.81471.21762.11378.51259.61395.41577.21637.82335.72261.02466.52011.62054.52320.12159.21745.51707.62031.82352.41838.71751.61970.32248.21860.51745.11985.22448.9NANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue ▂▂▃▂▃▄▃▁▁▃▃▁▂▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁▂▂▁▁▂▁▁▁▂▂▁▁▁▂77.589.1116.558.6142.2203.8139.328.023.7151.0112.841.868.235.029.019.317.928.426.416.115.723.715.531.7496.642.025.417.718.038.026.814.944.5101.436.312.352.838.511.522.259.962.59.210.97.4110.6
us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents ▃▄▅▂▆█▆▁▁▆▅▂▃▂▁▁▁▁▁90.496.7125.667.6153.6213.0148.437.032.4160.8121.153.881.144.738.428.332.839.236.0NANANA45.2NANANA49.8NANANANANANANANANANANANANANANANANANANA
us-gaap:AccountsReceivableNetCurrent ▂▄▄▁▂▃▄▂▄▇▆▁▂▅▅▁▂▄▄▁▁▃▃▁▃▇▆▂▄█▆▂▃▆▅▁▂▃▄▁▂▆▆563.7794.5791.3521.4545.7716.5856.9539.3870.21132.11058.5500.4584.8973.8898.9480.0545.2813.8847.0471.0474.1647.9660.0500.5672.71152.01070.1639.3824.01271.21005.8591.0716.51070.3907.3526.2553.3730.3854.8512.5638.31063.21079.3NANANA
us-gaap:InventoryRawMaterialsAndSupplies ███▆▆▆▅▅▄▄▃▃▃▃▄▃▂▃▃▃▃▂▁▁▄▄▄▄▄▃▃▃▅▄▃▃▃▂▁▁▁▁▁143.5145.6141.5127.0131.8130.9120.2115.1111.9107.3101.097.799.9104.3105.9102.396.797.5101.7100.1102.694.886.884.2112.4109.0106.0106.4106.0104.8101.299.9114.9111.497.499.799.589.887.687.087.084.483.8NANANA
us-gaap:OtherAssetsCurrent ▄▂▂▂▃▄▃▂▂▃▃▂▂▃▃▁▂▃▃▁▂▃▂▁▃▄▄▂▇▇▇▅▅▅█▆▆▆▆▂▂▂▂187.4109.386.0112.6142.6182.8149.785.4103.1144.2129.589.7109.1155.5132.865.891.3139.1130.664.189.8133.5107.575.9133.2187.3169.5103.6320.9321.1330.6246.1224.4228.1357.2280.8274.2277.4261.8119.7100.4119.7120.8NANANA
  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 NANA24179.9NANANA24541.9NANANA22819.5NANANA21649.9NANANA20049.7NANANA18988.1NANANA25642.1NANANA23664.2NANANA21940.9NANANA20518.5NANANA19633.5NANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:CommonUtilityNANA197.3NANANA153.3NANANA155.8NANANA141.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:ConstructionWorkInProcessNANA572.6NANANA457.3NANANA474.8NANANA950.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:ElectricUtilityNANA6478.0NANANA8902.3NANANA8374.2NANANA7403.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:GasDistributionUtilityNANA14010.2NANANA14989.7NANANA13776.0NANANA12531.0NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:NonUtilityAndOtherNANA2746.1NANANA39.3NANANA38.7NANANA623.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType nix:RenewableGenerationAssetsNANA175.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment NANA7560.4NANANA7629.7NANANA7277.0NANANA7290.4NANANA6981.7NANANA6876.6NANANA9625.0NANANA9299.1NANANA9025.0NANANA8718.4NANA8528.08492.6NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType nix:CommonUtilityNANA109.3NANANA79.5NANANA74.6NANANA52.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType nix:ElectricUtilityNANA2305.0NANANA3973.8NANANA3809.5NANANA3673.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType nix:GasDistributionUtilityNANA3292.9NANANA3556.0NANANA3373.8NANANA3227.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType nix:NonUtilityAndOtherNANA1853.1NANANA20.4NANANA19.1NANANA336.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType nix:RenewableGenerationAssetsNANA0.1NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PropertyPlantAndEquipmentNet NANA16619.5NANANA16912.2NANANA15542.5NANANA14359.5NANANA13068.0NANANA12111.5NANANA16017.1NANANA14365.1NANANA12915.9NANANA11800.1NANA11140.611097.0NANANA
 us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity nix:Rosewater▁▄█172.8174.2175.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures NANANA0.91.41.31.32.22.32.12.12.64.25.05.55.66.06.56.66.56.76.76.96.7452.3447.9452.6443.5437.1407.1373.7327.8279.4260.8243.3215.7211.5204.8204.7200.2197.2202.6200.9NANANA
us-gaap:Goodwill ▁▁▁▁▁▁▁▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂███████████████████1485.91485.91485.91485.91485.91485.91485.91690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.71690.73666.23666.23666.23666.23666.23666.23666.23666.23666.23666.23677.33677.33677.33677.33677.33677.33677.33677.33677.3NANANA
us-gaap:OperatingLeaseRightOfUseAsset NANA39.9NANANA64.260.959.053.8NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent ▁▁▁▁▁▁▁▂▂▂▂▂▂▂▁▁▁▁▁▁▁▁▁▁▇▆▇▆▆▆▆▇▇▇█▇███▇▇▇▇3523.03514.93509.63563.73575.33568.13663.54053.44044.84022.14000.03938.83940.53801.83629.33681.73671.53675.23661.93627.93604.83607.33609.23524.95709.95697.95719.75456.85475.55519.35551.95896.85971.66034.56138.76045.36140.36212.16304.25966.15955.96011.86044.4NANANA
  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 ▄▄▅▃▃▄▆▄▄▆█▃▃▄▅▃▃▃▄▂▂▃▃▂▃▄▆▃▃▆▅▂▃▄▄▂▂▂▃▁▂▃▅480.4554.9589.0410.3402.5505.6666.0494.9552.2675.2883.8433.7455.0497.3625.6447.4451.1461.6539.4352.2371.2392.7433.4349.2429.2563.9670.6427.7459.6714.4619.0369.6393.0527.4538.9300.1292.1380.7434.8244.4316.2429.6581.8NANANA
us-gaap:ContractWithCustomerLiabilityCurrent ▁▁▇▆▂▂█148.1146.7243.3229.2163.1163.2256.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:DividendsPayableCurrent ▁█94.4105.7NA99.988.599.8NA94.182.794.0NA82.470.865.80.058.957.056.70.053.153.049.70.049.3NA82.40.082.182.078.70.078.378.174.80.074.368.3NA0.064.764.664.50.1NANANA
us-gaap:LiabilitiesCurrent ▁▃▃▆▅█▇▆▇██▆▃▅▅▃▄▇▆▄▄▃▄▂▃▄▇▅▆▆▅▅▂▅▆▄▄▇▇▄▃▅▇1706.92258.82279.43446.83227.74161.83745.83339.73813.74015.24036.83411.22560.43226.23178.42566.82778.33664.13452.22911.62696.22495.92657.52073.32524.32758.43954.93048.53431.43340.83178.43005.62068.02974.43301.62727.12662.33718.43646.42887.22558.13096.13649.4NANANA
us-gaap:OperatingLeaseLiabilityCurrent NANA10.3NANANA13.210.59.49.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseLiabilityCurrent nix:LeaseType nix:OperatingLeaseMemberNANA10.3NANANA13.210.59.49.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesCurrent ▅▃▂▂▃▃▃▂▂▁▁▁▁▂▂▂▁▁▂▁▁▂▂▂▆▆▇█▇▆▆▆▆▅▆▅▄▅▆▅▄▅▇262.8164.7113.6119.1140.5180.9144.1120.786.279.558.854.575.6109.590.8119.278.776.282.767.568.2103.1114.7121.7313.8317.1378.1408.6347.4323.8327.6308.7283.8269.7309.7232.7219.8239.7301.0254.5230.0249.2336.4NANANA
us-gaap:TaxesPayableCurrent ▅█▆▂▄▅▅▂▂▅▅▂▂▄▄▂▂▅▄▁▁▄▃▁▅▇▇▃▄▇▆▃▄▆▅▃▃▅▅▂▃▆▅232.0301.5244.1147.1195.7223.8231.6157.8167.3232.8222.7150.0165.8212.8208.1148.4152.2216.6195.4130.9140.9203.1183.5137.0221.5287.1266.7189.3216.1278.6254.8181.3202.1258.2235.5172.0185.5237.3220.9157.8179.5244.4221.1NANANA
  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:LiabilitiesNoncurrent ▂▁▁▁▁▂▂▃▂▂▂▃▃▃▂▂▃▃▃▃▃▃▂▂██▇▆▆▆▆▆▆▆▆▅▅▅▅▄▄▄▄4791.84707.74703.54620.94736.84871.65071.15090.35074.64985.04910.95120.05192.05079.34951.04821.15144.25190.05110.35247.85253.25197.75043.05048.86745.66712.96580.26256.96157.56115.95995.76288.56234.26167.46169.75881.05834.95812.65797.55527.65444.85440.85430.1NANANA
us-gaap:LongTermDebtAndCapitalLeaseObligations ████▇▅▅▅▄▄▄▄▄▄▅▅▃▁▂▂▂▂▂▂▇▆▆▆▅▅▅▄▅▃▃▃▃▁▂▂▂▂▂9201.69202.39219.89208.98810.27817.97856.27853.87109.77110.17105.47094.57092.57286.87512.27518.66777.45590.76058.26096.25857.25905.55948.56133.58881.17957.98155.98397.47640.67638.57593.27089.17616.76803.96819.16819.76806.95834.46267.16337.36340.05927.65936.1NANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet █▇▂▁▃▂▃1587.51573.61470.61439.51477.41451.31485.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent NANA303.5NANANA314.3NANANA275.4NANANA293.1NANANA296.9NANANA299.3NANANA250.4NANANA-259.3NANANA-461.8NANANA-466.9NANANANANANANA
 us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanType us-gaap:PensionPlansDefinedBenefitNANA29.2NANANA54.8NANANA110.6NANANA39.6NANANA412.0NANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterest ▅█▁90.494.185.6NANANANANANANANANANANANANANANANANANANANANA950.0946.20.0NANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesNoncurrent █▆▃▂▂▂▂▂▂▂▁▂▁▂▂▂▂▂▂▁▁▂▂▁▃▃▃▃▂▂▂▂▂▂▂▃▂▃▂▂▁▁▁566.8444.5286.1214.7198.8187.3218.5224.7222.8218.3177.9215.0184.8191.7194.4187.8188.9199.2200.5182.8187.0188.4208.1186.6270.6294.0291.1297.7224.3219.4216.0219.1216.4225.0226.2246.2242.1247.8244.7193.1157.8163.4162.0NANANA
us-gaap:OperatingLeaseLiabilityNoncurrent NANA29.9NANANA51.650.549.344.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:OperatingLeaseLiabilityNoncurrent nix:LeaseType nix:OperatingLeaseMemberNANA29.9NANANA51.650.549.344.5NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA5.2NANANA9.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo nix:LeaseType nix:FleetLeaseNANA27.7NANANA28.3NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo nix:LeaseType nix:OperatingLeaseMemberNANA5.2NANANA9.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA4.7NANANA8.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree nix:LeaseType nix:FleetLeaseNANA24.9NANANA23.4NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree nix:LeaseType nix:OperatingLeaseMemberNANA4.7NANANA8.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA4.5NANANA7.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour nix:LeaseType nix:FleetLeaseNANA22.0NANANA19.9NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour nix:LeaseType nix:OperatingLeaseMemberNANA4.5NANANA7.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA3.7NANANA6.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive nix:LeaseType nix:FleetLeaseNANA19.0NANANA15.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive nix:LeaseType nix:OperatingLeaseMemberNANA3.7NANANA6.6NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA18.2NANANA31.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive nix:LeaseType nix:FleetLeaseNANA21.5NANANA15.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive nix:LeaseType nix:OperatingLeaseMemberNANA18.2NANANA31.7NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  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 █▆▆▅▆▆▇▆▇▆▆▄▅▃▂▂▂▂▂▁▁▁▁▁██▇▇▇▇▆▆▆▆▆▅▄▄▄▄▄▄▄6523.15931.65752.25424.95661.85741.45986.75848.55976.25779.65750.95073.75463.04506.24320.14363.04122.84191.14071.23811.63810.63872.33843.53800.36505.96523.56175.36007.36028.36012.15886.65700.95702.75690.75554.35410.85105.35080.54997.34990.05003.45014.34923.2NANANA
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest █▃▁6613.56025.75837.8NA5661.85741.45986.7NANANA5750.9NANANA4320.1NANANANA3811.63810.63872.33843.53800.37455.97469.76175.3NANANANANANANANANANANANANANANANANANANA
us-gaap:CommonStockValue ███▇▇▇▇▇▇▇▇▇▇▅▅▅▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▄▃▃▃▃▂▂▁▁▁▁▁3.93.93.93.83.83.83.83.83.83.83.83.73.73.43.43.43.33.33.33.33.23.23.23.23.23.23.23.23.23.23.23.23.13.13.13.12.92.92.82.82.82.82.8NANANA
us-gaap:AdditionalPaidInCapitalCommonStock ███▇▇▇▇▇▇▇▇▆▆▅▅▅▄▄▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▁▁▁▁▁▁▁6728.06892.96890.16684.26676.56671.56666.26426.56417.16406.56403.56161.06151.25540.55529.15518.55225.35174.75153.95135.65118.35102.55078.05078.65065.15048.44787.64764.74734.74715.64690.14672.94646.04627.54597.64579.34221.04198.94167.74149.44132.94120.14103.9NANANA
us-gaap:RetainedEarningsAccumulatedDeficit ▁▁▁▁▂▂▂▂▂▂▂▂▃▃▃▃▃▃▃▃▃▃▂▂███▇██▇▇▇▇▇▇▇▇▇▇▇▇▇-1704.1-1669.8-1765.2-1849.6-1576.7-1483.4-1370.8-1231.6-1144.0-1358.0-1399.3-1387.5-965.5-919.2-1073.1-1020.6-975.6-874.2-972.2-1060.9-1067.4-1042.9-1123.3-1182.71561.11597.51494.01339.91390.61394.41285.51133.81164.11170.51059.6925.7980.9980.0917.0922.6952.6978.3901.8NANANA
us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax ▄▆▃▂▁▁▅▄▅▆▇█▇▇▇▇▇▇▇▃▃▅▇▇▇▇▆▇▇▇▇▆▆▆▆▆▆▆▆▆▆▆▆-123.6-75.5-156.7-193.6-221.9-230.6-92.6-130.3-80.8-52.8-37.22.5-20.9-19.0-43.4-43.7-35.6-19.6-25.1-179.0-156.3-103.8-35.1-19.6-44.4-46.6-50.6-41.6-41.4-42.5-43.6-60.4-62.0-62.3-65.5-56.8-59.0-60.9-59.7-54.4-54.5-56.7-57.9NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedDefinedBenefitPlansAdjustment███▇▇▇▇▆▆▆▆▇▇▇█▇▇▇▇▇▇▇▇█▅▄▄▇▇▇▇▃▂▂▁-14.9-15.7-14.8-16.8-17.7-18.0-18.7-20.1-20.5-20.9-21.8-16.2-17.0-17.2-14.2-16.1-17.2-17.4-17.6-18.4-18.6-18.8-19.1-14.0-24.4-27.1-27.3-17.6-17.4-17.3-17.5-34.0-34.1-36.8-39.5NANANA-32.8NANANA-26.8NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges▄▅▃▂▁▁▅▄▅▆▇█▇▇▆▇▇▇▇▂▃▅▇▇▇▇▇▇▇▇▇▇▇▇▇-113.1-63.3-147.9-181.8-207.8-210.5-77.2-113.4-62.8-32.3-13.020.8-1.7-0.3-29.4-28.1-18.8-2.0-6.9-162.3-139.7-86.2-15.5-5.9-20.0-20.7-23.6-23.9-24.5-25.2-25.8-26.6-27.2-27.7-28.6NANANA-31.8NANANA-34.8NANANA
 us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss▇▆█▇▆▁▆▆▅▃▁▁▁▂▃▃▃▃▂▄▅▄▃▃▃▄▃▃▃▃▃▃▂▅▅4.43.56.05.03.6-2.13.33.22.50.4-2.4-2.1-2.2-1.50.20.50.4-0.2-0.61.72.01.2-0.50.30.01.20.3-0.10.50.0-0.30.2-0.72.22.6NANANA4.9NANANA3.7NANANA
us-gaap:TreasuryStockValue ███████████████▇▇▇▇▇▇▇▆▆▆▆▄▄▄▄▃▃▃▃▂▂▂▂▁▁▁▁▁99.999.999.999.999.999.999.999.999.999.999.999.999.999.595.994.694.693.188.787.487.286.779.379.279.179.058.958.958.858.648.648.648.548.140.540.540.540.430.530.430.430.227.4NANANA
us-gaap:MinorityInterest ▅█▁90.494.185.6NANANANANANANANANANANANANANANANANANANANANA950.0946.20.0NANANANANANANANANANANANANANANANANANANA
us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders 0.3NANANANANANANANANANANANANANANANANANANANANA0.0232.0-4.90.0NANANANANANANANANANANANANANANANANANANANA
  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 ▆▇▅▅▆▆▆▆▇▇▁▅▇▆▅▃▅▇▆▄▅▆▆▄▇█▇▅▆▇▆▅▇▇▆▅▆▇▄▄▆▇▇▃▆▄254.7448.3245.4150.9337.8369.9351.5305.6527.1399.1-387.1117.7421.3388.2212.6-121.8240.3411.1271.344.9184.2302.9262.978.3511.3604.3433.1235.5257.0394.0358.2184.1445.4449.1333.7170.0291.8480.076.158.1313.9422.1392.9-70.0319.283.3
us-gaap:NetCashProvidedByUsedInInvestingActivities ▁▁▃▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▁▁▁▂▁█▁▁▁▁▁▁▁▁▁▂▁▁▂▂▂▁▂▂▂▁▂▂-460.6-401.8520.8-513.3-402.0-484.6-528.6-495.8-522.6-375.4-549.6-505.4-472.2-398.9-502.4-514.9-447.0-344.2-414.7-453.2-399.7-315.3-461.33400.0-604.9-388.9-604.4-614.6-489.7-407.9-640.1-533.2-472.0-246.1-473.9-382.4-274.2-294.7-347.4-378.5-248.3-175.1-182.2-367.2-199.5-194.4
us-gaap:NetCashProvidedByUsedInFinancingActivities ▇▆▆▇▇▇▇▇▆▇█▇▇▇▇▇▇▆▇▇▇▇▇▁▇▆▇▇▇▇▇▇▇▆▇▇▇▆▇▇▆▆▆▇▆▇199.6-75.4-708.2276.44.8179.3288.5194.8-132.916.01004.0360.487.317.0299.3638.1196.2-64.9153.7408.7207.520.6182.2-3943.2548.2-198.8179.0378.8212.725.1293.8319.5-30.3-137.9164.2171.9-3.3-158.3260.6282.7-68.2-193.7-212.4440.7-222.9205.3
  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:DepreciationDepletionAndAmortization ███▇▇███▇▇▅▄▃▃▃▃▃▃▃▂▂▂▂▂▆▅▄▄▄▄▃▃▃▃▃▁▄▃▁▂▂▂▃▄▄▄186.3185.0183.5180.6177.5184.3182.2182.2177.9175.1161.8148.5144.6144.7141.8143.0142.2143.3141.1136.3136.9132.8133.4132.5167.4157.5154.7153.0149.1148.7145.9144.5143.3143.6141.8126.0148.0146.1129.9134.9134.5138.9141.8153.1151.6149.8
us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet ▁█16.989.3NA72.7-71.2147.1NA-155.8-18.227.2NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInOperatingActivities ▆▇▅▅▆▆▆▆▇▇▁▅▇▆▅▃▅▇▆▄▅▆▆▄▇█▇▅▆▇▆▅▇▇▆▅▆▇▄▄▆▇▇▃▆▄254.7448.3245.4150.9337.8369.9351.5305.6527.1399.1-387.1117.7421.3388.2212.6-121.8240.3411.1271.344.9184.2302.9262.978.3511.3604.3433.1235.5257.0394.0358.2184.1445.4449.1333.7170.0291.8480.076.158.1313.9422.1392.9-70.0319.283.3
us-gaap:NetIncomeLoss ▅█▆▃▅▆▃▅█▇▅▁▅█▄▅▄▇▆▅▅▇▅▅▄█▆▅▆█▆▅▆█▆▅▅▇▅▅▅▇▅▅▅▇60.3295.584.4-172.9-4.775.6-139.36.6296.9218.9-11.7-339.524.5276.1-52.414.0-44.4211.388.827.228.6179.759.4-4.9-36.4268.4154.231.478.2266.2151.848.171.7260.5134.019.369.4193.414.734.738.9205.231.833.228.1197.3
us-gaap:ProfitLoss ▅█▆▃▅▆▃▅█▇▅▁▅█▄▅▄▇▆▅▅▇▅▅▄█▆▅▆█56.9296.587.8-172.9-4.775.6-139.36.6296.9218.9-11.7-339.524.5276.1-52.414.0-44.4211.388.827.228.6179.759.4-4.9-27.7275.3154.231.478.2266.2NANANANANANANANANANANANANANANANA
  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 ▁▁▃▁▁▁▁▁▁▁▁▁▁▁▁▁▁▂▁▁▁▂▁█▁▁▁▁▁▁▁▁▁▂▁▁▂▂▂▁▂▂▂▁▂▂-460.6-401.8520.8-513.3-402.0-484.6-528.6-495.8-522.6-375.4-549.6-505.4-472.2-398.9-502.4-514.9-447.0-344.2-414.7-453.2-399.7-315.3-461.33400.0-604.9-388.9-604.4-614.6-489.7-407.9-640.1-533.2-472.0-246.1-473.9-382.4-274.2-294.7-347.4-378.5-248.3-175.1-182.2-367.2-199.5-194.4
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▆▆▇▇▆▇▇▇▇▅▇▇▇▆▇▇▆▅▆▆▆▅▆▁█▆██▇▆█▇▆▆▇▆▅▅▅▅▄▄▄▄▄▃431.1367.0465.9472.9367.2452.1492.4466.5489.8353.7521.6464.1462.5370.0479.4484.2420.2312.0391.8410.9371.5301.0437.3-67.7583.6407.5586.8588.8466.6386.3582.6495.6432.4369.3474.5404.8326.9292.6351.0329.2235.6209.4250.1216.8198.1138.8
  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 ▇▆▆▇▇▇▇▇▆▇█▇▇▇▇▇▇▆▇▇▇▇▇▁▇▆▇▇▇▇▇▇▇▆▇▇▇▆▇▇▆▆▆▇▆▇199.6-75.4-708.2276.44.8179.3288.5194.8-132.916.01004.0360.487.317.0299.3638.1196.2-64.9153.7408.7207.520.6182.2-3943.2548.2-198.8179.0378.8212.725.1293.8319.5-30.3-137.9164.2171.9-3.3-158.3260.6282.7-68.2-193.7-212.4440.7-222.9205.3
us-gaap:ProceedsFromIssuanceOfLongTermDebt NANA0.01974.0NANA0.0750.0NANA0.00.0NANA500.0750.0NANA0.0500.0NANA0.0-2745.9NANA0.0748.4NANA492.30.0NANA0.00.0NANA494.70.0NANANANANANA
us-gaap:PaymentsOfDividendsCommonStock ██▇▇▇▇▆▆▆▆▅▅▄▄▃▂▂▂▂▂▁▁▁▁▇▇▇▇▇▇▆▆▆▆▆▅▄▄▄▄▄▄▄▄▄▄86.386.280.580.480.480.374.774.774.674.570.870.866.065.758.957.056.756.553.253.049.749.649.449.382.682.182.182.078.778.578.378.174.874.774.468.465.365.164.564.664.564.264.263.863.963.7
  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 End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3900000.03900000.03900000.03800000.03800000.03800000.03800000.03800000.03800000.03800000.03800000.03700000.03700000.03400000.03400000.03400000.03300000.03300000.03300000.03300000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03100000.03100000.03100000.03100000.02900000.02900000.02800000.02800000.02800000.02800000.02800000.02800000.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Par Or Stated Value Per Share

us-gaap:CommonStockParOrStatedValuePerShare

us-gaap:CommonStockParOrStatedValuePerShare


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value0.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.010.10.010.010.010.010.010.010.010.01
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

Preferred Stock Par Or Stated Value Per Share

us-gaap:PreferredStockParOrStatedValuePerShare

us-gaap:PreferredStockParOrStatedValuePerShare


Preferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-312018-12-272018-09-302018-06-302015-12-312014-12-312013-12-312012-12-312011-12-31
Value0.010.010.010.010.010.010.010.010.010.010.011000.01000.00.010.010.010.010.01
Percentage of PreferredStockParOrStatedValuePerShare100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PreferredStockParOrStatedValuePerShare us-gaap:StatementClassOfStock

us-gaap:SeriesCPreferredStock


Preferred
Period End2021-04-19
Value0.01
Percentage of PreferredStockParOrStatedValuePerShare0.0

us-gaap:PreferredStockParOrStatedValuePerShare us-gaap:StatementClassOfStock, us-gaap:SubsequentEventType

us-gaap:SeriesCPreferredStock, us-gaap:SubsequentEvent


Preferred
Period End2021-04-19
Value0.01
Percentage of PreferredStockParOrStatedValuePerShare0.0

Shares Issued

us-gaap:SharesIssued

us-gaap:SharesIssued


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value392392391383382382382373373373372363362337337336325324323319316313676310281281278276274274
Percentage of SharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:SharesIssued us-gaap:StatementEquityComponents

us-gaap:CommonStock


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-05-042018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value39639639538738638638637737737637636736624341340340329328326322318315983312291283280277275275
Percentage of SharesIssued101.0101.0101.0101.0101.0101.0101.0101.1101.1101.1101.1101.1101.10.0101.2101.1101.1101.1101.1101.1101.0100.8100.7100.6100.6100.5100.5100.4100.4

us-gaap:PreferredStock


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-312015-12-31
Value1.3030.440.440.440.440.440.440.440.440.440.420.40.40.00.00.00.0
Percentage of SharesIssued0.30.10.10.10.10.10.10.10.10.10.10.10.10.00.00.00.0

us-gaap:TreasuryStock


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-3.963-3.9633.963-3.963-3.963-3.9633.963-3.963-3.9633.9633.9633.9633.9633.9463.797-3.749-3.741-3.6883.504-3.071-2.599-2307.0-2010.0-1.571-1.406-1.309-1.117-1.113
Percentage of SharesIssued-1.0-1.01.0-1.0-1.0-1.01.0-1.1-1.11.11.11.11.11.21.1-1.1-1.1-1.11.1-1.0-0.8-0.7-0.6-0.6-0.5-0.5-0.4-0.4

Common Stock Shares Authorized

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesAuthorized


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value600600600600600600600600600400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400400
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesOutstanding


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value392392391383382382382373373373372363362337337336325324323322322321319318317317316315315314313313312311310309284283278281280279278276
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value422393383383384374375374363355338332325325323322322321317317316316315313313312300295293289287285279278277
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
Value393392383383383374373373363354338331325323322321320318317316315315314312312311290284282280280279278277276
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

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
Value0.120.720.18-0.49-0.050.16-0.41-0.020.760.55-0.05-0.950.070.82-0.160.04-0.140.650.280.080.090.560.19-0.02-0.110.850.490.10.250.850.480.160.230.840.430.060.250.680.050.120.140.730.110.120.10.71
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
Value0.110.720.18-0.49-0.050.16-0.41-0.020.750.55-0.05-0.950.070.81-0.160.04-0.140.650.270.080.090.560.19-0.02-0.110.850.490.10.250.850.480.160.230.830.430.060.230.660.040.120.140.720.10.120.10.71
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 Including Portion Attributable To Noncontrolling Interest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest

us-gaap:ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest


Comprehensive
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value8.8377124-144.64.0-62.4-101.6-42.9268203-51.4-316.122310-52.15.9-60.42162424.5-23.911143-4.6-25.52771453179267
Percentage of ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.925.10.0-16.80.4-4.10.0-4.827.711.10.0-36.92.318.1-3.80.7-6.113.618.70.5-2.77.74.0-0.6-2.212.98.62.85.911.5

Cost Of Goods And Service Excluding Depreciation Depletion And Amortization

us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization

us-gaap:CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization


Cost
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value228476315143188462404196253680
Percentage of CostOfGoodsAndServiceExcludingDepreciationDepletionAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax24.031.60.016.620.230.30.022.126.237.1

Gains Losses On Extinguishment Of Debt

us-gaap:GainsLossesOnExtinguishmentOfDebt

us-gaap:GainsLossesOnExtinguishmentOfDebt


Gains
Period End2020-12-312020-09-302019-12-312019-09-302019-06-302018-12-312018-07-162018-09-302018-06-302017-12-312017-09-302017-06-302016-12-312016-09-302016-06-302015-12-312015-09-302015-06-302014-12-312014-09-302014-06-302011-12-13
Value-0.1-243.40.00.00.00.033-33.0-12.50.00.0-111.50.00.00.00.00.0-97.20.00.00.0-53.9
Percentage of GainsLossesOnExtinguishmentOfDebt100.0100.00.00.00.00.0100.0100.0100.00.00.0100.00.00.00.00.00.0100.00.00.00.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0-28.30.00.00.00.00.0-3.9-1.30.00.0-11.30.00.00.00.00.0-8.30.00.00.00.0

us-gaap:GainsLossesOnExtinguishmentOfDebt us-gaap:DebtInstrument

nix:NoteRedeemedSeptember2020


Gains
Period End2020-09-30
Value11
Percentage of GainsLossesOnExtinguishmentOfDebt-4.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:NoteRedeemedSeptember20200.0

nix:SeniorNoteRedeemedAugustSeptember2020


Gains
Period End2020-09-30
Value231
Percentage of GainsLossesOnExtinguishmentOfDebt-95.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:SeniorNoteRedeemedAugustSeptember20200.0

Gross Profit

us-gaap:GrossProfit

us-gaap:GrossProfit


Gross
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
Value121190296216051397931101018691461895100717501368683713104685664366294076160895013431130893963125910498338521106943739807102889074576510619257187321072
Percentage of GrossProfit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.0104.8103.2105.20.0104.5104.3101.90.0104.6102.5102.0100.077.472.165.566.074.773.865.469.474.481.362.566.879.572.254.365.777.470.362.166.977.477.762.059.769.862.347.552.863.162.545.5

Income Loss From Continuing Operations Before Income Taxes Domestic

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic


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
Value70359144-237.81.260-136.8-3.6369277-165.4-434.03033816516-70.9332140324629113120-42.7426236571184292357710433319031108296315369312572743307
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax7.423.80.0-27.60.14.00.0-0.438.115.10.0-50.73.119.712.11.9-7.220.810.83.75.120.311.92.5-3.719.814.05.18.818.514.87.28.618.713.53.310.417.92.15.05.714.03.32.43.713.0

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
Value136256-64.95.9-14.92.5-10.27259-153.7-94.55.5622172.5-26.6121518.517111665.8-15.31508225391628227321186311371028.3173010721-5.615109
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 RevenueFromContractWithCustomerExcludingAssessedTax1.44.20.0-7.50.6-1.00.0-1.17.43.20.0-11.00.63.715.90.3-2.77.64.01.01.97.86.10.7-1.37.04.92.33.07.05.22.62.76.64.51.23.66.20.61.62.44.81.2-0.51.34.7

Interest Expense

us-gaap:InterestExpense

us-gaap:InterestExpense


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value848485959792939594958883889392878785888586909494117111115109109109110103102981031071031039695948997979898
Percentage of InterestExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.95.60.011.110.46.10.010.89.75.20.09.79.05.46.810.08.95.36.89.99.66.38.611.610.05.26.89.88.24.76.99.68.45.57.411.39.96.26.59.07.74.05.68.68.44.2

Interest Income Expense Nonoperating Net

us-gaap:InterestIncomeExpenseNonoperatingNet

us-gaap:InterestIncomeExpenseNonoperatingNet


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value700000.0900000.01100000.01300000.01400000.01700000.02300000.02100000.01200000.02100000.02400000.01400000.01100000.01700000.01400000.01400000.0900000.0900000.0
Percentage of InterestIncomeExpenseNonoperatingNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.10.00.20.20.10.00.20.10.10.00.20.10.10.10.20.10.1

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value6029584-172.9-4.775-139.36.6296218-11.7-339.524276-52.414-44.421188272817959-4.9-36.4268154317826615148712601341969193143438205313328197
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.319.60.0-20.1-0.55.00.00.730.611.90.0-39.72.516.1-3.81.6-4.513.26.83.23.212.55.4-0.6-3.112.59.12.85.911.59.54.55.914.69.52.06.711.71.03.23.29.21.82.92.48.4

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest


Net
Period End2021-06-302021-03-312020-12-31
Value-3400000.01000000.03400000.0
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.40.10.0

Net Income Loss Available To Common Stockholders Basic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic

us-gaap:NetIncomeLossAvailableToCommonStockholdersBasic


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value4628170-186.7-18.561-153.0-7.2283205-19.8-345.123276-52.414-44.4
Percentage of NetIncomeLossAvailableToCommonStockholdersBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.918.70.0-21.7-2.04.10.0-0.829.211.20.0-40.32.416.1-3.81.6-4.5

Net Income Loss Available To Common Stockholders Diluted

us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted

us-gaap:NetIncomeLossAvailableToCommonStockholdersDiluted


Net
Period End2021-06-302020-06-30
Value46-18.5
Percentage of NetIncomeLossAvailableToCommonStockholdersDiluted100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.9-2.0

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value-72100000.0-74100000.0-73500000.0-330600000.0-90500000.0-87500000.0-98800000.0-94600000.0-94400000.0-96300000.0-87000000.0-118100000.0-88400000.0-61800000.0-105000000.0-83100000.0-195400000.0-84000000.0-84600000.0-81500000.0-92100000.0-89800000.0-88500000.0-89100000.0-207800000.0-103900000.0-114700000.0-100400000.0-101600000.0-104600000.0-108400000.0-99000000.0-88700000.0-94500000.0-107500000.0-105700000.0-100400000.0-103000000.0-163600000.0-94100000.0-93800000.0-86500000.0-197700000.0-95500000.0-95800000.0-96200000.0
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-7.6-4.90.0-38.4-9.7-5.70.0-10.6-9.7-5.20.0-13.8-9.0-3.6-7.7-9.4-19.7-5.3-6.5-9.5-10.3-6.3-8.1-10.9-17.8-4.8-6.8-8.9-7.6-4.5-6.8-9.2-7.3-5.3-7.6-11.1-9.7-6.2-11.0-8.8-7.6-3.9-11.3-8.4-8.2-4.1

Operating Costs And Expenses

us-gaap:OperatingCostsAndExpenses

us-gaap:OperatingCostsAndExpenses


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value8431112992809871145714358405461495
Percentage of OperatingCostsAndExpenses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax88.673.80.094.093.495.50.094.356.481.5

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
Value1424332189291148-38.091463374-78.4-315.911840027099124416224113138381219109165530351157219533344176193428306137208399185147163399252123139403
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 RevenueFromContractWithCustomerExcludingAssessedTax14.928.80.010.89.89.70.010.247.820.40.0-36.912.123.319.711.312.626.117.313.215.426.520.013.414.124.720.814.016.423.021.516.416.024.021.714.320.124.112.513.813.317.914.410.811.917.1

us-gaap:OperatingIncomeLoss us-gaap:StatementBusinessSegments

nix:ElectricOperations


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value7987531308678851408595386134828379125
Percentage of OperatingIncomeLoss56.020.324.5140.194.853.0-224.7154.618.525.4-492.5-42.769.620.729.3125.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax8.45.80.015.19.35.10.015.88.85.20.015.88.44.85.814.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations20.823.20.031.926.122.20.032.022.323.30.030.021.320.70.00.0

nix:GasDistributionOperations


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value61346161-42.21.77869-48.6379275-254.1-455.239321183-15.4
Percentage of OperatingIncomeLoss43.080.173.9-45.51.953.0-183.2-53.481.873.6324.1144.133.080.367.8-15.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.423.00.0-4.90.25.10.0-5.539.115.00.0-53.24.018.713.4-1.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations10.730.80.0-9.30.36.70.0-10.864.719.30.0-112.06.624.50.00.0

us-gaap:CorporateAndOther


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value1.4-1.63.65.03.1-8.8-193.0-1.1-1.23.8-7.34.4-3.1-4.28.0-1.1-5.5-1.23.7-3.4-3.7-3.88.4-8.8-38.9-28.1-21.0-14.3-6.8-5.94.1-4.8-4.8-4.7-1.6-1.4-0.22.6
Percentage of OperatingIncomeLoss1.0-0.41.75.43.4-5.9507.9-1.2-0.31.09.3-1.4-2.6-1.03.0-1.1-4.4-0.31.6-3.0-2.7-1.03.8-8.0-23.6-5.3-6.0-9.1-3.1-1.11.2-2.7-2.5-1.1-0.5-1.0-0.10.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.10.00.60.3-0.60.0-0.1-0.10.20.00.5-0.3-0.20.6-0.1-0.6-0.10.3-0.4-0.4-0.30.8-1.1-3.3-1.3-1.2-1.3-0.5-0.30.3-0.4-0.4-0.3-0.1-0.1-0.00.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther700.0-800.00.02500.01550.0-4400.00.0-550.0-600.01900.00.02200.0-1550.0-2100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Other Comprehensive Income Loss Net Of Tax

us-gaap:OtherComprehensiveIncomeLossNetOfTax

us-gaap:OtherComprehensiveIncomeLossNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value-48.18136288.7-138.037-49.5-28.0-15.6-39.723-1.9330.3-8.1-16.05.5153-22.7-52.5-68.7-15.50.32.22.0-9.0-0.21.11.1161.60.33.2-8.72.21.9-1.2
Percentage of OtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-5.15.40.03.30.9-9.00.0-5.6-2.9-0.90.02.7-0.22.00.0-0.9-1.60.311.9-2.6-5.8-4.8-1.40.00.20.1-0.5-0.00.10.01.10.10.00.2-0.60.20.2-0.1

us-gaap:OtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


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
Value0.8-0.92.00.90.30.71.40.40.40.9-5.60.80.20.21.91.10.20.20.80.20.20.3-5.1-0.22.70.2-9.7-0.2-0.10.2160.12.72.7
Percentage of OtherComprehensiveIncomeLossNetOfTax-1.7-1.15.43.23.4-0.53.7-0.8-1.4-5.814.13.4-10.50.6633.3-13.6-1.23.60.5-0.9-0.4-0.432.9-66.7122.710.0107.8100.0-9.118.298.26.2900.084.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.10.00.10.00.00.00.00.00.00.00.10.00.00.10.10.00.00.10.00.00.0-0.5-0.00.20.0-0.6-0.0-0.00.01.00.00.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax 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:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-49.88433262.7-133.336-50.6-30.5-19.3-33.822-1.435-1.3-9.3-16.84.9155-22.6-53.5-70.7-9.60.20.70.90.30.60.70.60.80.60.50.9
Percentage of OtherComprehensiveIncomeLossNetOfTax103.5104.291.991.931.096.696.0102.2108.9123.785.196.273.7104.4-433.3114.8105.089.1101.099.6101.9102.961.966.731.845.0-3.3-300.063.654.54.837.5166.728.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-5.25.60.03.00.3-8.70.0-5.7-3.1-1.10.02.6-0.12.1-0.1-1.1-1.70.312.0-2.6-6.0-4.9-0.90.00.10.00.00.10.10.00.10.10.00.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax 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:AccumulatedNetUnrealizedInvestmentGainLoss


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
Value0.9-2.51.01.45.7-5.40.10.72.12.8-0.30.1-0.7-1.7-0.30.10.60.4-2.3-0.30.81.7-0.80.3-1.20.90.4-0.60.50.3-0.50.9-2.9-0.4
Percentage of OtherComprehensiveIncomeLossNetOfTax-1.9-3.12.74.965.53.90.3-1.4-7.5-17.90.80.436.8-5.0-100.0-1.2-3.87.3-1.51.3-1.5-2.55.2100.0-54.545.0-4.4300.045.527.3-3.056.2-966.7-12.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.1-0.20.00.20.6-0.40.00.10.20.20.00.0-0.1-0.1-0.00.00.10.0-0.2-0.00.10.1-0.10.0-0.10.00.0-0.10.00.0-0.00.1-0.2-0.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

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
Value1210128.06.55.4-5.51.3-0.3-0.71.1-1.71231-12.64.83.81.23.43.5-6.10.75.85.86.57.11.19.27.54.52.14.7134.1-3.62.22.80.3-12.81.60.63.3-3.52.12.62.6
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 RevenueFromContractWithCustomerExcludingAssessedTax1.30.70.00.90.70.40.00.1-0.0-0.00.0-0.21.31.8-0.90.50.40.10.30.4-0.70.00.50.70.60.30.10.80.60.20.10.41.10.2-0.30.20.30.0-0.90.10.00.1-0.20.20.20.1

Preferred Stock Dividends Income Statement Impact

us-gaap:PreferredStockDividendsIncomeStatementImpact

us-gaap:PreferredStockDividendsIncomeStatementImpact


Preferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-30
Value131313131313131313138.15.61.30.00.00.00.0
Percentage of PreferredStockDividendsIncomeStatementImpact100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.40.90.01.61.50.90.01.51.40.80.00.70.10.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value5629687-172.9-4.775-139.36.6296218-11.7-339.524276-52.414-44.421188272817959-4.9-27.72751543178266
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.019.70.0-20.1-0.55.00.00.730.611.90.0-39.72.516.1-3.81.6-4.513.26.83.23.212.55.4-0.6-2.412.89.12.85.911.5

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312015-06-302015-03-31
Value-3.41.08.76.9
Percentage of ProfitLoss-6.00.3-31.42.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.40.10.70.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302015-06-302015-03-31
Value6029584-172.9-4.775-139.36.6296218-11.7-339.524-36.4268
Percentage of ProfitLoss106.099.796.1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0131.497.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.319.60.0-20.1-0.55.00.00.730.611.90.0-39.72.5-3.112.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Regulated Operating Revenue

us-gaap:RegulatedOperatingRevenue

us-gaap:RegulatedOperatingRevenue


Regulated
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
Value9861545121190296216051397931101018691461895100717501368917
Percentage of RegulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax103.5102.60.0104.8103.2105.20.0104.5104.3101.90.0104.6102.5102.0100.0103.8

us-gaap:RegulatedOperatingRevenue us-gaap:StatementBusinessSegments

nix:ElectricOperations


Regulated
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
Value403402370432356377393467406430403476404423
Percentage of RegulatedOperatingRevenue40.926.030.647.937.023.528.250.240.223.027.653.240.224.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.426.70.050.238.224.70.052.541.923.50.055.641.224.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations105.5106.10.0106.2106.9106.50.0106.4106.0105.50.0106.0104.8105.5

nix:GasDistributionOperations


Regulated
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
Value574113582347060612281003463603143810584186011327
Percentage of RegulatedOperatingRevenue58.273.568.052.163.076.571.849.859.876.972.446.859.875.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax60.375.40.054.665.080.50.052.062.378.40.048.961.377.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations100.8100.80.0103.5101.2104.80.0102.7103.1100.90.0103.0101.1100.9

us-gaap:CorporateAndOther


Regulated
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
Value8.27.3170.20.20.20.20.20.20.20.10.20.20.2
Percentage of RegulatedOperatingRevenue0.80.51.40.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.90.50.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther4100.03650.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

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
Value952150611538619321525135889196918341436855982171713688839901598129786189714361097817116921491691112313352320159610761212178214109561038165814901068122822321752113811712358
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:MajorCustomers

nix:Commercial


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
Value255394301224235389344227236449354221243425
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.826.226.126.025.325.525.325.524.424.524.725.924.824.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax26.826.226.126.025.325.525.325.524.424.524.725.924.824.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Commercial100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Industrial


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
Value163180158145137183201196208246212192199237
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.112.013.716.914.812.014.822.121.513.414.822.520.313.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax17.112.013.716.914.812.014.822.121.513.414.822.520.313.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Industrial100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Misc.


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
Value6.51411149.01817131924189.51524
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.70.91.01.61.01.21.31.52.01.31.31.11.51.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.70.91.01.61.01.21.31.52.01.31.31.11.51.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Misc.100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Offsystem


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
Value17148.2999999999999976.08.0181716232028202022
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.00.70.70.91.21.31.92.41.12.02.42.11.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.00.70.70.91.21.31.92.41.12.02.42.11.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Offsystem100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Residential


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
Value51090267347154291577843748010948224115021008
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax53.659.958.454.858.160.057.349.049.659.657.248.151.258.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax53.659.958.454.858.160.057.349.049.659.657.248.151.258.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Residential100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

nix:Commercial, nix:ElectricOperations


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
Value130122114132112120115136115119118140116116
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.68.210.015.412.17.98.515.311.96.58.316.411.96.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.68.210.015.412.17.98.515.311.96.58.316.411.96.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Commercial nix:ElectricOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Commercial, nix:GasDistributionOperations


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
Value125271186911222692289012133023580127308
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.218.016.210.713.217.716.810.212.618.016.49.512.918.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.218.016.210.713.217.716.810.212.618.016.49.512.918.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Commercial nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Industrial, nix:ElectricOperations


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
Value11912211110289109137151155163145153152162
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.58.29.611.99.67.110.117.016.18.910.117.915.59.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.58.29.611.99.67.110.117.016.18.910.117.915.59.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Industrial nix:ElectricOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Industrial, nix:GasDistributionOperations


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
Value4457474248746445528266394774
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.63.84.15.05.24.94.75.15.54.54.64.64.94.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax4.63.84.15.05.24.94.75.15.54.54.64.64.94.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Industrial nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Misc., nix:ElectricOperations


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
Value1.44.23.59999999999999837.23.55.94.83.16.76.95.10.14.77.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.30.30.80.40.40.40.30.70.40.40.00.50.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.10.30.30.80.40.40.40.30.70.40.40.00.50.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Misc. nix:ElectricOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Misc., nix:GasDistributionOperations


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
Value4.99.98.1000000000000036.85.312129.81217139.21016
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.70.70.80.60.80.91.11.30.90.91.11.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.50.70.70.80.60.80.91.11.30.90.91.11.01.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Misc. nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Misc., us-gaap:CorporateAndOther


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
Value0.20.20.20.20.20.20.20.20.20.20.10.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Misc. us-gaap:CorporateAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Offsystem, nix:GasDistributionOperations


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
Value17148.2999999999999976.08.0181716232028202022
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.00.70.70.91.21.31.92.41.12.02.42.11.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax1.81.00.70.70.91.21.31.92.41.12.02.42.11.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Offsystem nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Residential, nix:ElectricOperations


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
Value131129116164127119108148105118112154113114
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.88.610.119.113.77.88.016.710.96.57.818.111.56.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.88.610.119.113.77.88.016.710.96.57.818.111.56.7
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Residential nix:ElectricOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:Residential, nix:GasDistributionOperations


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
Value378773556306414796670288375975709257389893
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.851.348.335.644.552.249.332.438.753.249.430.039.752.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax39.851.348.335.644.552.249.332.438.753.249.430.039.752.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:Residential nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:StatementBusinessSegments

nix:ElectricOperations


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
Value382379345407333354366439383408381449386401
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax40.125.230.047.235.723.226.949.339.622.326.652.539.323.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax40.125.230.047.235.723.226.949.339.622.326.652.539.323.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:GasDistributionOperations


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
Value56911278074545991171992451585142610544065951315
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax59.874.870.052.764.376.873.050.660.477.773.447.560.676.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax59.874.870.052.764.376.873.050.660.477.773.447.560.676.6
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CorporateAndOther


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
Value0.20.20.20.20.20.20.20.20.20.20.10.20.20.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value98615451002902962160512419311010186913388951007175013689179901598129786189714361097817116921491691112313352320159610761212178214109561038165814901068122822321752113811712358
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 RevenueFromContractWithCustomerExcludingAssessedTax103.5102.686.9104.8103.2105.291.4104.5104.3101.993.2104.6102.5102.0100.0103.8100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Revenues us-gaap:StatementBusinessSegments

nix:ElectricOperations


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value403402370432356377393467406431403476405423420486
Percentage of Revenues40.926.136.947.937.023.531.750.240.223.130.153.240.224.230.753.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.426.732.150.238.224.729.052.542.023.528.155.741.224.730.755.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations105.6106.2107.1106.2107.0106.5107.6106.4106.0105.6105.7106.1104.8105.50.00.0

nix:GasDistributionOperations


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value577113882647360912311006466607144210614216051330951434
Percentage of Revenues58.573.782.552.463.376.781.150.160.177.179.347.160.176.069.547.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax60.675.671.754.965.380.774.152.462.678.673.949.361.677.569.549.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations101.3101.0102.4104.1101.7105.1101.4103.5103.7101.1100.7103.8101.6101.10.00.0

us-gaap:CorporateAndOther


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value1251111391201001061261171141111711161161141431261211201181041021021129812013014314013012813912212213-315.91211232.2
Percentage of Revenues12.77.213.913.410.56.710.212.611.36.012.813.011.56.510.513.812.37.59.112.111.47.110.312.010.36.18.512.59.85.58.811.310.10.8-22.412.711.90.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax13.27.412.114.010.87.09.313.111.86.111.913.611.86.710.514.312.37.59.112.111.47.110.312.010.36.18.512.59.85.58.811.310.10.8-22.412.711.90.1
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther62800.055600.069500.060350.050450.053450.063050.058550.057200.055650.0171100.058300.058150.057150.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:IntersegmentElimination


Revenuesus-gaap:
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value-123.6-103.9-109.9-129.3-120.4-117.7-114.6-174.5-119.9-119.5-117.6-146.9-130.1-125.5-123.3-118.2-104.0-102.1-102.2-108.5-94.4-151.5-172.6-185.5-170.3-161.3-169.6-180.3-151.1-141.7-165.1-172.9-151.1-147.1
Percentage of Revenues-13.7-10.8-6.8-10.4-12.9-11.6-6.1-13.0-13.4-11.9-6.7-10.7-14.2-12.7-7.7-9.1-12.1-11.4-7.1-9.9-11.6-13.0-8.0-11.0-15.2-12.1-7.3-11.3-14.0-11.7-9.3-12.3-15.8-14.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-14.3-11.1-7.2-9.5-13.5-12.1-6.2-12.2-14.0-12.2-6.8-10.7-14.7-12.7-7.7-9.1-12.1-11.4-7.1-9.9-11.6-13.0-8.0-11.0-15.2-12.1-7.3-11.3-14.0-11.7-9.3-12.3-15.8-14.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:StatementBusinessSegments, us-gaap:Subsegments

nix:ElectricOperations, nix:Intersegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value0.20.20.20.10.20.20.20.20.20.20.20.20.20.20.20.2
Percentage of Revenues0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations nix:Intersegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

nix:ElectricOperations, nix:Unaffiliated


Revenuesus-gaap:
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value403402432356377467406430476404423485
Percentage of Revenues40.926.047.937.023.550.240.223.053.240.224.253.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax42.426.750.238.224.752.541.923.555.641.224.755.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:ElectricOperations nix:Unaffiliated0.00.00.00.00.00.00.00.00.00.00.00.0

nix:GasDistributionOperations, nix:Intersegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value3.03.13.13.03.03.03.23.33.33.33.33.33.23.33.63.5
Percentage of Revenues0.30.20.30.30.30.20.30.40.30.20.20.40.30.20.30.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.30.20.30.30.30.20.20.40.30.20.20.40.30.20.30.4
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations nix:Intersegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

nix:GasDistributionOperations, nix:Unaffiliated


Revenuesus-gaap:
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value5741135470606122846360314384186011327431
Percentage of Revenues58.273.552.163.076.549.859.876.946.859.875.847.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax60.375.454.665.080.552.062.378.448.961.377.348.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax nix:GasDistributionOperations nix:Unaffiliated0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CorporateAndOther, nix:Intersegment


Revenuesus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value117103121120100106125116114111171116116114143126
Percentage of Revenues11.96.712.213.410.56.610.112.511.35.912.813.011.56.510.513.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax12.36.910.614.010.87.09.313.111.86.111.913.611.86.610.514.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther nix:Intersegment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CorporateAndOther, nix:Unaffiliated


Revenuesus-gaap:
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-30
Value8.27.30.20.20.20.20.20.20.20.20.20.1
Percentage of Revenues0.80.50.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax0.90.50.00.00.00.00.00.00.00.00.00.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:CorporateAndOther nix:Unaffiliated0.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:Revenues us-gaap:Subsegments

us-gaap:IntersegmentElimination


Revenuesus-gaap:
Period End2021-06-302021-03-312020-06-302020-03-31
Value-120.6-107.2-103.9-109.9
Percentage of Revenues-12.2-6.9-10.8-6.8
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-12.7-7.1-11.1-7.2
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:IntersegmentElimination0.00.00.00.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2231322194220402270122436225922265922132219742188921804206992030720098199611926918822186351869118067176171747117492170552560624898248662371023257231072265322084216212163621844208382040920445207081974219346194781993819271
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets dei:LegalEntity

nix:Rosewater


Assetsdei:
Period End2021-06-302021-03-312020-12-31
Value177178177
Percentage of Assets0.80.80.8
Percentage of Assets0.80.80.8
Percentage of Assets nix:Rosewater100.0100.0100.0

us-gaap:Assets us-gaap:StatementBusinessSegments

nix:ElectricOperations


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value64436027573554785233
Percentage of Assets29.226.626.327.428.0
Percentage of Assets29.226.626.327.428.0
Percentage of Assets nix:ElectricOperations100.0100.0100.0100.0100.0

nix:GasDistributionOperations


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1343314224135271204811096
Percentage of Assets60.962.862.060.459.4
Percentage of Assets60.962.862.060.459.4
Percentage of Assets nix:GasDistributionOperations100.0100.0100.0100.0100.0

us-gaap:CorporateAndOther


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value21642407254124342362213243464323401347194407
Percentage of Assets9.810.611.712.212.612.217.519.118.422.822.1
Percentage of Assets9.810.611.712.212.612.217.519.118.422.822.1
Percentage of Assets us-gaap:CorporateAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Liabilities

us-gaap:Liabilities dei:LegalEntity

us-gaap:Liabilities

nix:Rosewater


Liabilitiesdei:
Period End2021-06-302021-03-312020-12-31
Value8.48.420
Percentage of Liabilities100.0100.0100.0
Percentage of Assets0.00.00.1
Percentage of Assets nix:Rosewater4.74.711.8

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2231322194220402270122436225922265922132219742188921804206992030720098199611926918822186351869118067176171747117492170552560624898248662371023257231072265322084216212163621844208382040920445207081974219346194781993819271
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value6523593157525424566157415986584859765779575050735463450643204363412241914071381138103872384338006505652361756007602860125886570057025690555454105105508049974990500350144923485447285076
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets29.226.726.123.925.225.426.426.427.226.426.424.526.922.421.622.621.922.521.821.121.622.222.022.325.426.224.825.325.926.026.025.826.426.325.426.025.024.824.125.325.925.724.725.20.00.0

us-gaap:StockholdersEquity us-gaap:StatementClassOfStock, us-gaap:StatementEquityComponents

us-gaap:SeriesCPreferredStock, us-gaap:PreferredStock


Stockholders
Period End2021-06-30
Value838
Percentage of StockholdersEquity12.9
Percentage of Assets3.8
Percentage of Assets us-gaap:SeriesCPreferredStock us-gaap:PreferredStock0.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-193.6-221.9-230.6-92.6-130.3-80.8-52.8-37.22.5-20.9-19.0-43.4-43.7-35.6-19.6-25.1-35.1-50.6-41.6-41.4-42.5-43.6-65.5-59.7-57.9-45.9-172.011
Percentage of StockholdersEquity-3.6-3.9-4.0-1.5-2.2-1.4-0.9-0.60.0-0.4-0.4-1.0-1.0-0.9-0.5-0.6-0.9-0.8-0.7-0.7-0.7-0.7-1.2-1.2-1.2-0.9-3.60.2
Percentage of Assets-0.9-1.0-1.0-0.4-0.6-0.4-0.2-0.20.0-0.1-0.1-0.2-0.2-0.2-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.3-0.3-0.3-0.20.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value6684667666716666642664176406640361616151554055295518522551745153507847874764473447154690459741674103405740204011
Percentage of StockholdersEquity123.2117.9116.2111.4109.9107.4110.8111.3121.4112.6123.0128.0126.5126.7123.5126.6132.177.579.378.578.479.782.883.483.483.685.079.0
Percentage of Assets29.429.829.529.429.029.229.329.429.830.327.627.728.627.827.827.629.019.320.120.420.420.721.020.120.621.10.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value3.83.83.83.83.83.83.83.83.73.73.43.43.43.33.33.33.23.23.23.23.23.23.12.82.82.82.72.7
Percentage of StockholdersEquity0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PreferredStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value8808808808808808808808803933940.00.00.0
Percentage of StockholdersEquity16.215.515.314.715.014.715.215.37.87.20.00.00.0
Percentage of Assets3.93.93.93.94.04.04.04.01.91.90.00.00.0
Percentage of Assets us-gaap:PreferredStock0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-1849.6-1576.7-1483.4-1370.8-1231.6-1144.0-1358.0-1399.3-1387.5-965.5-919.2-1073.1-1020.6-975.6-874.2-972.2-1123.31494133913901394128510599179018659011074
Percentage of StockholdersEquity-34.1-27.8-25.8-22.9-21.1-19.1-23.5-24.3-27.3-17.7-20.4-24.8-23.4-23.7-20.9-23.9-29.224.222.323.123.221.819.118.318.317.819.121.2
Percentage of Assets-8.1-7.0-6.6-6.0-5.6-5.2-6.2-6.4-6.7-4.8-4.6-5.4-5.3-5.2-4.7-5.2-6.46.05.76.06.05.74.94.44.54.50.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.5-95.9-94.6-94.6-93.1-88.7-79.3-58.9-58.9-58.8-58.6-48.6-40.5-30.5-27.4-25.9-23.3-23.3
Percentage of StockholdersEquity-1.8-1.8-1.7-1.7-1.7-1.7-1.7-1.7-2.0-1.8-2.2-2.2-2.2-2.3-2.2-2.2-2.1-1.0-1.0-1.0-1.0-0.8-0.7-0.6-0.6-0.5-0.5-0.5
Percentage of Assets-0.4-0.4-0.4-0.4-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.2-0.2-0.3-0.3-0.2-0.2-0.1-0.1-0.10.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value13841593165928202859322518531378157819152055136913151633176313321280147117621378125913951577163723352261246620112054232021591745170720312352183817511970224818601745198524482223
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.27.27.512.412.714.38.26.27.28.89.46.66.58.18.86.96.87.99.47.67.18.09.09.69.19.19.98.58.810.09.57.97.99.410.88.88.69.610.99.49.010.212.311.5

us-gaap:AssetsCurrent dei:LegalEntity

nix:Rosewater


Assets
Period End2021-06-302021-03-312020-12-31
Value4.84.21.7
Percentage of AssetsCurrent0.30.30.1
Percentage of Assets0.00.00.0
Percentage of Assets nix:Rosewater2.72.41.0

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
Value778911658142203139282315111241683529191728261615231531496422517183826144410136125238112259629.2107.4110162034
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 Assets0.30.40.50.30.60.90.60.10.10.70.50.20.30.20.10.10.10.20.10.10.10.10.10.21.90.20.10.10.10.20.10.10.20.50.20.10.30.20.10.10.30.30.00.00.00.00.10.00.0

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-31
Value909612567153213148373216012153814438283239364549
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.40.60.30.70.90.70.20.10.70.60.30.40.20.20.10.20.20.20.30.2

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value563794791521545716856539870113210585005849738984805458138474714746476605006721152107063982412711005591716107090752655373085451263810631079808
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.53.63.62.32.43.23.82.44.05.24.92.42.94.84.52.52.94.44.52.62.73.73.82.92.64.64.32.73.55.54.42.73.34.94.22.52.73.64.12.63.35.55.44.2

Inventory Raw Materials And Supplies

us-gaap:InventoryRawMaterialsAndSupplies

us-gaap:InventoryRawMaterialsAndSupplies


Inventory
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1431451411271311301201151111071019799104105102969710110010294868411210910610610610410199114111979999898787878483102
Percentage of InventoryRawMaterialsAndSupplies100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.60.70.60.60.60.60.50.50.50.50.50.50.50.50.50.50.50.50.50.60.60.50.50.50.40.40.40.40.50.50.40.50.50.50.40.50.50.40.40.40.40.40.40.5

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value1871098611214218214985103144129891091551326591139130648913310775133187169103320321330246224228357280274277261119100119120126
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.80.50.40.50.60.80.70.40.50.70.60.40.50.80.70.30.50.70.70.40.50.80.60.40.50.80.70.41.41.41.51.11.01.11.61.31.31.41.30.60.50.60.60.7

Property Plant And Equipment Gross

us-gaap:PropertyPlantAndEquipmentGross

us-gaap:PropertyPlantAndEquipmentGross


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
Value2417924541228192164920049189882564223664219402051819633
Percentage of PropertyPlantAndEquipmentGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets109.7108.3104.7108.5107.3108.5103.1104.5100.499.198.5

us-gaap:PropertyPlantAndEquipmentGross us-gaap:PropertyPlantAndEquipmentByType

nix:CommonUtility


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value197153155141
Percentage of PropertyPlantAndEquipmentGross0.80.60.70.7
Percentage of Assets0.90.70.70.7
Percentage of Assets nix:CommonUtility0.00.00.00.0

nix:ConstructionWorkInProcess


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value572457474950
Percentage of PropertyPlantAndEquipmentGross2.41.92.14.4
Percentage of Assets2.62.02.24.8
Percentage of Assets nix:ConstructionWorkInProcess0.00.00.00.0

nix:ElectricUtility


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value6478890283747403
Percentage of PropertyPlantAndEquipmentGross26.836.336.734.2
Percentage of Assets29.439.338.437.1
Percentage of Assets nix:ElectricUtility0.00.00.00.0

nix:GasDistributionUtility


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value14010149891377612531
Percentage of PropertyPlantAndEquipmentGross57.961.160.457.9
Percentage of Assets63.666.263.262.8
Percentage of Assets nix:GasDistributionUtility0.00.00.00.0

nix:NonUtilityAndOther


Property
Period End2020-12-312019-12-312018-12-312017-12-31
Value27463938623
Percentage of PropertyPlantAndEquipmentGross11.40.20.22.9
Percentage of Assets12.50.20.23.1
Percentage of Assets nix:NonUtilityAndOther0.00.00.00.0

nix:RenewableGenerationAssets


Property
Period End2020-12-31
Value175
Percentage of PropertyPlantAndEquipmentGross0.7
Percentage of Assets0.8
Percentage of Assets nix:RenewableGenerationAssets0.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312011-03-312010-12-312009-12-31
Value7560762972777290698168769625929990258718852884928387
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets34.333.733.436.537.439.338.741.041.342.143.842.643.5

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PropertyPlantAndEquipmentByType

nix:CommonUtility


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-31
Value109797452
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment1.41.01.00.7
Percentage of Assets0.50.40.30.3
Percentage of Assets nix:CommonUtility0.00.00.00.0

nix:ElectricUtility


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-31
Value2305397338093673
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment30.552.152.350.4
Percentage of Assets10.517.517.518.4
Percentage of Assets nix:ElectricUtility0.00.00.00.0

nix:GasDistributionUtility


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-31
Value3292355633733227
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment43.646.646.444.3
Percentage of Assets14.915.715.516.2
Percentage of Assets nix:GasDistributionUtility0.00.00.00.0

nix:NonUtilityAndOther


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-31
Value18532019336
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment24.50.30.34.6
Percentage of Assets8.40.10.11.7
Percentage of Assets nix:NonUtilityAndOther0.00.00.00.0

nix:RenewableGenerationAssets


Accumulated
Period End2020-12-31
Value0.1
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment0.0
Percentage of Assets0.0
Percentage of Assets nix:RenewableGenerationAssets0.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312011-03-312010-12-312009-12-31
Value16619169121554214359130681211116017143651291511800111401109710688
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets75.474.671.371.969.969.264.463.459.157.057.255.755.5

us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity

nix:Rosewater


Property
Period End2021-06-302021-03-312020-12-31
Value172174175
Percentage of PropertyPlantAndEquipmentNet0.00.01.1
Percentage of Assets0.80.80.8
Percentage of Assets nix:Rosewater97.397.699.0

Investments In Affiliates Subsidiaries Associates And Joint Ventures

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures

us-gaap:InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures


Investments
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value0.91.41.31.32.22.32.12.12.64.25.05.55.66.06.56.66.56.76.76.96.7452447452443437407373327279260243215211204204200197202200165
Percentage of InvestmentsInAffiliatesSubsidiariesAssociatesAndJointVentures100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.01.81.81.81.91.91.81.61.51.31.21.11.01.01.01.01.01.01.01.00.9

Goodwill

us-gaap:Goodwill

us-gaap:Goodwill


Goodwill
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value14851485148514851485148514851690169016901690169016901690169016901690169016901690169016901690169036663666366636663666366636663666366636663677367736773677367736773677367736773677
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.76.76.76.56.66.66.67.67.77.77.88.28.38.48.58.89.09.19.09.49.69.79.79.914.314.714.715.515.815.916.216.617.016.916.817.618.018.017.818.619.018.918.419.1

us-gaap:Goodwill us-gaap:StatementBusinessSegments

nix:GasDistributionOperations


Goodwillus-gaap:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value148514851485148514851485148516901690169016901690
Percentage of Goodwill100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.76.76.76.56.66.66.67.67.77.77.88.2
Percentage of Assets nix:GasDistributionOperations0.00.011.10.00.00.010.40.00.00.012.50.0

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OperatingLeaseRightOfUseAsset


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312019-01-01
Value396460595357
Percentage of OperatingLeaseRightOfUseAsset100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.30.30.30.20.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value35233514350935633575356836634053404440224000393839403801362936813671367536613627360436073609352457095697571954565475551955515896597160346138604561406212630459665955601160446050
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets15.815.815.915.715.915.816.218.318.418.418.319.019.418.918.219.119.519.719.620.120.520.620.620.722.322.923.023.023.523.924.526.727.627.928.129.030.130.430.430.230.830.930.331.4

Accounts Payable Current

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value480554589410402505666494552675883433455497625447451461539352371392433349429563670427459714619369393527538300292380434244316429581502
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.22.52.71.81.82.22.92.22.53.14.12.12.22.53.12.32.42.52.91.92.12.22.52.01.72.32.71.82.03.12.71.71.82.42.51.41.41.92.11.21.62.22.92.6

Contract With Customer Liability Current

us-gaap:ContractWithCustomerLiabilityCurrent

us-gaap:ContractWithCustomerLiabilityCurrent


Contract
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value148146243229163163256
Percentage of ContractWithCustomerLiabilityCurrent100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.70.71.11.00.70.71.1

Dividends Payable Current

us-gaap:DividendsPayableCurrent

us-gaap:DividendsPayableCurrent


Dividends
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value941059988999482948270650.05857560.05353490.049820.08282780.07878740.074680.06464640.10.2
Percentage of DividendsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.40.40.40.40.40.40.40.30.30.00.30.30.30.00.30.30.30.00.30.30.00.30.40.30.00.40.40.30.00.40.30.00.30.30.30.00.0

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value17062258227934463227416137453339381340154036341125603226317825662778366434522911269624952657207325242758395430483431334031783005206829743301272726623718364628872558309636493149
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.610.210.315.214.418.416.515.117.418.318.516.512.616.115.913.314.819.718.516.115.314.315.212.29.911.115.912.914.814.514.013.69.613.715.113.113.018.217.614.613.215.918.316.3

us-gaap:LiabilitiesCurrent dei:LegalEntity

nix:Rosewater


Liabilities
Period End2021-06-302021-03-312020-12-31
Value2.72.815
Percentage of LiabilitiesCurrent0.20.10.7
Percentage of Assets0.00.00.1
Percentage of Assets nix:Rosewater1.51.68.6

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OperatingLeaseLiabilityCurrent


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value1013109.49.3
Percentage of OperatingLeaseLiabilityCurrent100.0100.0100.0100.0100.0
Percentage of Assets0.00.10.00.00.0

us-gaap:OperatingLeaseLiabilityCurrent nix:LeaseType

nix:OperatingLeaseMember


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value1013109.49.3
Percentage of OperatingLeaseLiabilityCurrent100.0100.0100.0100.0100.0
Percentage of Assets0.00.10.00.00.0
Percentage of Assets nix:OperatingLeaseMember0.00.00.00.00.0

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value2621641131191401801441208679585475109901197876826768103114121313317378408347323327308283269309232219239301254230249336310
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.20.70.50.50.60.80.60.50.40.40.30.30.40.50.50.60.40.40.40.40.40.60.70.71.21.31.51.71.51.41.41.41.31.21.41.11.11.21.51.31.21.31.71.6

Taxes Payable Current

us-gaap:TaxesPayableCurrent

us-gaap:TaxesPayableCurrent


Taxes
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value232301244147195223231157167232222150165212208148152216195130140203183137221287266189216278254181202258235172185237220157179244221212
Percentage of TaxesPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.01.41.10.60.91.01.00.70.81.11.00.70.81.11.00.80.81.21.00.70.81.21.00.80.91.21.10.80.91.21.10.80.91.21.10.80.91.21.10.80.91.31.11.1

Liabilities Noncurrent

us-gaap:LiabilitiesNoncurrent

us-gaap:LiabilitiesNoncurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value47914707470346204736487150715090507449854910512051925079495148215144519051105247525351975043504867456712658062566157611559956288623461676169588158345812579755275444544054305298
Percentage of LiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets21.521.221.320.421.121.622.423.023.122.822.524.725.625.324.825.027.327.827.329.029.829.728.829.626.327.026.526.426.526.526.528.528.828.528.228.228.628.428.028.028.127.927.227.5

Long Term Debt And Capital Lease Obligations

us-gaap:LongTermDebtAndCapitalLeaseObligations

us-gaap:LongTermDebtAndCapitalLeaseObligations


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value92019202921992088810781778567853710971107105709470927286751275186777559060586096585759055948613388817957815583977640763875937089761668036819681968065834626763376340592759365969
Percentage of LongTermDebtAndCapitalLeaseObligations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets41.241.541.840.639.334.634.735.532.432.532.634.334.936.337.639.036.030.032.433.733.233.834.036.034.732.032.835.432.933.133.532.135.231.431.232.733.428.530.332.132.830.429.831.0

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value1587157314701439147714511485
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets7.17.16.76.36.66.46.6

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-31
Value303314275293296299250-259.3-461.8-466.9
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.41.41.31.51.61.71.0-1.1-2.1-2.3

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanType

us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value295411039412
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent9.617.440.213.5138.8
Percentage of Assets0.10.20.50.22.2
Percentage of Assets us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.0

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312015-06-302015-03-312014-12-31
Value9094859509460.0
Percentage of MinorityInterest100.0100.0100.0100.0100.00.0
Percentage of Assets0.40.40.43.73.80.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value566444286214198187218224222218177215184191194187188199200182187188208186270294291297224219216219216225226246242247244193157163162152
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.52.01.30.90.90.81.01.01.01.00.81.00.91.01.01.01.01.11.11.01.11.11.21.11.11.21.21.31.00.91.01.01.01.01.01.21.21.21.21.00.80.80.80.8

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value2951504944
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.20.2

us-gaap:OperatingLeaseLiabilityNoncurrent nix:LeaseType

nix:OperatingLeaseMember


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value2951504944
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0100.0100.0100.0
Percentage of Assets0.10.20.20.20.2
Percentage of Assets nix:OperatingLeaseMember0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-312019-12-31
Value5.29.4
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0100.0
Percentage of Assets0.00.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo nix:LeaseType

nix:FleetLease


Lessee
Period End2020-12-312019-12-31
Value2728
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo532.7301.1
Percentage of Assets0.10.1
Percentage of Assets nix:FleetLease0.00.0

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value5.29.4
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0100.0
Percentage of Assets0.00.0
Percentage of Assets nix:OperatingLeaseMember0.00.0

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-312019-12-31
Value4.78.2
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0100.0
Percentage of Assets0.00.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree nix:LeaseType

nix:FleetLease


Lessee
Period End2020-12-312019-12-31
Value2423
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree529.8285.4
Percentage of Assets0.10.1
Percentage of Assets nix:FleetLease0.00.0

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value4.78.2
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0100.0
Percentage of Assets0.00.0
Percentage of Assets nix:OperatingLeaseMember0.00.0

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-312019-12-31
Value4.57.6
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0100.0
Percentage of Assets0.00.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour nix:LeaseType

nix:FleetLease


Lessee
Period End2020-12-312019-12-31
Value2219
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour488.9261.8
Percentage of Assets0.10.1
Percentage of Assets nix:FleetLease0.00.0

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value4.57.6
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0100.0
Percentage of Assets0.00.0
Percentage of Assets nix:OperatingLeaseMember0.00.0

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-312019-12-31
Value3.76.6
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0100.0
Percentage of Assets0.00.0

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive nix:LeaseType

nix:FleetLease


Lessee
Period End2020-12-312019-12-31
Value1915
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive513.5230.3
Percentage of Assets0.10.1
Percentage of Assets nix:FleetLease0.00.0

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value3.76.6
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0100.0
Percentage of Assets0.00.0
Percentage of Assets nix:OperatingLeaseMember0.00.0

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-312019-12-31
Value1831
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0100.0
Percentage of Assets0.10.1

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive nix:LeaseType

nix:FleetLease


Lessee
Period End2020-12-312019-12-31
Value2115
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive118.147.9
Percentage of Assets0.10.1
Percentage of Assets nix:FleetLease0.00.0

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value1831
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0100.0
Percentage of Assets0.10.1
Percentage of Assets nix:OperatingLeaseMember0.00.0

Operating Lease Liability

us-gaap:OperatingLeaseLiability nix:LeaseType

us-gaap:OperatingLeaseLiability

nix:OperatingLeaseMember


Operating
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value4064615853
Percentage of OperatingLeaseLiability100.0100.0100.0100.0100.0
Percentage of Assets0.20.30.30.30.2
Percentage of Assets nix:OperatingLeaseMember0.00.00.00.00.0

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-312019-12-31
Value4879
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0
Percentage of Assets0.20.3

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue nix:LeaseType

nix:OperatingLeaseMember


Lessee
Period End2020-12-312019-12-31
Value4879
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0100.0
Percentage of Assets0.20.3
Percentage of Assets nix:OperatingLeaseMember0.00.0

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount nix:LeaseType

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

nix:OperatingLeaseMember


Lessee
Period End2020-12-31
Value7800000.0
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0
Percentage of Assets0.0
Percentage of Assets nix:OperatingLeaseMember0.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-312008-12-312007-12-31
Value6523593157525424566157415986584859765779575050735463450643204363412241914071381138103872384338006505652361756007602860125886570057025690555454105105508049974990500350144923485447285076
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets29.226.726.123.925.225.426.426.427.226.426.424.526.922.421.622.621.922.521.821.121.622.222.022.325.426.224.825.325.926.026.025.826.426.325.426.025.024.824.125.325.925.724.725.20.00.0

us-gaap:StockholdersEquity us-gaap:StatementClassOfStock, us-gaap:StatementEquityComponents

us-gaap:SeriesCPreferredStock, us-gaap:PreferredStock


Stockholders
Period End2021-06-30
Value838
Percentage of StockholdersEquity12.9
Percentage of Assets3.8
Percentage of Assets us-gaap:SeriesCPreferredStock us-gaap:PreferredStock0.0

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-193.6-221.9-230.6-92.6-130.3-80.8-52.8-37.22.5-20.9-19.0-43.4-43.7-35.6-19.6-25.1-35.1-50.6-41.6-41.4-42.5-43.6-65.5-59.7-57.9-45.9-172.011
Percentage of StockholdersEquity-3.6-3.9-4.0-1.5-2.2-1.4-0.9-0.60.0-0.4-0.4-1.0-1.0-0.9-0.5-0.6-0.9-0.8-0.7-0.7-0.7-0.7-1.2-1.2-1.2-0.9-3.60.2
Percentage of Assets-0.9-1.0-1.0-0.4-0.6-0.4-0.2-0.20.0-0.1-0.1-0.2-0.2-0.2-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.3-0.3-0.3-0.20.00.0
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value6684667666716666642664176406640361616151554055295518522551745153507847874764473447154690459741674103405740204011
Percentage of StockholdersEquity123.2117.9116.2111.4109.9107.4110.8111.3121.4112.6123.0128.0126.5126.7123.5126.6132.177.579.378.578.479.782.883.483.483.685.079.0
Percentage of Assets29.429.829.529.429.029.229.329.429.830.327.627.728.627.827.827.629.019.320.120.420.420.721.020.120.621.10.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value3.83.83.83.83.83.83.83.83.73.73.43.43.43.33.33.33.23.23.23.23.23.23.12.82.82.82.72.7
Percentage of StockholdersEquity0.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:PreferredStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312016-12-31
Value8808808808808808808808803933940.00.00.0
Percentage of StockholdersEquity16.215.515.314.715.014.715.215.37.87.20.00.00.0
Percentage of Assets3.93.93.93.94.04.04.04.01.91.90.00.00.0
Percentage of Assets us-gaap:PreferredStock0.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-1849.6-1576.7-1483.4-1370.8-1231.6-1144.0-1358.0-1399.3-1387.5-965.5-919.2-1073.1-1020.6-975.6-874.2-972.2-1123.31494133913901394128510599179018659011074
Percentage of StockholdersEquity-34.1-27.8-25.8-22.9-21.1-19.1-23.5-24.3-27.3-17.7-20.4-24.8-23.4-23.7-20.9-23.9-29.224.222.323.123.221.819.118.318.317.819.121.2
Percentage of Assets-8.1-7.0-6.6-6.0-5.6-5.2-6.2-6.4-6.7-4.8-4.6-5.4-5.3-5.2-4.7-5.2-6.46.05.76.06.05.74.94.44.54.50.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-312007-12-31
Value-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.9-99.5-95.9-94.6-94.6-93.1-88.7-79.3-58.9-58.9-58.8-58.6-48.6-40.5-30.5-27.4-25.9-23.3-23.3
Percentage of StockholdersEquity-1.8-1.8-1.7-1.7-1.7-1.7-1.7-1.7-2.0-1.8-2.2-2.2-2.2-2.3-2.2-2.2-2.1-1.0-1.0-1.0-1.0-0.8-0.7-0.6-0.6-0.5-0.5-0.5
Percentage of Assets-0.4-0.4-0.4-0.4-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.2-0.2-0.3-0.3-0.2-0.2-0.1-0.1-0.10.00.0
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value6613602558375661574159865750432038113810387238433800745574696175
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets29.627.126.525.225.426.426.421.621.121.622.222.022.329.130.024.8

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value-123.6-75.5-156.7-221.9-230.6-92.6-37.2-43.4-179.0-156.3-103.8-35.1-19.6-44.4-46.6-50.6
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-1.9-1.3-2.7-3.9-4.0-1.5-0.6-1.0-4.7-4.1-2.7-0.9-0.5-0.6-0.6-0.8
Percentage of Assets-0.6-0.3-0.7-1.0-1.0-0.4-0.2-0.2-1.0-0.9-0.6-0.2-0.1-0.2-0.2-0.2
Percentage of Assets us-gaap:AccumulatedOtherComprehensiveIncome0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value6728689268906676667166666403552951355118510250785078506550484787
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest101.7114.4118.0117.9116.2111.4111.3128.0134.7134.3131.8132.1133.667.967.677.5
Percentage of Assets30.231.131.329.829.529.429.427.728.429.129.229.029.819.820.319.3
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value3.93.93.93.83.83.83.83.43.33.23.23.23.23.23.23.2
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest0.10.10.10.10.10.10.10.10.10.10.10.10.10.00.00.1
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312015-06-302015-03-312014-12-31
Value9094859509460.0
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest1.41.61.512.712.70.0
Percentage of Assets0.40.40.43.73.80.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.00.00.00.0

us-gaap:PreferredStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-31
Value1718880880880880880880
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest26.014.615.115.515.314.715.3
Percentage of Assets7.74.04.03.93.93.94.0
Percentage of Assets us-gaap:PreferredStock0.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value-1704.1-1669.8-1765.2-1576.7-1483.4-1370.8-1399.3-1073.1-1060.9-1067.4-1042.9-1123.3-1182.7156115971494
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-25.8-27.7-30.2-27.8-25.8-22.9-24.3-24.8-27.8-28.0-26.9-29.2-31.120.921.424.2
Percentage of Assets-7.6-7.5-8.0-7.0-6.6-6.0-6.4-5.4-5.9-6.1-6.0-6.4-6.96.16.46.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:TreasuryStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-06-302020-03-312019-12-312018-12-312017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value-99.9-99.9-99.9-99.9-99.9-99.9-99.9-95.9-87.4-87.2-86.7-79.3-79.2-79.1-79.0-58.9
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest-1.5-1.7-1.7-1.8-1.7-1.7-1.7-2.2-2.3-2.3-2.2-2.1-2.1-1.1-1.1-1.0
Percentage of Assets-0.4-0.5-0.5-0.4-0.4-0.4-0.5-0.5-0.5-0.5-0.5-0.5-0.5-0.3-0.3-0.2
Percentage of Assets us-gaap:TreasuryStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value3900000.03900000.03900000.03800000.03800000.03800000.03800000.03800000.03800000.03800000.03800000.03700000.03700000.03400000.03400000.03400000.03300000.03300000.03300000.03300000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03200000.03100000.03100000.03100000.03100000.02900000.02900000.02800000.02800000.02800000.02800000.02800000.02800000.0
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Additional Paid In Capital Common Stock

us-gaap:AdditionalPaidInCapitalCommonStock

us-gaap:AdditionalPaidInCapitalCommonStock


Additional
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value67286892689066846676667166666426641764066403616161515540552955185225517451535135511851025078507850655048478747644734471546904672464646274597457942214198416741494132412041034057
Percentage of AdditionalPaidInCapitalCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets30.231.131.329.429.829.529.429.029.229.329.429.830.327.627.728.627.827.827.628.429.129.229.029.819.820.319.320.120.420.420.721.221.521.421.022.020.720.520.121.021.421.220.621.1

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-1704.1-1669.8-1765.2-1849.6-1576.7-1483.4-1370.8-1231.6-1144.0-1358.0-1399.3-1387.5-965.5-919.2-1073.1-1020.6-975.6-874.2-972.2-1060.9-1067.4-1042.9-1123.3-1182.715611597149413391390139412851133116411701059925980980917922952978901865
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-7.6-7.5-8.0-8.1-7.0-6.6-6.0-5.6-5.2-6.2-6.4-6.7-4.8-4.6-5.4-5.3-5.2-4.7-5.2-5.9-6.1-6.0-6.4-6.96.16.46.05.76.06.05.75.15.45.44.94.44.84.84.44.74.95.04.54.5

Accumulated Other Comprehensive Income Loss Net Of Tax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value-123.6-75.5-156.7-193.6-221.9-230.6-92.6-130.3-80.8-52.8-37.22.5-20.9-19.0-43.4-43.7-35.6-19.6-25.1-179.0-156.3-103.8-35.1-19.6-44.4-46.6-50.6-41.6-41.4-42.5-43.6-60.4-62.0-62.3-65.5-56.8-59.0-60.9-59.7-54.4-54.5-56.7-57.9-45.9
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets-0.6-0.3-0.7-0.9-1.0-1.0-0.4-0.6-0.4-0.2-0.20.0-0.1-0.1-0.2-0.2-0.2-0.1-0.1-1.0-0.9-0.6-0.2-0.1-0.2-0.2-0.2-0.2-0.2-0.2-0.2-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.3-0.2

us-gaap:AccumulatedOtherComprehensiveIncomeLossNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value-14.9-15.7-14.8-16.8-17.7-18.0-18.7-20.1-20.5-20.9-21.8-16.2-17.0-17.2-14.2-16.1-17.2-17.4-17.6-18.4-18.6-18.8-19.1-14.0-24.4-27.1-27.3-17.6-17.4-17.3-17.5-34.0-34.1-36.8-39.5-32.8-26.8
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax12.120.89.48.78.07.820.215.425.439.658.6-648.081.390.532.736.848.388.870.110.311.918.154.471.455.058.254.042.342.040.740.156.355.059.160.354.946.3
Percentage of Assets-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.2-0.2-0.2-0.2-0.2-0.1
Percentage of Assets us-gaap:AccumulatedDefinedBenefitPlansAdjustment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value-113.1-63.3-147.9-181.8-207.8-210.5-77.2-113.4-62.8-32.3-13.020-1.7-0.3-29.4-28.1-18.8-2.0-6.9-162.3-139.7-86.2-15.5-5.9-20.0-20.7-23.6-23.9-24.5-25.2-25.8-26.6-27.2-27.7-28.6-31.8-34.8
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax91.583.894.493.993.691.383.487.077.761.234.9832.08.11.667.764.352.810.227.590.789.483.044.230.145.044.446.657.559.259.359.244.043.944.543.753.360.1
Percentage of Assets-0.5-0.3-0.7-0.8-0.9-0.9-0.3-0.5-0.3-0.1-0.10.1-0.0-0.0-0.1-0.1-0.1-0.0-0.0-0.9-0.8-0.5-0.1-0.0-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.1-0.2-0.2
Percentage of Assets us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Accumulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-31
Value4.43.56.05.03.6-2.13.33.22.50.4-2.4-2.1-2.2-1.50.20.50.4-0.2-0.61.72.01.2-0.50.30.01.20.3-0.10.50.0-0.30.2-0.72.22.64.93.7
Percentage of AccumulatedOtherComprehensiveIncomeLossNetOfTax-3.6-4.6-3.8-2.6-1.60.9-3.6-2.5-3.1-0.86.5-84.010.57.9-0.5-1.1-1.11.02.4-0.9-1.3-1.21.4-1.5-0.0-2.6-0.60.2-1.2-0.00.7-0.31.1-3.5-4.0-8.2-6.4
Percentage of Assets0.00.00.00.00.0-0.00.00.00.00.0-0.0-0.0-0.0-0.00.00.00.0-0.0-0.00.00.00.0-0.00.00.00.00.0-0.00.00.0-0.00.0-0.00.00.00.00.0
Percentage of Assets us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Treasury Stock Value

us-gaap:TreasuryStockValue

us-gaap:TreasuryStockValue


Treasury
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value9999999999999999999999999999959494938887878679797979585858584848484840404040303030302725
Percentage of TreasuryStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.50.50.40.40.40.40.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.50.30.30.20.20.30.30.20.20.20.20.20.20.20.20.10.20.20.20.10.1

Minority Interest

us-gaap:MinorityInterest

us-gaap:MinorityInterest


Minority
Period End2021-06-302021-03-312020-12-312015-06-302015-03-312014-12-31
Value9094859509460.0
Percentage of MinorityInterest100.0100.0100.0100.0100.00.0
Percentage of Assets0.40.40.43.73.80.0

Minority Interest Decrease From Distributions To Noncontrolling Interest Holders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders


Minority
Period End2021-06-302015-12-312015-09-302015-06-302015-03-31
Value0.30.0232-4.90.0
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.00.0100.0100.00.0
Percentage of Assets0.00.00.00.00.0

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302015-06-302015-03-31
Value0.3222-227.1
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0-4534.70.0
Percentage of Assets0.00.00.0
Percentage of Assets us-gaap:NoncontrollingInterest0.00.00.0

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
Value254448245150337369351305527399-387.1117421388212-121.824041127144184302262785116044332352573943581844454493331702914807658313422392-70.031983
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 RevenueFromContractWithCustomerExcludingAssessedTax26.729.821.317.536.224.225.934.354.421.8-27.013.842.922.615.5-13.824.325.720.95.220.521.123.99.643.728.125.621.019.217.022.417.136.725.223.717.828.128.95.15.425.618.922.4-6.227.33.5

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-460.6-401.8520-513.3-402.0-484.6-528.6-495.8-522.6-375.4-549.6-505.4-472.2-398.9-502.4-514.9-447.0-344.2-414.7-453.2-399.7-315.3-461.33400-604.9-388.9-604.4-614.6-489.7-407.9-640.1-533.2-472.0-246.1-473.9-382.4-274.2-294.7-347.4-378.5-248.3-175.1-182.2-367.2-199.5-194.4
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-48.4-26.745.2-59.6-43.1-31.8-38.9-55.6-53.9-20.5-38.3-59.1-48.1-23.2-36.7-58.3-45.1-21.5-32.0-52.6-44.5-21.9-42.0416.1-51.7-18.1-35.7-54.7-36.7-17.6-40.1-49.5-38.9-13.8-33.6-40.0-26.4-17.8-23.3-35.4-20.2-7.8-10.4-32.3-17.0-8.2

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
Value199-75.4-708.22764.8179288194-132.91610043608717299638196-64.915340820720182-3943.2548-198.817937821225293319-30.3-137.9164171-3.3-158.3260282-68.2-193.7-212.4440-222.9205
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 RevenueFromContractWithCustomerExcludingAssessedTax21.0-5.0-61.432.10.511.821.221.9-13.70.969.942.18.91.021.972.219.8-4.111.947.523.11.416.6-482.546.9-9.210.633.715.91.118.429.7-2.5-7.711.618.0-0.3-9.517.526.5-5.6-8.7-12.138.7-19.08.7

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
Value186185183180177184182182177175161148144144141143142143141136136132133132167157154153149148145144143143141126148146129134134138141153151149
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 Other Operating Capital Net

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet

us-gaap:IncreaseDecreaseInOtherOperatingCapitalNet


Increase
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value168972-71.2147-155.8-18.227
Percentage of IncreaseDecreaseInOtherOperatingCapitalNet100.0100.0100.0100.0100.0100.0100.0100.0

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
Value254448245150337369351305527399-387.1117421388212-121.824041127144184302262785116044332352573943581844454493331702914807658313422392-70.031983
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 RevenueFromContractWithCustomerExcludingAssessedTax26.729.821.317.536.224.225.934.354.421.8-27.013.842.922.615.5-13.824.325.720.95.220.521.123.99.643.728.125.621.019.217.022.417.136.725.223.717.828.128.95.15.425.618.922.4-6.227.33.5

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value6029584-172.9-4.775-139.36.6296218-11.7-339.524276-52.414-44.421188272817959-4.9-36.4268154317826615148712601341969193143438205313328197
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.319.67.3-20.1-0.55.0-10.30.730.611.9-0.8-39.72.516.1-3.81.6-4.513.26.83.23.212.55.4-0.6-3.112.59.12.85.911.59.54.55.914.69.52.06.711.71.03.23.29.21.82.92.48.4

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value5629687-172.9-4.775-139.36.6296218-11.7-339.524276-52.414-44.421188272817959-4.9-27.72751543178266
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.019.77.6-20.1-0.55.0-10.30.730.611.9-0.8-39.72.516.1-3.81.6-4.513.26.83.23.212.55.4-0.6-2.412.89.12.85.911.5

us-gaap:ProfitLoss us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312015-06-302015-03-31
Value-3.41.08.76.9
Percentage of ProfitLoss-6.00.3-31.42.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax-0.40.10.70.3
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:NoncontrollingInterest0.00.00.00.0

us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302015-06-302015-03-31
Value6029584-172.9-4.775-139.36.6296218-11.7-339.524-36.4268
Percentage of ProfitLoss106.099.796.1100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0131.497.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax6.319.67.3-20.1-0.55.0-10.30.730.611.9-0.8-39.72.5-3.112.5
Percentage of RevenueFromContractWithCustomerExcludingAssessedTax us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

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-460.6-401.8520-513.3-402.0-484.6-528.6-495.8-522.6-375.4-549.6-505.4-472.2-398.9-502.4-514.9-447.0-344.2-414.7-453.2-399.7-315.3-461.33400-604.9-388.9-604.4-614.6-489.7-407.9-640.1-533.2-472.0-246.1-473.9-382.4-274.2-294.7-347.4-378.5-248.3-175.1-182.2-367.2-199.5-194.4
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-48.4-26.745.2-59.6-43.1-31.8-38.9-55.6-53.9-20.5-38.3-59.1-48.1-23.2-36.7-58.3-45.1-21.5-32.0-52.6-44.5-21.9-42.0416.1-51.7-18.1-35.7-54.7-36.7-17.6-40.1-49.5-38.9-13.8-33.6-40.0-26.4-17.8-23.3-35.4-20.2-7.8-10.4-32.3-17.0-8.2

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value431367465472367452492466489353521464462370479484420312391410371301437-67.7583407586588466386582495432369474404326292351329235209250216198138
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value199-75.4-708.22764.8179288194-132.91610043608717299638196-64.915340820720182-3943.2548-198.817937821225293319-30.3-137.9164171-3.3-158.3260282-68.2-193.7-212.4440-222.9205
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 RevenueFromContractWithCustomerExcludingAssessedTax21.0-5.0-61.432.10.511.821.221.9-13.70.969.942.18.91.021.972.219.8-4.111.947.523.11.416.6-482.546.9-9.210.633.715.91.118.429.7-2.5-7.711.618.0-0.3-9.517.526.5-5.6-8.7-12.138.7-19.08.7

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302017-12-312017-09-302016-12-312016-09-302015-12-312015-09-302014-12-312014-09-302013-12-312013-09-302012-12-312012-09-302011-12-312011-09-30
Value0.019740.07500.00.05007500.05000.0-2745.90.07484920.00.00.04940.0
Percentage of ProceedsFromIssuanceOfLongTermDebt0.0100.00.0100.00.00.0100.0100.00.0100.00.0100.00.0100.0100.00.00.00.0100.00.0

Payments Of Dividends Common Stock

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsOfDividendsCommonStock


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
Value86868080808074747474707066655857565653534949494982828282787878787474746865656464646464636363
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value18.817.412.627.34.917-0.2450.0562.8330.1960.2120.3780.2180.1830.1850.3610.1520.3750.3650.0040.2640.3770.3840.0580.2820.3580.354-0.0080.4510.3350.3790.0010.360.3120.354-0.0050.3650.3480.347-0.0060.320.4320.3460.006-0.2010.355
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value14701485133012924302393548974491418138293671
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Unrecognized Tax Benefits

us-gaap:UnrecognizedTaxBenefits

us-gaap:UnrecognizedTaxBenefits


Unrecognized
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-312008-12-31
Value21231.21.42.60.92423281051291173.5
Percentage of UnrecognizedTaxBenefits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Deferred Tax Assets Valuation Allowance

us-gaap:DeferredTaxAssetsValuationAllowance

us-gaap:DeferredTaxAssetsValuationAllowance


Deferred
Period End2020-12-31
Value6400000.0
Percentage of DeferredTaxAssetsValuationAllowance100.0

nix:ATMProgramEquityRemainingAvailableforIssuance us-gaap:StatementEquityComponents

nix:ATMProgramEquityRemainingAvailableforIssuance

nix:AtTheMarketProgram


A
Period End2021-06-302021-03-31
Value-150.0600
Percentage of ATMProgramEquityRemainingAvailableforIssuance100.0100.0

nix:BusinessesImpactedbyIncident dei:LegalEntity

nix:BusinessesImpactedbyIncident

nix:ColumbiaOfMassachusetts


Businesses
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0700.0000700.0000700.0
Percentage of BusinessesImpactedbyIncident0.0100.00.00.00.0100.00.00.00.0100.0

nix:CashContribution dei:LegalEntity

nix:CashContribution

nix:NIPSCO


Cash
Period End2021-03-312020-12-31
Value0.10.7
Percentage of CashContribution100.0100.0

nix:TaxEquityPartner


Cash
Period End2021-03-312020-12-31
Value7.586
Percentage of CashContribution7500.012300.0

nix:CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions

nix:CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions


Cash
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value23182-66.5106-93.159-21.6100-9.2-265.0160176-21.1
Percentage of CashFromFinancingActivitiesRelatedToChangeInShortTermBorrowingsDueToSecuritizationTransactions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:CharitableContributions

nix:CharitableContributions


Charitable
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302017-12-312017-09-30
Value-0.6-0.3-1.1-1.120-11.1-16.4-0.8
Percentage of CharitableContributions100.0100.0100.0100.0100.0100.0100.0100.0

nix:CoalfiredGeneratingCapacityPercentofTotalCapacity

nix:CoalfiredGeneratingCapacityPercentofTotalCapacity


Coalfired
Period End2020-12-31
Value0
Percentage of CoalfiredGeneratingCapacityPercentofTotalCapacity0.0

nix:CoalfiredGeneratingCapacityPercentofTotalCoalFiredCapacity

nix:CoalfiredGeneratingCapacityPercentofTotalCoalFiredCapacity


Coalfired
Period End2020-12-31
Value0
Percentage of CoalfiredGeneratingCapacityPercentofTotalCoalFiredCapacity0.0

nix:CostsResultingfromtheGreaterLawrenceIncident

nix:CostsResultingfromtheGreaterLawrenceIncident


Costs
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-31
Value1.02.05.09.078211031023
Percentage of CostsResultingfromtheGreaterLawrenceIncident100.0100.0100.0100.0100.0100.0100.0100.0

nix:DebtInstrumentTendered

nix:DebtInstrumentTendered


Debt
Period End2020-08-31
Value969
Percentage of DebtInstrumentTendered100.0

nix:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicCostDiscountRateForInterestCost us-gaap:RetirementPlanType

nix:DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicCostDiscountRateForInterestCost

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-03-31
Value1.57
Percentage of DefinedBenefitPlanAssumptionsUsedInCalculatingNetPeriodicCostDiscountRateForInterestCost100.0

nix:DefinedBenefitPlanPensionAssetIncreaseDecreaseForRemeasurementDueToSettlement us-gaap:RetirementPlanType

nix:DefinedBenefitPlanPensionAssetIncreaseDecreaseForRemeasurementDueToSettlement

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-03-31
Value-5800000.0
Percentage of DefinedBenefitPlanPensionAssetIncreaseDecreaseForRemeasurementDueToSettlement100.0

nix:ExpensesOtherThanThirdPartyClaims

nix:ExpensesOtherThanThirdPartyClaims


Expenses
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-31
Value1.05.07.09.0322070266
Percentage of ExpensesOtherThanThirdPartyClaims100.0100.0100.0100.0100.0100.0100.0100.0

nix:ExpensesOtherThanThirdPartyClaims dei:LegalEntity, us-gaap:Range

nix:ColumbiaOfMassachusetts, srt:Maximum


Expenses
Period End2020-12-312020-03-312019-12-312019-09-30
Value-5.00.0200.0
Percentage of ExpensesOtherThanThirdPartyClaims-500.00.062.50.0

nix:ColumbiaOfMassachusetts, srt:Minimum


Expenses
Period End2020-12-312020-03-312019-12-312019-09-30
Value0.00.0200.0
Percentage of ExpensesOtherThanThirdPartyClaims0.00.062.50.0

nix:ExpensesRelatedtoThirdPartyClaims

nix:ExpensesRelatedtoThirdPartyClaims


Expenses
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-31
Value0.0-3.0-2.00.0461.033757
Percentage of ExpensesRelatedtoThirdPartyClaims0.0100.0100.00.0100.0100.0100.0100.0

nix:ExpensesRelatedtoThirdPartyClaims dei:LegalEntity, us-gaap:Range

nix:ColumbiaOfMassachusetts, srt:Maximum


Expenses
Period End2020-12-312020-03-31
Value0.0-10.0
Percentage of ExpensesRelatedtoThirdPartyClaims0.00.0

nix:ColumbiaOfMassachusetts, srt:Minimum


Expenses
Period End2021-03-312020-12-312020-03-312019-03-31
Value4.00.00.0204
Percentage of ExpensesRelatedtoThirdPartyClaims0.00.00.00.0

nix:ForwardContractIndexedToIssuersEquityForwardRatePerShareAtFairValue us-gaap:StatementEquityComponents

nix:ForwardContractIndexedToIssuersEquityForwardRatePerShareAtFairValue

nix:ForwardFebruary21Member


Forward
Period End2021-06-302021-03-31
Value-0.2622.25
Percentage of ForwardContractIndexedToIssuersEquityForwardRatePerShareAtFairValue100.0100.0

nix:FutureCashContribution dei:LegalEntity

nix:FutureCashContribution

nix:NIPSCO


Future
Period End2020-12-31
Value100000.0
Percentage of FutureCashContribution100.0

nix:TaxEquityPartner


Future
Period End2020-12-31
Value7500000.0
Percentage of FutureCashContribution7500.0

nix:GasMetersAffected dei:LegalEntity

nix:GasMetersAffected

nix:ColumbiaOfMassachusetts


Gas
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value07500.00007500.00007500.0
Percentage of GasMetersAffected0.0100.00.00.00.0100.00.00.00.0100.0

nix:GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense

nix:GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense


Greater
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302018-12-31
Value1.02.05.09.0-52.021-332.0888
Percentage of GreaterLawrenceIncidentImpactonOperationandMaintenanceExpense100.0100.0100.0100.0100.0100.0100.0100.0

nix:ImpairmentAndGainLossOnSaleOfAssetsNet

nix:ImpairmentAndGainLossOnSaleOfAssetsNet


Impairment
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
Value-0.18.14110.3-0.6-0.10.1-0.2-0.10.20.80.70.0-0.35.60.0
Percentage of ImpairmentAndGainLossOnSaleOfAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.00.0

nix:IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets

nix:IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-31
Value8200000.0-10700000.09600000.0-7200000.0-5300000.0-12100000.0300000.0-8000000.0-10100000.0-58300000.03000000.0-400000.0-700000.01900000.01700000.0
Percentage of IncreaseDecreaseInDeferredChargesAndOtherNonCurrentAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:IncreaseDecreaseinCustomerAccountsReceivableBilledLessReserve

nix:IncreaseDecreaseinCustomerAccountsReceivableBilledLessReserve


Increase
Period End2021-03-312020-12-31
Value107109
Percentage of IncreaseDecreaseinCustomerAccountsReceivableBilledLessReserve100.0100.0

nix:IncreaseDecreaseinCustomerAccountsReceivableUnbilledLessReserve

nix:IncreaseDecreaseinCustomerAccountsReceivableUnbilledLessReserve


Increase
Period End2021-03-312020-12-31
Value-82900000.0148400000.0
Percentage of IncreaseDecreaseinCustomerAccountsReceivableUnbilledLessReserve100.0100.0

nix:IncreaseDecreaseinEffectiveTaxRate

nix:IncreaseDecreaseinEffectiveTaxRate


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-12-312019-09-302019-06-302018-12-312018-09-30
Value-472.941.97.0-256.04.721-0.3222.6150.0130.0170.066
Percentage of IncreaseDecreaseinEffectiveTaxRate100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:IncrementalCommonSharesAttributableToDilutiveEffectOfEquityUnitPurchaseAgreementsIfConverted

nix:IncrementalCommonSharesAttributableToDilutiveEffectOfEquityUnitPurchaseAgreementsIfConverted


Incremental
Period End2021-06-30
Value28
Percentage of IncrementalCommonSharesAttributableToDilutiveEffectOfEquityUnitPurchaseAgreementsIfConverted100.0

nix:MiscellaneousNonOperatingIncomeExpense

nix:MiscellaneousNonOperatingIncomeExpense


Miscellaneous
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
Value-300000.0-400000.03800000.0600000.0600000.0-700000.0200000.0200000.0-900000.0-1700000.0200000.0600000.01700000.0-1500000.0200000.0100000.0
Percentage of MiscellaneousNonOperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:PaymentToRenewableGenerationAssetDeveloper

nix:PaymentToRenewableGenerationAssetDeveloper


Payment
Period End2021-03-31
Value7.4
Percentage of PaymentToRenewableGenerationAssetDeveloper100.0

nix:PenaltyPerViolationofEmergencyResponsePlan dei:LegalEntity, us-gaap:Range

nix:PenaltyPerViolationofEmergencyResponsePlan

nix:ColumbiaOfMassachusetts, srt:Maximum


Penalty
Period End2020-09-302020-06-302020-03-31
Value00250000.0
Percentage of PenaltyPerViolationofEmergencyResponsePlan0.00.0100.0

nix:PenaltyforViolationsofEmergencyResponsePlan dei:LegalEntity, us-gaap:Range

nix:PenaltyforViolationsofEmergencyResponsePlan

nix:ColumbiaOfMassachusetts, srt:Maximum


Penaltyfor
Period End2020-09-302020-06-302020-03-31
Value0.00.020
Percentage of PenaltyforViolationsofEmergencyResponsePlan0.00.0100.0

nix:PensionandOtherPostretirementNonServiceCost

nix:PensionandOtherPostretirementNonServiceCost


Pensionand
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
Value8.68.52.90.63.12.7-7.8-2.8-3.1-2.83.32.46.16.2-0.5-11.8
Percentage of PensionandOtherPostretirementNonServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:PipelineReplacementExpenses dei:LegalEntity

nix:PipelineReplacementExpenses

nix:ColumbiaOfMassachusetts


Pipeline
Period End2021-03-312020-12-312019-03-31
Value0.00.010.0
Percentage of PipelineReplacementExpenses0.00.0100.0

nix:PleaAgreementCriminalFine dei:LegalEntity

nix:PleaAgreementCriminalFine

nix:ColumbiaOfMassachusetts


Plea
Period End2021-06-302021-03-312020-12-31
Value0.0530.0
Percentage of PleaAgreementCriminalFine0.0100.00.0

nix:ProceedsFromInsuranceSettlement

nix:ProceedsFromInsuranceSettlement


Proceeds
Period End2020-12-312020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.00.0130260297108
Percentage of ProceedsFromInsuranceSettlement0.00.0100.0100.0100.0100.0

nix:SaleOfEmissionReductionCredits

nix:SaleOfEmissionReductionCredits


Sale
Period End2020-12-312020-09-30
Value04600000.0
Percentage of SaleOfEmissionReductionCredits0.0100.0

nix:SecuritizationTransactionFees

nix:SecuritizationTransactionFees


Securitization
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value400000.0500000.0600000.0800000.0700000.02600000.0600000.0600000.0800000.02600000.0400000.0700000.0800000.0600000.0600000.0
Percentage of SecuritizationTransactionFees100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:SecuritizationTransactionFees us-gaap:FinancialInstrument

nix:AccountsReceivableProgram


Securitization
Period End2021-06-302020-06-30
Value400000.0800000.0
Percentage of SecuritizationTransactionFees0.0100.0

nix:ServiceAreaByCounty

nix:ServiceAreaByCounty


Service
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value020.000020.000020.0
Percentage of ServiceAreaByCounty0.0100.00.00.00.0100.00.00.00.0100.0

nix:StockIssuedDuringThePeriodEquityUnitsValue

nix:StockIssuedDuringThePeriodEquityUnitsValue


Stock
Period End2021-06-30
Value665
Percentage of StockIssuedDuringThePeriodEquityUnitsValue100.0

nix:StockIssuedDuringThePeriodEquityUnitsValue us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-30
Value-173.3
Percentage of StockIssuedDuringThePeriodEquityUnitsValue-26.0

us-gaap:PreferredStock


Stock
Period End2021-06-30
Value838
Percentage of StockIssuedDuringThePeriodEquityUnitsValue126.0

nix:StockIssuedDuringThePeriodSharesEquityUnits us-gaap:StatementEquityComponents

nix:StockIssuedDuringThePeriodSharesEquityUnits

us-gaap:PreferredStock


Stock
Period End2021-06-30
Value863000.0
Percentage of StockIssuedDuringThePeriodSharesEquityUnits100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CapitalExpendituresIncurredButNotYetPaid


Capital
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value3715510-8.117150361745123-15.5-24.446145-5.9-8.630108-9.1-175.4116189-8.11963131-52.85632114431434715.8276.4583110
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value-6.3-28.958-86.0-59.4641114.6-128.43967
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareDeclared

us-gaap:CommonStockDividendsPerShareDeclared


Common
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
Value0.220.440.210.4200.20.20.400.1950.1950.3900.1750.1750.3500.1650.1650.3100.3100.5200.260.260.500.250.250.4800.240.240.4600.230.230.4600.230.230.46
Percentage of CommonStockDividendsPerShareDeclared100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.00.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:DeferredIncomeTaxesAndTaxCredits

us-gaap:DeferredIncomeTaxesAndTaxCredits


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
Value155541-59.48.5-19.9-2.2-6.17451-161.8-92.79.5562107.9-21.010944132210275-59.1-15.91357834371488831501161641136921333329969921127
Percentage of DeferredIncomeTaxesAndTaxCredits100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-1.2-1.2-1.1-1.2-1.3-1.3-2.0-0.5-0.5-0.5-3.8-0.9-0.9-0.9-0.8-0.7-0.7-0.8-0.7-0.8-0.8
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-5.5-5.3-7.8-8.6-8.7-8.7-45.2-11.3-11.4-11.4-40.6-10.2-10.2-10.2-12.9-13.2-13.4-13.4-15.3-15.3-15.3
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses458.3441.7709.1716.7669.2669.22260.02260.02280.02280.01068.41133.31133.31133.31612.51885.71914.31675.02185.71912.51912.5

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-600000.0-600000.0-700000.0-400000.0-500000.0-500000.0-3200000.0-800000.0-800000.0-800000.0-4000000.0-1000000.0-1000000.0-1000000.0-1100000.0-1100000.0-1100000.0-1100000.0-1300000.0-1200000.0-1200000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value100000.0200000.0200000.0200000.0200000.0000-400000.0-100000.0-100000.0-100000.0-200000.0-100000.0-200000.0-200000.000-100000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit-14.3-50.0-40.0-40.0-6.2-0.0-0.0-0.010.010.010.010.018.29.118.218.2-0.0-0.08.3

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-03-312020-12-312018-08-31
Value2.8100
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostDiscountRate100.00.00.0

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-03-312020-12-312018-08-31
Value4.80.50
Percentage of DefinedBenefitPlanAssumptionsUsedCalculatingNetPeriodicBenefitCostExpectedLongTermReturnOnAssets100.0100.00.0

us-gaap:DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312018-09-30
Value1600000.01400000.0
Percentage of DefinedBenefitPlanBenefitObligationIncreaseDecreaseForRemeasurementDueToSettlement100.0100.0

us-gaap:DefinedBenefitPlanContributionsByEmployer us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanContributionsByEmployer

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value5.15.14.95.25.26.35.26.16.05.74.25.55.85.59.87.3
Percentage of DefinedBenefitPlanContributionsByEmployer100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-30
Value1.30.70.80.60.70.80.80.80.70.60.80.70.70.70.7277
Percentage of DefinedBenefitPlanContributionsByEmployer25.513.716.311.513.512.715.413.111.710.519.012.712.112.77.13794.5

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value3.83.83.63.63.63.6133.33.33.3143.73.73.74.04.03.94.04.34.34.3
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value25252628282810827272714235363631303030333333
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets665.8678.9736.1786.1788.9788.9830.5824.2824.2824.2955.0956.8978.4981.1795.0770.0774.4757.5774.4772.1772.1

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value2.52.53.83.83.93.9194.84.84.8174.44.44.44.44.54.44.55.55.55.5
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value7.97.711131313721818186716161616171717222222
Percentage of DefinedBenefitPlanInterestCost316.0308.0302.6344.7346.2346.2376.6377.1379.2379.2381.2381.8377.3377.3381.8380.0390.9382.2409.1407.3407.3

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value0.80.83.82.72.72.72.52.52.52.51.81.91.91.91.31.31.31.41.92.12.0
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value-1.1-1.93.39.72.02.016119.79.77.07.61.9-1.78.4177.77.6121212
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost-137.5-237.586.8359.374.174.1672.0456.0388.0388.0388.9400.0100.0-89.5646.21338.5592.3542.9636.8581.0605.0

us-gaap:DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1 us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-09-302019-09-30
Value-3300000.0-3300000.0-8000000.0-1900000.0
Percentage of DefinedBenefitPlanRecognizedNetGainLossDueToSettlementsAndCurtailments1100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanServiceCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value1.51.51.71.71.61.65.11.31.31.35.01.31.31.31.21.21.21.21.31.31.2
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-30
Value7.57.67.98.18.08.0297.37.37.3317.87.97.97.67.47.57.57.67.77.7
Percentage of DefinedBenefitPlanServiceCost500.0506.7464.7476.5500.0500.0572.5561.5561.5561.5626.0600.0607.7607.7633.3616.7625.0625.0584.6592.3641.7

us-gaap:DilutiveSecuritiesEffectOnBasicEarningsPerShareOther

us-gaap:DilutiveSecuritiesEffectOnBasicEarningsPerShareOther


Dilutive
Period End2021-06-30
Value400000.0
Percentage of DilutiveSecuritiesEffectOnBasicEarningsPerShareOther100.0

us-gaap:DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss

nix:MassachusettsBusinessDomain


Disposal
Period End2020-12-312020-09-302020-06-302019-12-312019-09-302019-06-30
Value-19.4-74.1-92.6-146.7-55.2319
Percentage of DisposalGroupIncludingDiscontinuedOperationOperatingIncomeLoss100.0100.0100.0100.0100.0100.0

us-gaap:DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown

us-gaap:DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown


Disposal
Period End2020-12-312020-09-30
Value1235
Percentage of DisposalGroupNotDiscontinuedOperationLossGainOnWriteDown100.0100.0

us-gaap:DividendsCommonStockCash

us-gaap:DividendsCommonStockCash


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value861720.08080160-0.174741490.170701310.159571130.15353990.0980.0164642-82.1-82.0-157.3
Percentage of DividendsCommonStockCash100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value861720.08080160-0.174741490.170701310.159571130.15353990.0980.0164642-82.1-82.0-157.3
Percentage of DividendsCommonStockCash100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:DividendsPreferredStockCash

us-gaap:DividendsPreferredStockCash


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value8.2270.0198.2270.0198.2280.011
Percentage of DividendsPreferredStockCash100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0

us-gaap:DividendsPreferredStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value8.2270.0198.2270.0198.2280.011
Percentage of DividendsPreferredStockCash100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate


Effective
Period End2021-06-302021-03-312020-12-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value021.000000.210000.35
Percentage of EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate0.0100.00.00.00.00.0100.00.00.00.0100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesRecovery

us-gaap:FinancingReceivableAllowanceForCreditLossesRecovery


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.84.24.32.23.34.6
Percentage of FinancingReceivableAllowanceForCreditLossesRecovery100.0100.0100.0100.0100.0100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesRecovery us-gaap:StatementBusinessSegments

nix:ElectricOperations


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value0.10.10.10.00.20.0
Percentage of FinancingReceivableAllowanceForCreditLossesRecovery3.62.42.30.06.10.0

nix:GasDistributionOperations


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.70000000000000064.14.22.23.14.6
Percentage of FinancingReceivableAllowanceForCreditLossesRecovery96.497.697.7100.093.9100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesWriteOffs

us-gaap:FinancingReceivableAllowanceForCreditLossesWriteOffs


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value11118.64.88.47.9
Percentage of FinancingReceivableAllowanceForCreditLossesWriteOffs100.0100.0100.0100.0100.0100.0

us-gaap:FinancingReceivableAllowanceForCreditLossesWriteOffs us-gaap:StatementBusinessSegments

nix:ElectricOperations


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value2.52.40.00.51.5-1.0
Percentage of FinancingReceivableAllowanceForCreditLossesWriteOffs21.221.10.010.417.9-12.7

nix:GasDistributionOperations


Financing
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value9.39.08.64.36.9-6.9
Percentage of FinancingReceivableAllowanceForCreditLossesWriteOffs78.878.9100.089.682.1-87.3

us-gaap:ForwardContractIndexedToIssuersEquityForwardRate us-gaap:StatementEquityComponents

us-gaap:ForwardContractIndexedToIssuersEquityForwardRate

nix:ForwardAgreement


Forward
Period End2020-12-152019-12-112019-11-212019-09-302019-06-302019-03-312018-11-062018-12-312017-12-08
Value22.7728.8326.01-0.11-0.126.426.4326.5527.24
Percentage of ForwardContractIndexedToIssuersEquityForwardRate100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:ForwardAgreementSeptember20


Forward
Period End2020-09-30
Value22.28
Percentage of ForwardContractIndexedToIssuersEquityForwardRate0.0

nix:ForwardAugust20


Forward
Period End2020-09-03
Value23.25
Percentage of ForwardContractIndexedToIssuersEquityForwardRate0.0

nix:ForwardAugust20Member


Forward
Period End2020-09-30
Value23.25
Percentage of ForwardContractIndexedToIssuersEquityForwardRate0.0

nix:ForwardJune21Member


Forward
Period End2021-06-30
Value25.63
Percentage of ForwardContractIndexedToIssuersEquityForwardRate0.0

nix:ForwardSeptember20


Forward
Period End2020-12-152020-09-16
Value21.8222.28
Percentage of ForwardContractIndexedToIssuersEquityForwardRate95.80.0

us-gaap:ForwardContractIndexedToIssuersEquityShares us-gaap:StatementEquityComponents

us-gaap:ForwardContractIndexedToIssuersEquityShares

nix:ForwardAgreementSeptember20


Forward
Period End2020-09-30
Value1.452102
Percentage of ForwardContractIndexedToIssuersEquityShares100.0

nix:ForwardAugust20


Forward
Period End2020-09-03
Value2.809029
Percentage of ForwardContractIndexedToIssuersEquityShares0.0

nix:ForwardAugust20Member


Forward
Period End2020-09-30
Value2.809029
Percentage of ForwardContractIndexedToIssuersEquityShares193.4

nix:ForwardJune21Member


Forward
Period End2021-06-30
Value5.852475
Percentage of ForwardContractIndexedToIssuersEquityShares0.0

nix:ForwardSeptember20


Forward
Period End2020-09-16
Value1.452102
Percentage of ForwardContractIndexedToIssuersEquityShares0.0

us-gaap:GainLossOnSaleOfBusiness

us-gaap:GainLossOnSaleOfBusiness


Gain
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-06-302019-03-31
Value100000.0-8100000.0-35600000.0-84400000.0-280200000.000
Percentage of GainLossOnSaleOfBusiness100.0100.0100.0100.0100.00.00.0

us-gaap:GainLossOnSalesOfAssetsAndAssetImpairmentCharges us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

us-gaap:GainLossOnSalesOfAssetsAndAssetImpairmentCharges

nix:MassachusettsBusinessDomain


Gain
Period End2020-09-302020-06-302020-03-31
Value-392.6-357.7-274.5
Percentage of GainLossOnSalesOfAssetsAndAssetImpairmentCharges100.0100.0100.0

us-gaap:IncreaseDecreaseInAssetRetirementObligations

us-gaap:IncreaseDecreaseInAssetRetirementObligations


Increase
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value210.00.569410.08.04.83.410.0
Percentage of IncreaseDecreaseInAssetRetirementObligations100.00.0100.0100.0100.00.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities

us-gaap:IncreaseDecreaseInOtherOperatingLiabilities


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-13.8-8.4265.02.3-11.927-1.03.532-32.855-11.4-14.4-16.821-24.4-14.55.1-4.5-2.62.5-6.7-25.67.74.3-9.4-1.53.84.0-3.23.1-7.5-1.9-18.25.2-5.14.04937-5.70.9-3.5-12.6-2.35.2
Percentage of IncreaseDecreaseInOtherOperatingLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInRegulatoryAssetsAndLiabilities

us-gaap:IncreaseDecreaseInRegulatoryAssetsAndLiabilities


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-13.1-8.4-60.97.1-4.1-12.9152941-0.411480-24.6-117.1-70.43646-69.3-14.366548112814-34.8-90.6263-2.3-11.9-2.9-407.6-30.6-35.1-5.8148-89.0-8.51.2362-10.9-9.7-18.6-60.0-5.6-50.5-47.8
Percentage of IncreaseDecreaseInRegulatoryAssetsAndLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToContingentlyIssuableShares

us-gaap:IncrementalCommonSharesAttributableToContingentlyIssuableShares


Incremental
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value800000.0630000.0-126000.0845000.010000.0-11000.0800000.01062000.0861000.0715000.044000.0604000.092000.0360000.019000.0228000.0124000.036000.000178000.0335000.0417000.0725000.0616000.0399000.0381000.0369000.0350000.0276000.0164000.0434000.0284000.0158000.0-70000.01119000.01078000.01112000.07000.0957000.0300000.0
Percentage of IncrementalCommonSharesAttributableToContingentlyIssuableShares100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToEquityForwardAgreements

us-gaap:IncrementalCommonSharesAttributableToEquityForwardAgreements


Incremental
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-30
Value0.60.3370.00.0-0.0860.0870.3980.1050.00.00.00.00.00.0-2.388.399109.2750.876.7315.4224.2030.5460.415
Percentage of IncrementalCommonSharesAttributableToEquityForwardAgreements100.0100.00.00.0100.0100.0100.0100.00.00.00.00.00.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements

us-gaap:IncrementalCommonSharesAttributableToShareBasedPaymentArrangements


Incremental
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-30
Value300000.0288000.0-15000.0207000.013000.06000.0136000.0133000.071000.0264000.0-45000.0653000.0-290000.01265000.0-52000.01372000.01045000.01703000.0-1238000.03375000.015000.0468000.06000.0451000.0431000.0442000.0-21000.0490000.0471000.0523000.0-82000.0654000.0620000.0615000.0-3000.0376000.0342000.0317000.0329000.0410000.0511000.0
Percentage of IncrementalCommonSharesAttributableToShareBasedPaymentArrangements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:InsuranceRecoveries

us-gaap:InsuranceRecoveries


Insurance
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value0.00.00.00.01300.0435100135
Percentage of InsuranceRecoveries0.00.00.00.0100.00.0100.0100.0100.0

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance


Noncontrolling
Period End2021-06-302021-03-312015-06-302015-03-31
Value-0.37.50.01168
Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance100.0100.00.0100.0

us-gaap:NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance us-gaap:StatementEquityComponents

us-gaap:NoncontrollingInterest


Noncontrolling
Period End2021-06-302021-03-312015-06-302015-03-31
Value-0.37.50.01168
Percentage of NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance100.0100.00.0100.0

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value900000.0-2500000.01000000.01400000.05700000.0-5400000.0100000.0700000.02100000.02800000.0-300000.0100000.0-700000.0-1700000.0-300000.0100000.0600000.0400000.0-2300000.0-300000.0800000.01700000.0-800000.0300000.0-1200000.0900000.0400000.0-600000.0500000.0300000.0-500000.0900000.0-2900000.0-400000.0-500000.0700000.0300000.0-2800000.0
Percentage of OtherComprehensiveIncomeLossAvailableForSaleSecuritiesAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax


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-48.98136288.7-138.138-49.6-28.2-16.1-20.922-2.0480.3-9.6-17.34.9153-23.2-53.1-69.4-17.8-1.01.31.0-9.8-0.60.20.6140.3-1.01.3
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


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
Value0.1-1.41.51.00.00.41.60.20.00.5-5.41.00.6-0.61.70.00.10.10.50.0-0.10.1-6.2-1.32.50.0-9.8-0.1-0.30.015-0.61.91.3
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-0.2-1.74.13.50.0-0.34.2-0.4-0.0-3.125.84.4-30.0-1.2566.7-0.0-0.62.00.3-0.00.2-0.134.8130.0192.30.0100.016.7-150.00.0102.0-200.0-190.0100.0

us-gaap:AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedges


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-49.88433262.7-133.336-50.7-30.5-19.3-15.021-2.051-0.9-9.7-18.24.6155-22.9-53.9-71.2-10.8-0.20.00.0-0.40.00.00.10.2-0.1-0.10.1
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax101.8104.492.392.231.096.595.3102.2108.2119.971.895.6100.0105.1-300.0101.0105.293.9101.298.7101.5102.660.720.00.00.04.1-0.00.016.71.3-33.310.07.7

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


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
Value0.8-2.21.31.26.0-5.20.20.92.32.7-0.50.0-0.6-1.9-0.50.10.80.2-2.3-0.30.91.7-0.80.5-1.21.00.4-0.50.50.5-0.51.0-2.8-0.1
Percentage of OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax-1.6-2.73.64.369.03.80.5-1.8-8.2-16.82.40.030.0-3.9-166.7-1.0-4.64.1-1.51.3-1.7-2.44.5-50.0-92.3100.0-4.183.3250.083.3-3.4333.3280.0-7.7

us-gaap:OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax

us-gaap:OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value-49.88433262.7-133.336-50.6-30.5-19.3-33.822-1.435-1.3-9.3-16.84.9155-22.6-53.5-70.7-9.60.20.70.90.30.60.70.60.80.60.50.90.50.80.91.0
Percentage of OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-48.181288.7-138.0-49.5-28.0-15.6-39.723-1.9330.3-8.1-16.05.5153-22.7-52.5-68.7-15.50.32.22.0-9.0-0.21.11.1
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent us-gaap:StatementEquityComponents

us-gaap:AccumulatedOtherComprehensiveIncome


Other
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value-48.181288.7-138.0-49.5-28.0-15.6-39.723-1.9330.3-8.1-16.05.5153-22.7-52.5-68.7-15.50.32.22.0-9.0-0.21.11.1
Percentage of OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value-800000.0900000.0-2000000.0-900000.0-300000.0-700000.0-1400000.0-400000.0-400000.0-900000.05600000.0-800000.0-200000.0-200000.0-1900000.0-1100000.0-200000.0-200000.0-800000.0-200000.0-200000.0-300000.05100000.0200000.0-2700000.0-200000.09700000.0200000.0100000.0-200000.0-16500000.0-100000.0-2700000.0-2700000.08700000.0-700000.0-700000.0-600000.0
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansAdjustmentNetOfTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax

us-gaap:OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value-0.2-0.90.2-0.2-0.20.3-1.0-0.1-0.1-0.41.70.0-0.1-0.1-1.3-0.5-0.2-0.10.3-0.1-0.2-0.10.11.80.0-0.70.0100.01.81.7-5.20.20.3
Percentage of OtherComprehensiveIncomeLossPensionAndOtherPostretirementBenefitPlansTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.00.0100.00.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-16.528118.60.9-44.112-16.7-10.06.5-11.27.5-0.511-0.8-5.8-10.33.096-14.0-33.0-43.60.40.30.40.40.40.50.40.30.6-16.60.60.6190.3-0.3190.71.8
Percentage of OtherComprehensiveIncomeUnrealizedGainLossOnDerivativesArisingDuringPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax

us-gaap:OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value300000.0-700000.0200000.0400000.01500000.0-1400000.0100000.0100000.0600000.0-700000.000-200000.0-400000.0-200000.00400000.0200000.0-1300000.0-100000.0400000.0900000.0500000.0200000.0-300000.0200000.0200000.0-2800000.0-500000.0-1700000.0-100000.0-100000.0-300000.0-1100000.0-700000.0500000.0-3100000.0200000.0300000.0
Percentage of OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherOperatingActivitiesCashFlowStatement

us-gaap:OtherOperatingActivitiesCashFlowStatement


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-31
Value5.43.5-13.15.6-0.27.9-19.75.27.16.5-13.94.326-15.6-22.06.11111-1.5-0.6-1.3-0.41.83.67.10.6
Percentage of OtherOperatingActivitiesCashFlowStatement100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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-3.00.80.4-0.90.7-0.1-0.90.62.4-3.61.51.2-16.79.9-2.4-3.63.60.8-6.9-38.43725221625-2.412118.1-7.01924185.310189.5109.723269.27.2269.310
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:PaymentsForRemovalCosts

us-gaap:PaymentsForRemovalCosts


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value32263635323428283025312627193023243130312621
Percentage of PaymentsForRemovalCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForRestructuring

us-gaap:PaymentsForRestructuring


Payments
Period End2021-03-31
Value8.4
Percentage of PaymentsForRestructuring100.0

us-gaap:PaymentsOfDividendsPreferredStockAndPreferenceStock

us-gaap:PaymentsOfDividendsPreferredStockAndPreferenceStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value198.1198.1198.1198.2199.1110.00.00.0
Percentage of PaymentsOfDividendsPreferredStockAndPreferenceStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

us-gaap:PaymentsOfStockIssuanceCosts

us-gaap:PaymentsOfStockIssuanceCosts


Payments
Period End2021-04-19
Value27
Percentage of PaymentsOfStockIssuanceCosts100.0

us-gaap:PaymentsOfStockIssuanceCosts nix:EquityUnitsComponents

nix:PurchaseContractLiability


Payments
Period End2021-04-19
Value4.5
Percentage of PaymentsOfStockIssuanceCosts16.7

us-gaap:PreferredStock


Payments
Period End2021-04-19
Value22
Percentage of PaymentsOfStockIssuanceCosts83.3

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt

us-gaap:PaymentsToAcquireAvailableForSaleSecuritiesDebt


Payments
Period End2021-03-312020-12-312020-03-312019-12-312019-03-312018-12-312018-09-302017-12-312017-09-30
Value164943362518242933
Percentage of PaymentsToAcquireAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PreferredStockAmountOfPreferredDividendsInArrears us-gaap:StatementClassOfStock

us-gaap:PreferredStockAmountOfPreferredDividendsInArrears

us-gaap:SeriesAPreferredStock


Preferred
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value1000000.06700000.06700000.01000000.06700000.0
Percentage of PreferredStockAmountOfPreferredDividendsInArrears100.0100.0100.0100.0100.0

us-gaap:PreferredStockDividendsPerShareDeclared us-gaap:StatementClassOfStock

us-gaap:PreferredStockDividendsPerShareDeclared

us-gaap:SeriesAPreferredStock


Preferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value028.25028.25028.25028.25028.25028.88
Percentage of PreferredStockDividendsPerShareDeclared0.0100.00.0100.00.0100.00.0100.00.0100.00.0100.0

us-gaap:SeriesBPreferredStock


Preferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value406.25812.50406.25406.25812.50406.25406.25862.1500
Percentage of PreferredStockDividendsPerShareDeclared0.02876.10.01438.10.02876.10.01438.10.03051.90.00.0

us-gaap:PreferredStockPerShareAmountsOfPreferredDividendsInArrears us-gaap:StatementClassOfStock

us-gaap:PreferredStockPerShareAmountsOfPreferredDividendsInArrears

us-gaap:SeriesAPreferredStock


Preferred
Period End2021-06-302021-03-312020-09-302020-06-302020-03-31
Value2.5116.6316.632.5116.63
Percentage of PreferredStockPerShareAmountsOfPreferredDividendsInArrears100.0100.0100.0100.0100.0

us-gaap:ProceedsFromDebtNetOfIssuanceCosts us-gaap:DebtInstrument, us-gaap:LongtermDebtType

us-gaap:ProceedsFromDebtNetOfIssuanceCosts

nix:A095NotesDue2025And170NotesDue2031, us-gaap:SeniorNotes


Proceeds
Period End2020-08-18
Value1980
Percentage of ProceedsFromDebtNetOfIssuanceCosts100.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


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
Value3.22.82003.73.83.72333.84.03.12363.96043.74.1286396.46.36.85.74.34.65.56.55.97.96.37.28.97.6126.9177.134612179.37.24.23.73.83.83.23.6
Percentage of ProceedsFromIssuanceOfCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromMinorityShareholders

us-gaap:ProceedsFromMinorityShareholders


Proceeds
Period End2021-03-31
Value7.5
Percentage of ProceedsFromMinorityShareholders100.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302011-12-312011-09-30
Value2.0-2.50.0-228.9-12.5-5.1-5.9-7.7-0.2-4.00.1-30.9-15.20.0-4.5-9.1-130.70.0-3.40.00.0-0.30.022-116.00.0-8.70.0-113.81130.0-3.2-354.33540.00.0-53.90.0
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.00.00.0100.00.0100.0100.00.0100.00.0100.0100.00.0100.0100.0100.00.00.0100.00.0

us-gaap:ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess

us-gaap:ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-520.017-35.1224-382.9-226.8308-365.9-499.0452
Percentage of ProceedsFromRepaymentsOfShortTermDebtMaturingInThreeMonthsOrLess100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt

us-gaap:ProceedsFromSaleOfAvailableForSaleSecuritiesDebt


Proceeds
Period End2021-03-312020-12-312020-03-312019-12-312019-03-312018-12-312018-09-302017-12-312017-09-30
Value164245282923113322
Percentage of ProceedsFromSaleOfAvailableForSaleSecuritiesDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths

us-gaap:ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths


Proceeds
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value0.00.08505000.01005000.0
Percentage of ProceedsFromShortTermDebtMaturingInMoreThanThreeMonths0.00.0100.0100.00.0100.0100.00.0

us-gaap:ProvisionForLoanLeaseAndOtherLosses

us-gaap:ProvisionForLoanLeaseAndOtherLosses


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value-3.38.817101610
Percentage of ProvisionForLoanLeaseAndOtherLosses100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForLoanLeaseAndOtherLosses us-gaap:StatementBusinessSegments

nix:ElectricOperations


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value-2.52.92.62.32.91.5
Percentage of ProvisionForLoanLeaseAndOtherLosses75.833.015.021.917.914.2

nix:GasDistributionOperations


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value-0.85.9148.2139.1
Percentage of ProvisionForLoanLeaseAndOtherLosses24.267.085.078.182.185.8

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest

us-gaap:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest


Public
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
Value3.41.55.01.81.41.70.92.92.51.71.65.03.93.72.14.33.72.5
Percentage of PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount

nix:ColumbiaOfPennsylvania, nix:DSICQ32020


Public
Period End2020-09-18
Value2.6
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount100.0

nix:NIPSCOGas, nix:TDSIC1


Public
Period End2020-08-25
Value1.3
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount0.0

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

nix:ColumbiaOfMaryland, nix:A2021STRIDE, us-gaap:SubsequentEvent


Public
Period End2020-10-29
Value1.3
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount0.0

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

us-gaap:PublicUtilitiesRequestedRateIncreaseDecreaseAmount

nix:ColumbiaOfVirginia, nix:A2021SAVE


Public
Period End2020-07-24
Value5.2
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount100.0

nix:NIPSCOElectric, nix:TDSIC7


Public
Period End2020-09-29
Value13
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount0.0

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

nix:ColumbiaOfKentucky, nix:A2021SMRP, us-gaap:SubsequentEvent


Public
Period End2020-10-15
Value5.8
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount0.0

nix:ColumbiaOfVirginia, nix:A2021SAVE, us-gaap:SubsequentEvent


Public
Period End2020-07-24
Value5.2
Percentage of PublicUtilitiesRequestedRateIncreaseDecreaseAmount100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value800000.0200000.0300000.0100000.00100000.0-300000.0100000.0200000.0500000.0-18800000.0800000.0100000.0-14700000.001500000.01300000.0600000.0600000.0500000.0600000.0700000.02300000.01300000.0900000.01000000.0800000.0400000.0900000.0500000.01900000.01300000.01300000.01900000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax us-gaap:StatementEquityComponents

us-gaap:AccumulatedDefinedBenefitPlansAdjustment


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value700000.0500000.0500000.0-100000.0300000.0300000.0-200000.0200000.0400000.0400000.0-200000.0-200000.0-400000.0800000.0200000.01100000.0100000.0100000.0300000.0200000.0300000.0200000.01100000.01100000.0200000.0200000.0100000.0-100000.0200000.0200000.01300000.0700000.0800000.01400000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax87.5250.0166.7-100.00.0300.066.7200.0200.080.01.1-25.0-400.0-5.40.073.37.716.750.040.050.028.647.884.622.220.012.5-25.022.240.068.453.861.573.7

us-gaap:AccumulatedNetUnrealizedInvestmentGainLoss


Reclassification
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value100000.0-300000.0-300000.0200000.0-300000.0-200000.0-100000.0-200000.0-200000.0100000.0200000.0100000.0-100000.0200000.0200000.00-200000.0200000.000-100000.000-200000.00-100000.00-100000.00-200000.00-100000.0-100000.0-300000.0
Percentage of ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax12.5-150.0-100.0200.00.0-200.033.3-200.0-100.020.0-1.112.5-100.0-1.40.00.0-15.433.30.00.0-16.70.00.0-15.40.0-10.00.0-25.00.0-40.00.0-7.7-7.7-15.8

us-gaap:RegulatedOperatingRevenueOther

us-gaap:RegulatedOperatingRevenueOther


Regulated
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
Value33395741307938404135253924332433
Percentage of RegulatedOperatingRevenueOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedOperatingRevenueOther us-gaap:StatementBusinessSegments

nix:ElectricOperations


Regulated
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
Value2123242523222728222221271821
Percentage of RegulatedOperatingRevenueOther63.159.642.161.576.728.871.469.455.663.783.769.174.365.2

nix:GasDistributionOperations


Regulated
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
Value4.48.716157.056111218124.2126.411
Percentage of RegulatedOperatingRevenueOther13.122.328.738.523.371.228.630.644.436.316.330.925.734.8

us-gaap:CorporateAndOther


Regulated
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value8.07.10.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedOperatingRevenueOther23.818.20.00.00.00.00.00.00.00.00.00.0

us-gaap:RepaymentsOfLongTermDebtAndCapitalSecurities

us-gaap:RepaymentsOfLongTermDebtAndCapitalSecurities


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-31
Value6.35.95.616083.74.13.12.5432.32.15522122795022741041362233.23.42042332.718488.03.95034.29.15.75423427320
Percentage of RepaymentsOfLongTermDebtAndCapitalSecurities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths

us-gaap:RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths


Repayments
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value8500.013500.01502000.0350
Percentage of RepaymentsOfShortTermDebtMaturingInMoreThanThreeMonths100.00.0100.00.0100.0100.00.0100.0

us-gaap:RestructuringReservePeriodIncreaseDecrease

us-gaap:RestructuringReservePeriodIncreaseDecrease


Restructuring
Period End2021-03-31
Value4.6
Percentage of RestructuringReservePeriodIncreaseDecrease100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeBenefitPlan

us-gaap:StockIssuedDuringPeriodSharesEmployeeBenefitPlan


Stock
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
Value96000.0103000.0118000.0130000.0131000.0165000.0165000.0146000.0156000.0164000.0194000.0192000.0232000.0264000.0
Percentage of StockIssuedDuringPeriodSharesEmployeeBenefitPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeBenefitPlan us-gaap:StatementEquityComponents

us-gaap:CommonStock


Stock
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
Value96000.0103000.0118000.0130000.0131000.0165000.0165000.0146000.0156000.0164000.0194000.0192000.0232000.0264000.0
Percentage of StockIssuedDuringPeriodSharesEmployeeBenefitPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans


Stock
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
Value0.0520.0550.0650.0650.060.0460.0480.0510.0520.050.0570.0550.0640.0470.0520.0520.0540.049
Percentage of StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans us-gaap:StatementEquityComponents

us-gaap:CommonStock


Stock
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
Value0.0520.0550.0650.0650.060.0460.0480.0510.0520.050.0570.0550.0640.0470.0520.0520.0540.049
Percentage of StockIssuedDuringPeriodSharesEmployeeStockPurchasePlans100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesNewIssues us-gaap:CapitalUnitsByClass

us-gaap:StockIssuedDuringPeriodSharesNewIssues

nix:SeriesACorporateUnits


Stock
Period End2021-04-19
Value8.625
Percentage of StockIssuedDuringPeriodSharesNewIssues100.0

us-gaap:StockIssuedDuringPeriodSharesNewIssues us-gaap:CapitalUnitsByClass, us-gaap:SubsequentEventType

nix:SeriesACorporateUnits, us-gaap:SubsequentEvent


Stock
Period End2021-04-19
Value8.625
Percentage of StockIssuedDuringPeriodSharesNewIssues100.0

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation


Stock
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
Value0.0510.2120.0040.0020.0320.3470.0530.0010.0380.4260.0620.0050.0740.420.110.02-0.5420.763
Percentage of StockIssuedDuringPeriodSharesShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodSharesShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:CommonStock


Stock
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
Value0.0510.2120.0040.0020.0320.3470.0530.0010.0380.4260.0620.0050.0740.420.110.02-0.5420.763
Percentage of StockIssuedDuringPeriodSharesShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeBenefitPlan

us-gaap:StockIssuedDuringPeriodValueEmployeeBenefitPlan


Stock
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
Value2.42.32.73.03.24.54.54.34.44.44.95.05.76.2
Percentage of StockIssuedDuringPeriodValueEmployeeBenefitPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeBenefitPlan us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
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
Value2.42.32.73.03.24.54.54.34.44.44.95.05.76.2
Percentage of StockIssuedDuringPeriodValueEmployeeBenefitPlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1200000.01300000.01500000.01500000.01400000.01300000.01400000.01500000.01400000.01300000.01300000.01500000.01500000.01200000.01300000.01300000.01300000.01100000.01300000.01300000.01100000.01000000.01100000.01400000.01400000.01200000.01200000.01100000.01100000.0800000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueEmployeeStockPurchasePlan us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value1200000.01300000.01500000.01500000.01400000.01300000.01400000.01500000.01400000.01300000.01300000.01500000.01500000.01200000.01300000.01300000.01300000.01100000.01300000.01300000.01100000.01000000.01100000.01400000.01400000.01200000.01200000.01100000.01100000.0800000.0
Percentage of StockIssuedDuringPeriodValueEmployeeStockPurchasePlan100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueOther

us-gaap:StockIssuedDuringPeriodValueOther


Stock
Period End2021-06-302021-03-312018-12-31
Value0.0-0.3-161.4
Percentage of StockIssuedDuringPeriodValueOther0.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueOther us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312018-12-31
Value0.0-0.3232
Percentage of StockIssuedDuringPeriodValueOther0.0100.0-144.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value4.8-0.55.33.20.4-0.54.73.64.8-2.73.93.34.24.03.74.33.03.94.03.13.510-12.83.82.2118.3166.68.4
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:StockIssuedDuringPeriodValueShareBasedCompensation us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stock
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value4.8-0.55.33.20.4-0.54.73.64.8-2.73.93.34.24.03.74.33.03.94.03.13.510-12.83.82.2118.3166.68.4
Percentage of StockIssuedDuringPeriodValueShareBasedCompensation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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
Value6681747068857467668771586578675756766656507158537910277687310178647086726266867459679374626486
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

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations


Utilities
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
Value36236140837935344435939349552804780365402427383391410424336337354349311561574572529533501498468452455440422394405480407402432457382377439
Percentage of UtilitiesOperatingExpenseMaintenanceAndOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:EntityCommonStockSharesOutstanding

dei:EntityCommonStockSharesOutstanding


Entity
Period End2021-07-262021-04-262021-02-092020-10-26
Value392392391383
Percentage of EntityCommonStockSharesOutstanding100.0100.0100.0100.0

nix:AcceleratedDepreciationAndOtherPropertyDifferences

nix:AcceleratedDepreciationAndOtherPropertyDifferences


Accelerated
Period End2020-12-312019-12-312018-12-312017-12-31
Value2339251624582260
Percentage of AcceleratedDepreciationAndOtherPropertyDifferences100.0100.0100.0100.0

nix:AccruedInsuranceClaimsCurrent

nix:AccruedInsuranceClaimsCurrent


Accrued
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312017-12-31
Value2826222416518423525811412
Percentage of AccruedInsuranceClaimsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:AdditionalObligationToTheDeveloper

nix:AdditionalObligationToTheDeveloper


Additional
Period End2021-03-31
Value6000000.0
Percentage of AdditionalObligationToTheDeveloper100.0

nix:AssetsHeldforSaleTotalCurrentAssets us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

nix:AssetsHeldforSaleTotalCurrentAssets

nix:MassachusettsBusinessDomain


Assets
Period End2020-09-30
Value161
Percentage of AssetsHeldforSaleTotalCurrentAssets100.0

nix:COVID19RelatedCostsRegulatoryAsset dei:LegalEntity

nix:COVID19RelatedCostsRegulatoryAsset

nix:ColumbiaOfMaryland


C
Period End2020-12-31
Value700000.0
Percentage of COVID19RelatedCostsRegulatoryAsset100.0

nix:ColumbiaOfOhio


C
Period End2020-12-31
Value2000000.0
Percentage of COVID19RelatedCostsRegulatoryAsset285.7

nix:ColumbiaOfPennsylvania


C
Period End2020-12-31
Value5400000.0
Percentage of COVID19RelatedCostsRegulatoryAsset771.4

nix:NIPSCO


C
Period End2020-12-31
Value9200000.0
Percentage of COVID19RelatedCostsRegulatoryAsset1314.3

nix:ChangeInAccumulatedOtherComprehensiveIncomeDueToInterimMeasurement us-gaap:RetirementPlanType

nix:ChangeInAccumulatedOtherComprehensiveIncomeDueToInterimMeasurement

us-gaap:PensionPlansDefinedBenefit


Change
Period End2021-03-312020-09-30
Value400000.0200000.0
Percentage of ChangeInAccumulatedOtherComprehensiveIncomeDueToInterimMeasurement100.0100.0

nix:ChangeInRegulatoryAssetsDueToInterimMeasurement us-gaap:RetirementPlanType

nix:ChangeInRegulatoryAssetsDueToInterimMeasurement

us-gaap:PensionPlansDefinedBenefit


Change
Period End2021-03-312020-09-30
Value2100000.01400000.0
Percentage of ChangeInRegulatoryAssetsDueToInterimMeasurement100.0100.0

nix:ChangeToDefinedBenefitPlanNetPeriodicCostsDueToInterimMeasurement us-gaap:RetirementPlanType

nix:ChangeToDefinedBenefitPlanNetPeriodicCostsDueToInterimMeasurement

us-gaap:PensionPlansDefinedBenefit


Change
Period End2021-03-312020-09-30
Value4000000.0-1400000.0
Percentage of ChangeToDefinedBenefitPlanNetPeriodicCostsDueToInterimMeasurement100.0100.0

nix:CoalfiredGeneratingCapacity

nix:CoalfiredGeneratingCapacity


Coalfired
Period End2020-12-31
Value2080.0
Percentage of CoalfiredGeneratingCapacity100.0

nix:ColumbiaOfMarylandCOVIDReliefFunds

nix:ColumbiaOfMarylandCOVIDReliefFunds


Columbia
Period End2021-06-30
Value800000.0
Percentage of ColumbiaOfMarylandCOVIDReliefFunds100.0

nix:CommonDividendsPayableCurrent

nix:CommonDividendsPayableCurrent


Common
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value86868080800.07474740.0700.0
Percentage of CommonDividendsPayableCurrent100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.00.0

nix:CommonStockAggregateSalePrice us-gaap:StatementEquityComponents

nix:CommonStockAggregateSalePrice

nix:AtTheMarketProgram


Common
Period End2021-03-312020-12-312019-12-312018-12-312018-11-012017-05-03
Value750434434500500500
Percentage of CommonStockAggregateSalePrice100.0100.0100.0100.0100.0100.0

nix:CustomerAccountsReceivableBilledLessReserve

nix:CustomerAccountsReceivableBilledLessReserve


Customer
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value323507400291326449466297396692540297477
Percentage of CustomerAccountsReceivableBilledLessReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:CustomerAccountsReceivableUnbilledLessReserve

nix:CustomerAccountsReceivableUnbilledLessReserve


Customer
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value203244327178187233346193179284349154356
Percentage of CustomerAccountsReceivableUnbilledLessReserve100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:DeferredChargesAndOther

nix:DeferredChargesAndOther


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value2602372281621631601631571461348611782
Percentage of DeferredChargesAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities

nix:DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-31
Value287336365406
Percentage of DeferredInvestmentTaxCreditsAndOtherRegulatoryLiabilities100.0100.0100.0100.0

nix:DeferredPayrollTaxes

nix:DeferredPayrollTaxes


Deferred
Period End2020-09-30
Value21
Percentage of DeferredPayrollTaxes100.0

nix:DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental

nix:DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental


Deferred
Period End2020-12-312019-12-312018-12-312017-12-31
Value22252424
Percentage of DeferredTaxAssetsOtherAccruedLiabilitiesEnvironmental100.0100.0100.0100.0

nix:DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeOrRegulatoryAssetOrLiability us-gaap:RetirementPlanType

nix:DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeOrRegulatoryAssetOrLiability

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value10612.827
Percentage of DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeOrRegulatoryAssetOrLiability100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value-141.3-61.183-100.0
Percentage of DefinedBenefitPlanAmountsRecognizedInOtherComprehensiveIncomeOrRegulatoryAssetOrLiability-1345.7-99.52992.9-367.6

nix:DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:RetirementPlanType

nix:DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-31
Value240
Percentage of DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems100.0

us-gaap:FairValueInputsLevel1, us-gaap:FairValueMeasurementsRecurring, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-31
Value231
Percentage of DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems96.0

nix:DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:RetirementPlanType

us-gaap:FairValueInputsLevel2, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value936971693476
Percentage of DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems388.90.00.00.0

nix:DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value286261216262
Percentage of DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems119.00.00.00.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value2110207318602155
Percentage of DefinedBenefitPlanFairValueOfPlanAssetsBeforePendingItems876.90.00.00.0

nix:DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanType

nix:DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets

nix:DomesticEquities, us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value38.00.3590.3640.366
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets100.0100.0100.0100.0

nix:DomesticEquities, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value21.00.2150.190.323
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets55.359.952.288.3

nix:InternationalEquities, us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value16.80.1560.0810.152
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets44.243.522.341.5

nix:InternationalEquities, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value10.90.0990.0890.162
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets28.727.624.544.3

nix:RealEstateAndPrivateEquityAndHedgeFunds, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value2.50.0260.0280.023
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets6.67.27.76.3

us-gaap:CashAndCashEquivalents, us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value2.60.0280.0230.034
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets6.87.86.39.3

us-gaap:CashAndCashEquivalents, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value4.60.0180.0280.039
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets12.15.07.710.7

us-gaap:DebtSecurities, us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value42.60.4570.5320.448
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets112.1127.3146.2122.4

us-gaap:DebtSecurities, us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value61.00.6420.6650.453
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets160.5178.8182.7123.8

nix:DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value100.01.01.01.0
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets263.2278.6274.7273.2

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2020-12-312019-12-312018-12-312017-12-31
Value100.01.01.01.0
Percentage of DefinedBenefitPlanTargetAllocationPercentageOfTotalAssets263.2278.6274.7273.2

nix:Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilities us-gaap:RetirementPlanType

nix:Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilities

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value1061075661
Percentage of Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilities100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilitiesus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value497655764695
Percentage of Definedbenefitplanrecognizedinaccumulatedothercomprehensiveincomenetgainsorlossesbeforeincometaxorregulatoryassetsorliabilities468.0608.91357.71138.1

nix:DepositaryStockLiquidationPreference us-gaap:StatementClassOfStock

nix:DepositaryStockLiquidationPreference

us-gaap:SeriesBPreferredStock


Depositary
Period End2020-12-31
Value25.0
Percentage of DepositaryStockLiquidationPreference100.0

nix:EnergyCommodityContractsFutureMinimumPaymentsDue

nix:EnergyCommodityContractsFutureMinimumPaymentsDue


Energy
Period End2020-12-312019-12-31
Value4295
Percentage of EnergyCommodityContractsFutureMinimumPaymentsDue100.0100.0

nix:EnergyCommodityContractsFutureMinimumPaymentsDueNextTwelveMonths

nix:EnergyCommodityContractsFutureMinimumPaymentsDueNextTwelveMonths


Energy
Period End2020-12-31
Value42
Percentage of EnergyCommodityContractsFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:ExchangeGasPayable

nix:ExchangeGasPayable


Exchange
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value34254846271859544215855859
Percentage of ExchangeGasPayable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:ExchangeGasReceivable

nix:ExchangeGasReceivable


Exchange
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value31533424173948304172883745
Percentage of ExchangeGasReceivable100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:ExpectedFutureObligationToTheDeveloper

nix:ExpectedFutureObligationToTheDeveloper


Expected
Period End2020-12-31
Value6000000.0
Percentage of ExpectedFutureObligationToTheDeveloper100.0

nix:FinanceLeasesFutureMinimumPaymentsInterestIncludedinPayments

nix:FinanceLeasesFutureMinimumPaymentsInterestIncludedinPayments


Finance
Period End2020-12-31
Value69
Percentage of FinanceLeasesFutureMinimumPaymentsInterestIncludedinPayments100.0

nix:FutureRFPCapacity

nix:FutureRFPCapacity


Future
Period End2020-09-30
Value1400.0
Percentage of FutureRFPCapacity100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDue

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDue


Interest
Period End2020-12-31
Value6046
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDue100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueNextTwelveMonths

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueNextTwelveMonths


Interest
Period End2020-12-31
Value336
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueThereafter

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueThereafter


Interest
Period End2020-12-31
Value4372
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueThereafter100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFiveYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFiveYears


Interest
Period End2020-12-31
Value334
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFiveYears100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFourYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFourYears


Interest
Period End2020-12-31
Value334
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinFourYears100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinThreeYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinThreeYears


Interest
Period End2020-12-31
Value334
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinThreeYears100.0

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinTwoYears

nix:InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinTwoYears


Interest
Period End2020-12-31
Value335
Percentage of InterestPaymentsonLongtermDebtFutureMinimumPaymentsDueinTwoYears100.0

nix:LegalAndEnvironmentalReserves

nix:LegalAndEnvironmentalReserves


Legal
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value17211720202118182032
Percentage of LegalAndEnvironmentalReserves100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:LiabilitiesHeldforSaleLongTermDebt us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

nix:LiabilitiesHeldforSaleLongTermDebt

nix:MassachusettsBusinessDomain


Liabilities
Period End2020-09-30
Value41
Percentage of LiabilitiesHeldforSaleLongTermDebt100.0

nix:LiabilitiesHeldforSaleTotalCurrentLiabilities us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

nix:LiabilitiesHeldforSaleTotalCurrentLiabilities

nix:MassachusettsBusinessDomain


Liabilities
Period End2020-09-30
Value60
Percentage of LiabilitiesHeldforSaleTotalCurrentLiabilities100.0

nix:LiabilityForEstimatedRemediationCosts us-gaap:LossContingenciesByNatureOfContingency

nix:LiabilityForEstimatedRemediationCosts

nix:MgpSites


Liability
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value8784858892861021031059697103106
Percentage of LiabilityForEstimatedRemediationCosts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:LongtermDebtFutureMinimumPaymentsDue

nix:LongtermDebtFutureMinimumPaymentsDue


Longterm
Period End2020-12-31
Value9135
Percentage of LongtermDebtFutureMinimumPaymentsDue100.0

nix:LongtermDebtFutureMinimumPaymentsDueThereafter

nix:LongtermDebtFutureMinimumPaymentsDueThereafter


Longterm
Period End2020-12-31
Value7845
Percentage of LongtermDebtFutureMinimumPaymentsDueThereafter100.0

nix:LongtermDebtFutureMinimumPaymentsDueinFiveYears

nix:LongtermDebtFutureMinimumPaymentsDueinFiveYears


Longterm
Period End2020-12-31
Value1260
Percentage of LongtermDebtFutureMinimumPaymentsDueinFiveYears100.0

nix:LongtermDebtFutureMinimumPaymentsDueinTwoYears

nix:LongtermDebtFutureMinimumPaymentsDueinTwoYears


Longterm
Period End2020-12-31
Value30
Percentage of LongtermDebtFutureMinimumPaymentsDueinTwoYears100.0

nix:LongtermLeaseLiability

nix:LongtermLeaseLiability


Longterm
Period End2020-12-31
Value201
Percentage of LongtermLeaseLiability100.0

nix:NameplateCapacity nix:ConstructionCompletion, nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType

nix:NameplateCapacity

nix:A2022, nix:BuildTransferAgreement, us-gaap:SubsequentEvent


Nameplate
Period End2020-10-16
Value265.0
Percentage of NameplateCapacity100.0

nix:A2023, nix:BuildTransferAgreement, us-gaap:SubsequentEvent


Nameplate
Period End2020-10-16
Value635.0
Percentage of NameplateCapacity239.6

nix:NameplateCapacity nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType

nix:BuildTransferAgreement, us-gaap:SubsequentEvent


Nameplate
Period End2020-10-16
Value900.0
Percentage of NameplateCapacity339.6

nix:NetAssetValueExcludedFromFairValueByInput

nix:NetAssetValueExcludedFromFairValueByInput


Net
Period End2020-12-312019-12-312018-12-312017-12-31
Value9188607671032
Percentage of NetAssetValueExcludedFromFairValueByInput100.0100.0100.0100.0

nix:NetAssetValueExcludedFromFairValueByInput us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FinancialInstrument

nix:InternationalEquities, nix:CommingledFunds


Net
Period End2020-12-312019-12-312018-12-312017-12-31
Value200168122265
Percentage of NetAssetValueExcludedFromFairValueByInput21.919.515.925.7

nix:ShortTermMoneyMarkets, nix:CommingledFunds


Net
Period End2020-12-312019-12-312018-12-312017-12-31
Value86222343
Percentage of NetAssetValueExcludedFromFairValueByInput9.42.63.14.2

nix:UnitedStatesEquities, nix:CommingledFunds


Net
Period End2020-12-312019-12-312018-12-312017-12-31
Value293318255478
Percentage of NetAssetValueExcludedFromFairValueByInput32.037.033.346.4

us-gaap:FixedIncomeFunds, nix:CommingledFunds


Net
Period End2020-12-312019-12-312018-12-312017-12-31
Value337351365244
Percentage of NetAssetValueExcludedFromFairValueByInput36.840.947.723.7

nix:NetProceedsFromSale

nix:NetProceedsFromSale


Net
Period End2020-10-09
Value1113
Percentage of NetProceedsFromSale100.0

nix:NetProceedsFromSale us-gaap:CapitalUnitsByClass

nix:SeriesACorporateUnits


Net
Period End2021-04-19
Value835
Percentage of NetProceedsFromSale0.0

nix:NetProceedsFromSale us-gaap:CapitalUnitsByClass, us-gaap:SubsequentEventType

nix:SeriesACorporateUnits, us-gaap:SubsequentEvent


Net
Period End2021-04-19
Value835
Percentage of NetProceedsFromSale0.0

nix:NetProceedsFromSale us-gaap:SubsequentEventType

us-gaap:SubsequentEvent


Net
Period End2020-10-09
Value1112
Percentage of NetProceedsFromSale100.0

nix:NumberOfWasteDisposalSitesIdentifiedByProgram us-gaap:LossContingenciesByNatureOfContingency

nix:NumberOfWasteDisposalSitesIdentifiedByProgram

nix:MgpSites


Number
Period End2021-06-302021-03-312020-12-312020-09-30
Value54.054.054.063.0
Percentage of NumberOfWasteDisposalSitesIdentifiedByProgram100.0100.0100.0100.0

nix:NumberOfWasteDisposalSitesIdentifiedByProgram us-gaap:LossContingenciesByNatureOfContingency, us-gaap:SubsequentEventType

nix:MgpSites, us-gaap:SubsequentEvent


Number
Period End2020-10-09
Value54.0
Percentage of NumberOfWasteDisposalSitesIdentifiedByProgram0.0

nix:ObligationToTheDeveloper

nix:ObligationToTheDeveloper


Obligation
Period End2021-06-302021-03-312020-12-31
Value6.06.069
Percentage of ObligationToTheDeveloper100.0100.0100.0

nix:OperatingLeasesFutureMinimumPayamentsInterestIncludedinPayments

nix:OperatingLeasesFutureMinimumPayamentsInterestIncludedinPayments


Operating
Period End2020-12-31
Value7800000.0
Percentage of OperatingLeasesFutureMinimumPayamentsInterestIncludedinPayments100.0

nix:OtherLiabilitiesFutureMinimumPaymentsDue

nix:OtherLiabilitiesFutureMinimumPaymentsDue


Other
Period End2020-12-31
Value116
Percentage of OtherLiabilitiesFutureMinimumPaymentsDue100.0

nix:OtherLiabilitiesFutureMinimumPaymentsDueNextTwelveMonths

nix:OtherLiabilitiesFutureMinimumPaymentsDueNextTwelveMonths


Other
Period End2020-12-31
Value26
Percentage of OtherLiabilitiesFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:OtherLiabilitiesFutureMinimumPaymentsDueinThreeYears

nix:OtherLiabilitiesFutureMinimumPaymentsDueinThreeYears


Other
Period End2020-12-31
Value90
Percentage of OtherLiabilitiesFutureMinimumPaymentsDueinThreeYears100.0

nix:OtherLiabilitiesFutureMinimumPaymentsDueinTwoYears

nix:OtherLiabilitiesFutureMinimumPaymentsDueinTwoYears


Other
Period End2020-12-31
Value800000.0
Percentage of OtherLiabilitiesFutureMinimumPaymentsDueinTwoYears100.0

nix:OtherRegulatoryAssets

nix:OtherRegulatoryAssets


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value331381375309
Percentage of OtherRegulatoryAssets100.0100.0100.0100.0

nix:PlantAndEquipmentAssociatedWithSchahferGeneratingStationRetirement

nix:PlantAndEquipmentAssociatedWithSchahferGeneratingStationRetirement


Plant
Period End2021-06-302021-03-312020-12-312020-09-30
Value823861903903
Percentage of PlantAndEquipmentAssociatedWithSchahferGeneratingStationRetirement100.0100.0100.0100.0

nix:PreferredDividendsPayableCurrent

nix:PreferredDividendsPayableCurrent


Preferred
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value8.119198.1190.0198.2190.0110.0
Percentage of PreferredDividendsPayableCurrent100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.00.0

nix:PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyAtCostLessAccumulatedDepreciation

nix:PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyAtCostLessAccumulatedDepreciation


Public
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value89489418181818181917286
Percentage of PublicUtilitiesPropertyPlantAndEquipmentOtherPropertyAtCostLessAccumulatedDepreciation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceNet

nix:PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceNet


Public
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value15184148781556816893164621611515722155221515714073
Percentage of PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:PurchaseContractLiability

nix:PurchaseContractLiability


Purchase
Period End2021-06-302021-04-19
Value161168
Percentage of PurchaseContractLiability100.0100.0

nix:ReasonablyPossibleRemediationCostsVarianceFromReserve us-gaap:LossContingenciesByNatureOfContingency

nix:ReasonablyPossibleRemediationCostsVarianceFromReserve

nix:MgpSites


Reasonably
Period End2021-06-302021-03-312020-12-312020-09-30
Value17202020
Percentage of ReasonablyPossibleRemediationCostsVarianceFromReserve100.0100.0100.0100.0

nix:RegulatoryNetCapitalExpendituresIncludedInFiling dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding

nix:RegulatoryNetCapitalExpendituresIncludedInFiling

nix:ColumbiaOfPennsylvania, nix:DSICQ32020


Regulatory
Period End2020-09-18
Value85
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling100.0

nix:ColumbiaOfVirginia, nix:A2021SAVE


Regulatory
Period End2020-07-24
Value46
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:NIPSCOElectric, nix:TDSIC7


Regulatory
Period End2020-09-29
Value122
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:NIPSCOGas, nix:TDSIC1


Regulatory
Period End2020-08-25
Value26
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:RegulatoryNetCapitalExpendituresIncludedInFiling dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:SubsequentEventType

nix:ColumbiaOfKentucky, nix:A2021SMRP, us-gaap:SubsequentEvent


Regulatory
Period End2020-10-15
Value50
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:ColumbiaOfMaryland, nix:A2021STRIDE, us-gaap:SubsequentEvent


Regulatory
Period End2020-10-29
Value16
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:ColumbiaOfVirginia, nix:A2021SAVE, us-gaap:SubsequentEvent


Regulatory
Period End2020-07-24
Value46
Percentage of RegulatoryNetCapitalExpendituresIncludedInFiling0.0

nix:SeasonalLimit us-gaap:FinancialInstrument

nix:SeasonalLimit

nix:AccountsReceivableProgram


Seasonal
Period End2021-06-302021-03-312020-12-312020-09-30
Value340510380275
Percentage of SeasonalLimit100.0100.0100.0100.0

nix:SecurityInterestAndOtherSubsetOfAsset

nix:SecurityInterestAndOtherSubsetOfAsset


Security
Period End2020-12-31
Value150
Percentage of SecurityInterestAndOtherSubsetOfAsset100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDue

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDue


Service
Period End2020-12-31
Value240
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDue100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths


Service
Period End2020-12-31
Value74
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFiveYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFiveYears


Service
Period End2020-12-31
Value22
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFiveYears100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFourYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFourYears


Service
Period End2020-12-31
Value30
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinFourYears100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinThreeYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinThreeYears


Service
Period End2020-12-31
Value38
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinThreeYears100.0

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinTwoYears

nix:ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinTwoYears


Service
Period End2020-12-31
Value74
Percentage of ServiceObligationsITServiceObligationsFutureMinimumPaymentsDueinTwoYears100.0

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue


Service
Period End2020-12-31
Value12
Percentage of ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue100.0

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue us-gaap:SubsequentEventType

us-gaap:SubsequentEvent


Service
Period End2021-02-09
Value12
Percentage of ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDue0.0

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths


Service
Period End2020-12-31
Value12
Percentage of ServiceObligationsOtherServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue


Service
Period End2020-12-31
Value1495
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue us-gaap:SubsequentEventType

us-gaap:SubsequentEvent


Service
Period End2021-02-01
Value638
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDue0.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths


Service
Period End2020-12-31
Value468
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueNextTwelveMonths100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueThereafter

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueThereafter


Service
Period End2020-12-31
Value141
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueThereafter100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFiveYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFiveYears


Service
Period End2020-12-31
Value56
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFiveYears100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFourYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFourYears


Service
Period End2020-12-31
Value150
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinFourYears100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinThreeYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinThreeYears


Service
Period End2020-12-31
Value256
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinThreeYears100.0

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinTwoYears

nix:ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinTwoYears


Service
Period End2020-12-31
Value422
Percentage of ServiceObligationsPipelineServiceObligationsFutureMinimumPaymentsDueinTwoYears100.0

nix:ShorttermLeaseLiability

nix:ShorttermLeaseLiability


Shortterm
Period End2020-12-31
Value33
Percentage of ShorttermLeaseLiability100.0

nix:StorageCapacity nix:PurchaseAndServiceObligations

nix:StorageCapacity

nix:PurchasePowerAgreementsJun2020


Storage
Period End2020-09-30
Value30.0
Percentage of StorageCapacity100.0

nix:StorageCapacity nix:PurchaseAndServiceObligations, us-gaap:SubsequentEventType

nix:BuildTransferAgreement, us-gaap:SubsequentEvent


Storage
Period End2020-10-16
Value135.0
Percentage of StorageCapacity0.0

nix:TotalExpectedContributions

nix:TotalExpectedContributions


Total
Period End2020-12-31
Value170
Percentage of TotalExpectedContributions100.0

nix:TotalFutureContractualObligationsDue

nix:TotalFutureContractualObligationsDue


Total
Period End2020-12-31
Value17401
Percentage of TotalFutureContractualObligationsDue100.0

nix:TotalFutureContractualObligationsDueNextTwelveMonths

nix:TotalFutureContractualObligationsDueNextTwelveMonths


Total
Period End2020-12-31
Value1005
Percentage of TotalFutureContractualObligationsDueNextTwelveMonths100.0

nix:TotalFutureContractualObligationsDueThereafter

nix:TotalFutureContractualObligationsDueThereafter


Total
Period End2020-12-31
Value12511
Percentage of TotalFutureContractualObligationsDueThereafter100.0

nix:TotalFutureContractualObligationsDueinFiveYears

nix:TotalFutureContractualObligationsDueinFiveYears


Total
Period End2020-12-31
Value1692
Percentage of TotalFutureContractualObligationsDueinFiveYears100.0

nix:TotalFutureContractualObligationsDueinFourYears

nix:TotalFutureContractualObligationsDueinFourYears


Total
Period End2020-12-31
Value540
Percentage of TotalFutureContractualObligationsDueinFourYears100.0

nix:TotalFutureContractualObligationsDueinThreeYears

nix:TotalFutureContractualObligationsDueinThreeYears


Total
Period End2020-12-31
Value751
Percentage of TotalFutureContractualObligationsDueinThreeYears100.0

nix:TotalFutureContractualObligationsDueinTwoYears

nix:TotalFutureContractualObligationsDueinTwoYears


Total
Period End2020-12-31
Value900
Percentage of TotalFutureContractualObligationsDueinTwoYears100.0

nix:TotalFutureMinimumLeasePaymentsDue

nix:TotalFutureMinimumLeasePaymentsDue


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value312405409411399368
Percentage of TotalFutureMinimumLeasePaymentsDue100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueNextTwelveMonths

nix:TotalFutureMinimumLeasePaymentsDueNextTwelveMonths


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value444237363534
Percentage of TotalFutureMinimumLeasePaymentsDueNextTwelveMonths100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueThereafter

nix:TotalFutureMinimumLeasePaymentsDueThereafter


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value152233247250246226
Percentage of TotalFutureMinimumLeasePaymentsDueThereafter100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueinFiveYears

nix:TotalFutureMinimumLeasePaymentsDueinFiveYears


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value192627272522
Percentage of TotalFutureMinimumLeasePaymentsDueinFiveYears100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueinFourYears

nix:TotalFutureMinimumLeasePaymentsDueinFourYears


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value253029292826
Percentage of TotalFutureMinimumLeasePaymentsDueinFourYears100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueinThreeYears

nix:TotalFutureMinimumLeasePaymentsDueinThreeYears


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value333532323128
Percentage of TotalFutureMinimumLeasePaymentsDueinThreeYears100.0100.0100.0100.0100.0100.0

nix:TotalFutureMinimumLeasePaymentsDueinTwoYears

nix:TotalFutureMinimumLeasePaymentsDueinTwoYears


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value373633333129
Percentage of TotalFutureMinimumLeasePaymentsDueinTwoYears100.0100.0100.0100.0100.0100.0

nix:TotalLeaseLiability

nix:TotalLeaseLiability


Total
Period End2020-12-312019-12-312019-09-302019-06-302019-03-31
Value235266258256252
Percentage of TotalLeaseLiability100.0100.0100.0100.0100.0

nix:Totalleasedassets

nix:Totalleasedassets


Totalleasedassets
Period End2020-12-312019-12-31
Value216243
Percentage of Totalleasedassets100.0100.0

nix:TradeReceivablesAvailableForTransfer

nix:TradeReceivablesAvailableForTransfer


Trade
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value630607421467593569375468742694410635
Percentage of TradeReceivablesAvailableForTransfer100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:TradeReceivablesNotTransferred

nix:TradeReceivablesNotTransferred


Trade
Period End2021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value630607190153133215115148242295145298
Percentage of TradeReceivablesNotTransferred100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:TradeReceivablesTransferredNet

nix:TradeReceivablesTransferredNet


Trade
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value231313459353260320500399265336
Percentage of TradeReceivablesTransferredNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

nix:UndiscountedExcessAmount

nix:UndiscountedExcessAmount


Undiscounted
Period End2020-12-31
Value77
Percentage of UndiscountedExcessAmount100.0

nix:VIENetAssets

nix:VIENetAssets


V
Period End2021-06-302021-03-312020-12-31
Value169170156
Percentage of VIENetAssets100.0100.0100.0

nix:WindPowerPurchaseAgreementCapacity

nix:WindPowerPurchaseAgreementCapacity


Wind
Period End2020-12-31
Value500.0
Percentage of WindPowerPurchaseAgreementCapacity100.0

nix:WindPowerPurchaseAgreementPurchasePercentage

nix:WindPowerPurchaseAgreementPurchasePercentage


Wind
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302019-01-01
Value100.0100.0100.0100.01.01.0
Percentage of WindPowerPurchaseAgreementPurchasePercentage100.0100.0100.0100.0100.0100.0

nix:WorkingCapitalAdjustment

nix:WorkingCapitalAdjustment


Working
Period End2020-09-30
Value5300000.0
Percentage of WorkingCapitalAdjustment100.0

us-gaap:AccountsReceivableGrossCurrent

us-gaap:AccountsReceivableGrossCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-31
Value605848843560577736876
Percentage of AccountsReceivableGrossCurrent100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccrualForEnvironmentalLossContingencies

us-gaap:AccrualForEnvironmentalLossContingencies


Accrual
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302010-12-31
Value939092939791104107108991011071091091111121151091111161201221231251361281281301321351431491561551601621681681731057979
Percentage of AccrualForEnvironmentalLossContingencies100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccruedInsuranceNoncurrent

us-gaap:AccruedInsuranceNoncurrent


Accrued
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value848285828185828484818683808986858287
Percentage of AccruedInsuranceNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AccumulatedDeferredInvestmentTaxCredit

us-gaap:AccumulatedDeferredInvestmentTaxCredit


Accumulated
Period End2020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value8.89.19.49.710101011111112121212131313141414151616171819202021222324252627293031323339
Percentage of AccumulatedDeferredInvestmentTaxCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent


Allowance
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312009-12-31
Value4153523931201915283121132428181726322319313220203840251829342320323124314245302942553739
Percentage of AllowanceForDoubtfulAccountsReceivableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetRetirementObligation

us-gaap:AssetRetirementObligation


Asset
Period End2020-12-312019-12-312018-12-31
Value495416352
Percentage of AssetRetirementObligation100.0100.0100.0

us-gaap:AssetRetirementObligationsNoncurrent

us-gaap:AssetRetirementObligationsNoncurrent


Asset
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302009-12-31
Value437479477424447435416373367358352346334269268268267261262272257253254181204160159175178176174175167165160152149148146140138140138134136138
Percentage of AssetRetirementObligationsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetRetirementObligationsNoncurrent dei:LegalEntity

nix:Rosewater


Asset
Period End2021-06-302021-03-312020-12-31
Value5.65.55.5
Percentage of AssetRetirementObligationsNoncurrent1.31.11.2

us-gaap:AssetsFairValueDisclosure

us-gaap:AssetsFairValueDisclosure


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value178172184182179172158151150151162201155
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsFairValueDisclosure us-gaap:FairValueByFairValueHierarchyLevel

us-gaap:FairValueInputsLevel2


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value178172184182179172158151150151162201155
Percentage of AssetsFairValueDisclosure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent


Assets
Period End2020-09-302020-06-302020-03-312019-12-312015-12-312015-09-302014-12-312013-12-312013-09-302013-06-302013-03-312012-12-312011-12-312010-12-312009-12-31
Value1565154216550.00.00.03410.00.00.00.026260.01.4
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent100.0100.0100.00.00.00.0100.00.00.00.00.0100.0100.00.0100.0

us-gaap:AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent us-gaap:IncomeStatementBalanceSheetAndAdditionalDisclosuresByDisposalGroupsIncludingDiscontinuedOperations

nix:MassachusettsBusinessDomain


Assets
Period End2020-09-302020-06-302020-03-31
Value156515421655
Percentage of AssetsOfDisposalGroupIncludingDiscontinuedOperationCurrent100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value6000000.05500000.08000000.07400000.07100000.02900000.04300000.04300000.03500000.01400000.0500000.0400000.0900000.02800000.03100000.02100000.0400000.01000000.0900000.02100000.01300000.0
Percentage of AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax us-gaap:FinancialInstrument

us-gaap:CorporateDebtSecurities


Available
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302017-12-31
Value5800000.05300000.07700000.07000000.0