MGEE


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

Table of contents



us-gaap:CommonStockValue
us-gaap:StatementEquityComponents
us-gaap:SharesIssued

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareBasicAndDiluted

us-gaap:AllocatedShareBasedCompensationExpense
us-gaap:PlanName
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:CostOfRevenue

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic
dei:LegalEntity

us-gaap:IncomeTaxExpenseBenefit
dei:LegalEntity

us-gaap:InterestIncomeExpenseNet
dei:LegalEntity

us-gaap:NetIncomeLoss
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:StatementEquityComponents
dei:LegalEntity
us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

us-gaap:NonoperatingIncomeExpense
dei:LegalEntity

us-gaap:OperatingIncomeLoss
dei:LegalEntity

us-gaap:ProfitLoss
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:RegulatedAndUnregulatedOperatingRevenue
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
dei:LegalEntity, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ProductOrService
us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax
us-gaap:ProductOrService, us-gaap:StatementBusinessSegments
us-gaap:StatementBusinessSegments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:Revenues

us-gaap:Assets
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidatedEntities
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:LiabilitiesAndStockholdersEquity
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:StockholdersEquity
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents

us-gaap:AssetsCurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:CashAndCashEquivalentsAtCarryingValue
dei:LegalEntity
us-gaap:ConsolidatedEntities

us-gaap:AccountsReceivableNetCurrent
dei:LegalEntity

us-gaap:OtherAssetsCurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:AssetsNoncurrent

us-gaap:ConstructionInProgressGross
dei:LegalEntity
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlant
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

us-gaap:PropertyPlantAndEquipmentNet
dei:LegalEntity
us-gaap:BalanceSheetLocation
us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherAssetsNoncurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities

us-gaap:AccountsPayableCurrent
dei:LegalEntity

us-gaap:LiabilitiesCurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:LongTermDebtCurrent
dei:LegalEntity
us-gaap:BalanceSheetLocation
us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherLiabilitiesCurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities

us-gaap:LiabilitiesNoncurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
dei:LegalEntity
us-gaap:LongTermDebt

us-gaap:LongTermDebtNoncurrent
dei:LegalEntity

us-gaap:DeferredIncomeTaxLiabilitiesNet
dei:LegalEntity
us-gaap:ConsolidatedEntities

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent
dei:LegalEntity
us-gaap:RetirementPlanType
dei:LegalEntity
us-gaap:MinorityInterest

us-gaap:OtherLiabilitiesNoncurrent
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:BalanceSheetLocation
us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:StockholdersEquity
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:StatementEquityComponents
dei:LegalEntity
us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest
dei:LegalEntity, us-gaap:StatementEquityComponents
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:CommonStockValue

us-gaap:AdditionalPaidInCapital
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:CommonStocksIncludingAdditionalPaidInCapital

us-gaap:RetainedEarningsAccumulatedDeficit
dei:LegalEntity
us-gaap:ConsolidatedEntities
dei:LegalEntity
us-gaap:MinorityInterest
dei:LegalEntity
us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect
dei:LegalEntity

us-gaap:DeferredIncomeTaxExpenseBenefit
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInOperatingActivities
dei:LegalEntity

us-gaap:NetIncomeLoss
dei:LegalEntity
dei:LegalEntity, us-gaap:ConsolidationItems
dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments
us-gaap:StatementEquityComponents

us-gaap:ProfitLoss
dei:LegalEntity
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:NetCashProvidedByUsedInInvestingActivities
dei:LegalEntity

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment
dei:LegalEntity

us-gaap:NetCashProvidedByUsedInFinancingActivities
dei:LegalEntity

us-gaap:ProceedsFromIssuanceOfLongTermDebt
dei:LegalEntity

us-gaap:RepaymentsOfLongTermDebt
dei:LegalEntity

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:EffectiveIncomeTaxRateContinuingOperations
dei:LegalEntity
us-gaap:AwardType, us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
us-gaap:AwardType, us-gaap:PlanName, us-gaap:SubsequentEventType
us-gaap:PlanName

us-gaap:DeferredTaxLiabilities
dei:LegalEntity

us-gaap:DeferredTaxAssetsNet
dei:LegalEntity

us-gaap:UnrecognizedTaxBenefits

us-gaap:DeferredTaxAssetsValuationAllowance
dei:LegalEntity

us-gaap:ProceedsFromRepaymentsOfShortTermDebt
dei:LegalEntity
us-gaap:InvestmentType
mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMinimumAnnualRateCompoundedMonthly
us-gaap:InvestmentType
mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMonthlyCompoundingRate

mgee:DeferredSavingsFromCurrentYearEmployeeBenefitCosts

mgee:DefinedBenefitPlanDeferredNetPeriodicBenefitCosts
us-gaap:DerivativeInstrumentRisk
mgee:DerivativeNonmonetaryNotionalAmountDecathermMeasure
us-gaap:DerivativeInstrumentRisk
mgee:DerivativeNonmonetaryNotionalAmountPowerMeasure
us-gaap:BalanceSheetLocation
mgee:DerivativeRealizedGainLossDeferred
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
mgee:EquityMethodInvestmentSummarizedFinancialInformationInterestIncomeExpense
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
mgee:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLossBeforeTaxes
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
mgee:EquityMethodInvestmentSummarizedFinancialInformationOtherIncomeExpense
us-gaap:IncomeTaxAuthority
mgee:ExcessDeferredTaxIncomeStatementEffect
us-gaap:Range
mgee:FairValueInputsCounterpartyFuelMixInternalGeneration
us-gaap:Range
mgee:FairValueInputsCounterpartyFuelMixPurchasedPower

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOffPeak

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOnPeak

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets

mgee:InterestExpenseAndOtherIncomeNet
dei:LegalEntity
mgee:PaymentsForDistributionsToParentFromNoncontrollingInterest

mgee:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity
us-gaap:JointlyOwnedUtilityPlant

mgee:UtilitiesOperatingExpenseCostOfGasSold
dei:LegalEntity

us-gaap:AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs

us-gaap:CapitalExpendituresIncurredButNotYetPaid
dei:LegalEntity

us-gaap:CommonStockDividendsPerShareCashPaid
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAmortizationOfTransitionAssetObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanInterestCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanServiceCost
us-gaap:BalanceSheetLocation
us-gaap:DerivativeGainLossOnDerivativeNet
us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeNonmonetaryNotionalAmountEnergyMeasure

us-gaap:DividendsCommonStockCash
us-gaap:StatementEquityComponents

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationDeductionsOther
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment
dei:LegalEntity

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsOther
dei:LegalEntity

us-gaap:EquityMethodInvestmentDividendsOrDistributions
dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
us-gaap:IncomeStatementLocation

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements

us-gaap:IncomeLossFromEquityMethodInvestments
dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
us-gaap:ConsolidationItems
us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:IncreaseDecreaseInOtherCurrentAssets
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherCurrentLiabilities
dei:LegalEntity

us-gaap:IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet
dei:LegalEntity

us-gaap:OtherNoncashIncomeExpense
dei:LegalEntity

us-gaap:PaymentsForProceedsFromOtherInvestingActivities
dei:LegalEntity

us-gaap:PaymentsToAcquireInterestInSubsidiariesAndAffiliates
dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:SubsequentEventType

us-gaap:PensionAndOtherPostretirementBenefitContributions
dei:LegalEntity

us-gaap:PensionAndOtherPostretirementBenefitExpense
dei:LegalEntity
dei:LegalEntity
us-gaap:ProceedsFromContributionsFromParent
dei:LegalEntity, us-gaap:StatementEquityComponents

us-gaap:ProceedsFromIssuanceOfCommonStock
us-gaap:StatementEquityComponents

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities
dei:LegalEntity

us-gaap:ProvisionForDoubtfulAccounts
dei:LegalEntity
dei:LegalEntity, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesApprovedEquityCapitalStructurePercentage
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesApprovedRateIncreaseDecreasePercentage
dei:LegalEntity, us-gaap:RegulatoryAgency
us-gaap:PublicUtilitiesApprovedReturnOnEquityPercentage
dei:LegalEntity, us-gaap:PublicUtilitiesRegulatoryProceeding, us-gaap:RegulatoryAgency, us-gaap:SubsequentEventType
us-gaap:PublicUtilitiesRequestedRateIncreaseDecreasePercentage

us-gaap:RegulatedOperatingRevenueElectricNonNuclear
dei:LegalEntity

us-gaap:RegulatedOperatingRevenueGas
dei:LegalEntity
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty
us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid

us-gaap:StockIssuedDuringPeriodSharesNewIssues
us-gaap:StatementEquityComponents

us-gaap:StockholdersEquityOther
us-gaap:StatementEquityComponents
us-gaap:BalanceSheetLocation
us-gaap:UnrealizedGainLossOnDerivatives

us-gaap:UtilitiesOperatingExpense
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseDepreciationAndAmortization
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseFuelUsed
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations
dei:LegalEntity

us-gaap:UtilitiesOperatingExpensePurchasedPower
dei:LegalEntity

us-gaap:UtilitiesOperatingExpenseTaxes
dei:LegalEntity

dei:EntityCommonStockSharesOutstanding

mgee:AccountsReceivableLatePaymentChargeOnUnpaidReceivablesSuspended

mgee:AccruedInterestAndTaxes
dei:LegalEntity

mgee:Accruedinterestandtaxes
dei:LegalEntity

mgee:CapitalizedComputerSoftwareHostingAgreementAccumulatedAmortization

mgee:CapitalizedComputerSoftwareHostingAgreementNet
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
mgee:CommercialPaperFairValueDisclosure
us-gaap:FairValueByMeasurementBasis
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
mgee:DeferredCompensationFairValueDisclosure
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency

mgee:DeferredTaxAssetsAccruedExpenses
dei:LegalEntity

mgee:DeferredTaxAssetsLeases
dei:LegalEntity

mgee:DeferredTaxLiabilitiesDeductiblePrepayments
dei:LegalEntity

mgee:DeferredTaxLiabilitiesEquityMethodInvestments

mgee:DeferredTaxLiabilitiesLeases
dei:LegalEntity

mgee:DeferredTaxLiabilitiesPensionAndOtherPostretirementBenefits
dei:LegalEntity

mgee:Deferredfuelrulesmonitoredcosts
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsfivefiscalyearsthereafter
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsnexttwelvemonths
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsyearfive
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsyearfour
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsyearthree
us-gaap:RetirementPlanType
mgee:Definedbenefitplanexpectednetfuturebenefitpaymentsyeartwo
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName
mgee:EquityMethodInvestmentSummarizedFinancialInformationLongTermDebt
us-gaap:AwardType, us-gaap:PlanName
mgee:FairValueOfNonvestedAward
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
mgee:JointlyOwnedUtilityPlantPlantCapacity
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
mgee:Jointlyownedutilityplantplantcapacity
us-gaap:BalanceSheetLocation
mgee:LeaseLiability

mgee:LeaseRightOfUseAsset

mgee:OperatingLeaseLiabilityCurrentAndNoncurrent
us-gaap:OtherCommitments
mgee:OtherCommitmentInitialAgreedUponCommitmentTotal
us-gaap:RetirementPlanType
mgee:PensionAndOtherPostretirementDefinedBenefitPlansRegulatoryAssetLiability
us-gaap:RetirementPlanType
mgee:PensionAndOtherPostretirementDefinedBenefitPlansRegulatoryAssetLiabilityActuarialNetGainLoss
us-gaap:RetirementPlanType
mgee:PensionAndOtherPostretirementDefinedBenefitPlansRegulatoryAssetLiabilityAmortizationOfPriorServiceCostCredit
us-gaap:RetirementPlanType
mgee:PensionAndOtherPostretirementDefinedBenefitPlansRegulatoryAssetLiabilityAmortizationOfTransitionObligationAssets
us-gaap:JointlyOwnedUtilityPlant
mgee:ProjectedCostsForEnvironmentalRegulation

mgee:PropertyPlantAndEquipmentNetBeforeConstructionInProgress
dei:LegalEntity
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

mgee:PublicUtilitiesInventoryRenewableEnergyCreditAllowance
us-gaap:JointlyOwnedUtilityPlant
mgee:PublicUtilitiesPropertyPlantAndEquipmentPlantInServiceExcludingAFUDC

mgee:PurchaseGasAdjustmentOverUnderCollected
us-gaap:FinancialInstrument
mgee:SecuritiesSoldUnderAgreementsToRepurchaseMaximumExposure
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
mgee:ShortTermDebtCommercialPaperFairValueDisclosure
us-gaap:FairValueByMeasurementBasis

us-gaap:AccumulatedDeferredInvestmentTaxCredit
dei:LegalEntity

us-gaap:AllowanceForDoubtfulAccountsPremiumsAndOtherReceivables
dei:LegalEntity

us-gaap:AllowanceForDoubtfulAccountsReceivable

us-gaap:AllowanceForDoubtfulAccountsReceivableCurrent
dei:LegalEntity

us-gaap:AssetRetirementObligation
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:AssetsFairValueDisclosure
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency

us-gaap:AvailableForSaleSecurities
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:TransactionType
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency, us-gaap:TransactionType
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency, us-gaap:TransactionType
us-gaap:FairValueByMeasurementFrequency, us-gaap:TransactionType

us-gaap:CapitalizationLongtermDebtAndEquity
dei:LegalEntity

us-gaap:CapitalizedComputerSoftwareAccumulatedAmortization

us-gaap:CapitalizedComputerSoftwareNet
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
us-gaap:CashAndCashEquivalentsFairValueDisclosure
us-gaap:FairValueByMeasurementBasis

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsIncludingDisposalGroupAndDiscontinuedOperations
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:Range, us-gaap:PlanName
us-gaap:CommonStockCapitalSharesReservedForFutureIssuance
us-gaap:DebtInstrument
us-gaap:DebtInstrumentCarryingAmount
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:LongtermDebtType
us-gaap:DebtInstrument, us-gaap:LongtermDebtType
us-gaap:DebtInstrumentFaceAmount
us-gaap:DebtInstrument, us-gaap:LongtermDebtType, us-gaap:SubsequentEventType

us-gaap:DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
us-gaap:FairValueByMeasurementBasis

us-gaap:DeferredIncomeTaxLiabilities
dei:LegalEntity

us-gaap:DeferredTaxAssetsDerivativeInstruments
dei:LegalEntity

us-gaap:DeferredTaxAssetsEquityMethodInvestments

us-gaap:DeferredTaxAssetsGross
dei:LegalEntity
dei:LegalEntity
us-gaap:DeferredTaxAssetsOperatingLossCarryforwardsStateAndLocal

us-gaap:DeferredTaxAssetsOther
dei:LegalEntity

us-gaap:DeferredTaxAssetsRegulatoryAssetsAndLiabilities
dei:LegalEntity

us-gaap:DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefits
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesDeferredExpenseDeferredFinancingCosts
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesDerivatives
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesOther
dei:LegalEntity

us-gaap:DeferredTaxLiabilitiesPropertyPlantAndEquipment
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanAccumulatedBenefitObligation

us-gaap:DefinedBenefitPlanAssetsForPlanBenefitsNoncurrent
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsFiveFiscalYearsThereafter
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsNextTwelveMonths
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFive
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearFour
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearThree
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanExpectedFutureBenefitPaymentsYearTwo

us-gaap:DefinedBenefitPlanFairValueOfPlanAssets
mgee:FixedIncomeSecuritiesByInvestmentObjective, us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:EquitySecuritiesByInvestmentObjective, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:FairValueByFairValueHierarchyLevel
us-gaap:RetirementPlanType
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanFundedStatusOfPlan
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlanWithProjectedBenefitObligationInExcessOfPlanAssetsProjectedBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateAccumulatedBenefitObligation
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPensionPlansWithAccumulatedBenefitObligationsInExcessOfPlanAssetsAggregateFairValueOfPlanAssets
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanPlanAssetsTargetAllocationPercentage
us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanByPlanAssetCategories, us-gaap:RetirementPlanType
us-gaap:DefinedBenefitPlanWeightedAverageAssetAllocations
us-gaap:RetirementPlanType

us-gaap:DerivativeAssetCollateralObligationToReturnCashOffset
dei:LegalEntity
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeAssetFairValueGrossLiability
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeAssets
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeAsset
us-gaap:DerivativeInstrumentRisk
us-gaap:BalanceSheetLocation, us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeFairValueOfDerivativeLiability
us-gaap:DerivativeInstrumentRisk
us-gaap:BalanceSheetLocation
us-gaap:DerivativeFairValueOfDerivativeNet
us-gaap:DerivativeInstrumentRisk
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeLiabilities
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency
us-gaap:DerivativeInstrumentRisk
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency

us-gaap:DerivativeLiabilitiesCurrent
dei:LegalEntity

us-gaap:DerivativeLiabilitiesNoncurrent
dei:LegalEntity

us-gaap:DerivativeLiabilityCollateralRightToReclaimCashOffset
us-gaap:DerivativeInstrumentRisk, us-gaap:DerivativeInstrumentsGainLossByHedgingRelationship
us-gaap:DerivativeInstrumentRisk
us-gaap:DerivativeLiabilityFairValueGrossAsset
dei:LegalEntity
us-gaap:DueFromAffiliateCurrent
dei:LegalEntity
us-gaap:DueFromAffiliateNoncurrent
dei:LegalEntity
us-gaap:DueFromAffiliates
us-gaap:RelatedPartyTransactionsByRelatedParty
us-gaap:DueFromRelatedParties
us-gaap:ConsolidatedEntities
us-gaap:DueToAffiliateCurrent
us-gaap:ConsolidatedEntities
us-gaap:DueToAffiliateNoncurrent

us-gaap:EmployeeRelatedLiabilitiesCurrent
dei:LegalEntity

us-gaap:EnergyRelatedInventoryGasStoredUnderground
dei:LegalEntity

us-gaap:EnergyRelatedInventoryOtherFossilFuel
dei:LegalEntity

us-gaap:EquityMethodInvestments
us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs

us-gaap:FinanceLeaseLiability
us-gaap:BalanceSheetLocation
us-gaap:FinanceLeaseLiabilityCurrent

us-gaap:FinanceLeaseLiabilityNoncurrent
dei:LegalEntity

us-gaap:FinanceLeaseLiabilityPaymentsDue

us-gaap:FinanceLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFive

us-gaap:FinanceLeaseLiabilityPaymentsDueYearFour

us-gaap:FinanceLeaseLiabilityPaymentsDueYearThree

us-gaap:FinanceLeaseLiabilityPaymentsDueYearTwo

us-gaap:FinanceLeaseLiabilityUndiscountedExcessAmount
us-gaap:BalanceSheetLocation
us-gaap:FinanceLeaseRightOfUseAsset

us-gaap:FinanceLeaseWeightedAverageDiscountRatePercent

us-gaap:Investments
dei:LegalEntity
us-gaap:ConsolidatedEntities
us-gaap:ConsolidatedEntities
us-gaap:InvestmentsInAndAdvancesToAffiliatesAmountOfEquity
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
us-gaap:JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService
us-gaap:JointlyOwnedUtilityPlant
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
us-gaap:JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
us-gaap:JointlyOwnedUtilityPlant
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
us-gaap:JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation
us-gaap:JointlyOwnedUtilityPlant
dei:LegalEntity, us-gaap:JointlyOwnedUtilityPlant
us-gaap:JointlyOwnedUtilityPlantProportionateOwnershipShare

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths

us-gaap:LettersOfCreditOutstandingAmount
dei:LegalEntity
dei:LegalEntity, us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:LiabilitiesFairValueDisclosure
dei:LegalEntity, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByFairValueHierarchyLevel, us-gaap:FairValueByMeasurementFrequency
us-gaap:FairValueByMeasurementFrequency
dei:LegalEntity, us-gaap:ShortTermDebtType
us-gaap:LineOfCreditFacilityCurrentBorrowingCapacity
us-gaap:ShortTermDebtType
dei:LegalEntity, us-gaap:DebtInstrument, us-gaap:ShortTermDebtType
us-gaap:LineOfCreditFacilityMaximumBorrowingCapacity
us-gaap:ConsolidatedEntities, us-gaap:DebtInstrument, us-gaap:ShortTermDebtType
dei:LegalEntity, us-gaap:FairValueByMeasurementBasis
us-gaap:LongTermDebtFairValue
us-gaap:FairValueByMeasurementBasis

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalAfterYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFive

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree

us-gaap:LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo

us-gaap:MarginDepositAssets
dei:LegalEntity

us-gaap:NotesAndLoansReceivableNetNoncurrent

us-gaap:OperatingLeaseWeightedAverageDiscountRatePercent
dei:LegalEntity, us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwards
us-gaap:IncomeTaxAuthority
dei:LegalEntity, us-gaap:IncomeTaxAuthority
us-gaap:OperatingLossCarryforwardsValuationAllowance
us-gaap:IncomeTaxAuthority
us-gaap:OtherCommitments
us-gaap:OtherCommitment

us-gaap:OtherInventorySupplies
dei:LegalEntity

us-gaap:OtherInvestments
us-gaap:ConsolidatedEntities

us-gaap:OtherReceivablesNetCurrent
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansCurrentLiabilities

us-gaap:PrepaidTaxes
dei:LegalEntity
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsAfterYearFive
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsNextTwelveMonths
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsYearFive1
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsYearFour1
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsYearThree1
us-gaap:RetirementPlanType
us-gaap:PrescriptionDrugSubsidyReceiptsYearTwo1
us-gaap:JointlyOwnedUtilityPlant
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentConstructionWorkInProgress
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentPlantInService
dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus
us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments
us-gaap:JointlyOwnedUtilityPlant
us-gaap:PublicUtilitiesPropertyPlantAndEquipmentPresentValueOfRegulatedAssetForPlantAbandonment

us-gaap:PurchaseObligationDueAfterFifthYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationDueInFifthYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationDueInFourthYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationDueInNextTwelveMonths
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationDueInSecondYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationDueInThirdYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:PurchaseObligationFutureMinimumPaymentsRemainderOfFiscalYear
us-gaap:LongTermPurchaseCommitmentByCategoryOfItemPurchased

us-gaap:RegulatoryAssets
us-gaap:RegulatoryAsset

us-gaap:RegulatoryAssetsCurrent
dei:LegalEntity

us-gaap:RegulatoryAssetsNoncurrent
dei:LegalEntity

us-gaap:RegulatoryLiabilityCurrent
dei:LegalEntity

us-gaap:RegulatoryLiabilityNoncurrent
dei:LegalEntity

us-gaap:RestrictedCashAndCashEquivalentsAtCarryingValue
dei:LegalEntity
us-gaap:FinancialInstrument
us-gaap:SecuritiesSoldUnderAgreementsToRepurchaseGrossIncludingNotSubjectToMasterNettingArrangement
us-gaap:AwardType, us-gaap:PlanName
us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
us-gaap:PlanName

us-gaap:ShortTermBorrowings
dei:LegalEntity

us-gaap:TaxCreditCarryforwardAmount
dei:LegalEntity
dei:LegalEntity, us-gaap:IncomeTaxAuthority
us-gaap:IncomeTaxAuthority

us-gaap:UnbilledReceivablesCurrent
dei:LegalEntity

us-gaap:UnrecognizedTaxBenefitsInterestOnIncomeTaxesAccrued

us-gaap:ValuationAllowancesAndReservesBalance

Plots across concepts


Expenses
Allocated Share Based Compensation Expense
Balance Sheet
Cash And Cash Equivalents At Carrying Value
Assets
Cash And Cash Equivalents At Carrying Value
Current Assets
Other Assets Current
NonCurrent Assets
Other Assets Noncurrent
Liabilities
Liabilities Current
Current Liabilities
Long Term Debt Current
Noncurrent Liabilities
Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent
Stockholders Equity
Common Stock Value
Per Share
Common Stock Dividends Per Share Cash Paid
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 Payments For Other Financing Activities
Shares
Common Stock Shares Issued
LesseeOperatingLeaseLiabilityPaymentsDue
Lessee Operating Lease Liability Payments Due Year Three
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 NANA36.163NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA23.114NANANA23.114NANANA23.114NANANA
 us-gaap:SharesIssued us-gaap:StatementEquityComponents us-gaap:CommonStock█████▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▁▁▁▁▁▁▁▁▁▁▁▁36.16336.16336.16336.16336.16334.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66834.66823.11423.11423.11423.11423.11423.11423.11423.11423.11423.11423.11423.114NANA23.114
us-gaap:CommonStockSharesIssued NANA36.163NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA23.114NANANA23.114NANANA23.114NANANA
us-gaap:CommonStockSharesAuthorized NANA75.0NANANA75.0NANANA75.0NANANA75.0NANANA75.0NANANA75.0NANANA75.0NANANA50.0NANANA50.0NANANA50.0NANANA50.0NANANA
us-gaap:CommonStockSharesOutstanding NANA36.163NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANA34.668NANANANANANANANANANANA
us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding NA36.165NANANA34.668NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:WeightedAverageNumberOfSharesOutstandingBasic NA36.163NANANA34.668NANANANANANANANANANANANANANANANANANANANANANANANANA23.11423.11423.114NA23.11423.11423.114NA23.11423.11423.114NANANA23.114
us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted NANANA36.16335.44134.668NA34.66834.66834.668NA34.66834.66834.668NA34.66834.66834.668NA34.66834.66834.668NA34.66834.66834.668NA34.66834.66834.668NA34.66834.66834.668NANANANANANANANANANANANA
us-gaap:EarningsPerShareBasic ▁█0.630.97NANA0.530.75NANANANANANANANANANANANANANANANANANANANANANANANANA1.050.60.980.461.020.620.690.410.910.550.770.520.860.50.62
us-gaap:EarningsPerShareDiluted NA0.97NANANA0.75NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:EarningsPerShareBasicAndDiluted NANA0.439999999999999950.880.530.750.480.880.450.690.470.850.530.581.040.770.450.560.420.80.470.490.320.820.390.530.440.670.410.80.410.70.40.650.30.680.410.47NANANANANANANANA
  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
 Cost Ratio us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName mgee:ATCequitymethodinvesteemember▁█185.9188.694NA187.833203.071186.801NA184.833182.212177.715NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 EBT margin dei:LegalEntity mgee:Mge▃█▄▄▁▆▄▄▂█▄▄▂▇130.73167.915136.509135.211117.04149.873140.941138.198122.147167.569140.079137.795124.262157.632NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 Net profit Margin dei:LegalEntity mgee:Mge▃█▄▄▁▆▄▄▂█▄▄▂▇▄▄▂▆▄▄▂▅130.73167.915136.509135.211117.04149.873140.941138.198122.147167.569140.079137.795124.262157.632140.274139.539126.462156.836138.938136.728121.589147.543NANANANANANANANANANANANANANANANANANANANANANANANA
 Operating Margin dei:LegalEntity mgee:Mge▃█▄▄▁▆▄▄▂█▄▄▂▇▄▄▂▆▄▄▂▅130.73167.915136.509135.211117.04149.873140.941138.198122.147167.569140.079137.795124.262157.632140.274139.539126.462156.836138.938136.728121.589147.543NANANANANANANANANANANANANANANANANANANANANANANANA
  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 _ _▂▆▁▆▂▄▂▆▂▄▃▆▃▃▃▇▃▅▃█▄▄▂█▃▄▄▆▃▇▃▆▃▆▁▆▃▄▁▆▂▄▂23.39339.05418.71238.32521.5231.4421.87738.73819.78330.51223.9939.79824.23126.18826.27443.00126.55132.9123.95846.52728.21229.53122.17846.17724.04931.85129.56640.1224.44143.97125.96239.924.49737.62819.3539.88825.08128.44417.43936.33423.19730.89820.353NANANA
  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:AllocatedShareBasedCompensationExpense ▅▅█▃▄▁▄▆▅▇0.60.71.60.10.2-0.60.20.90.71.2NANANANANANANANANANANANANANANANANANANANA0.40.1NANA0.00.6NANANANANANANANANANA
 us-gaap:CostOfRevenue us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName mgee:ATCequitymethodinvesteemember▁█92.38495.104NA92.97597.51195.211NA94.71393.57390.387NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic ▃▆▂▇▃▅▂▇▂▅▃▇▃▄▃█▃▅▃█▄▄▂█▃▄▃▆▃█▃▇▃▆▁▇▃▄▁▆▂▄23.73235.39219.16639.09422.53131.0519.77938.11119.05329.71622.00339.10324.17926.36822.74142.21324.27930.46722.07243.59425.43426.97318.64943.70521.48728.86523.78637.61523.12143.98221.90639.04522.55136.26216.69437.89522.86625.9114.65833.53320.29528.434NANANA22.588
us-gaap:IncomeTaxExpenseBenefit ▄▄▅▆▅▅▅▆▅▆▅▆▆▆▁█▆▇▆█▆▇▆█▆▇▆█▆█▆█▆▇▆█▆▆▅▇▆▇▆▇▆▆0.8810.4593.377.33.745.0133.1167.4543.5055.7095.6429.5975.8286.367-13.39315.5848.73611.1677.5715.7149.2849.9457.41715.3518.00810.5878.614.2869.03416.2657.82914.6928.6613.6786.20814.2538.5969.8625.27412.4957.57210.6516.0312.996.4728.328
us-gaap:InterestIncomeExpenseNet ▂▂▂▂▂▁▂▂▂▃▆▆▇▇▇▇▆▆▆▆▆▆▆▆▆▅▅▅▆█▆█▇▇-5.771-5.74-5.781-5.765-5.914-6.061-5.836-5.831-5.749-5.647-5.062-5.025-4.783-4.739-4.817-4.727-4.886-4.894-4.871-5.038-4.957-5.0-5.027-5.036-5.008-5.091-5.123-5.141-4.868-4.541-4.987-4.605-4.657-4.675NANANANANANANANANANANANA
 us-gaap:InterestIncomeExpenseNet dei:LegalEntity mgee:Mge▃▃▃▃▂▁▁▁▁▂▅▅▇▇▇████▇▇▇-5.781-5.753-5.794-5.802-5.935-6.111-6.075-6.095-6.133-5.995-5.47-5.5-5.173-5.054-5.118-4.926-4.998-4.982-4.944-5.109-5.024-5.061NANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NetIncomeLoss ▅█▃▇▃▅▃▇▃▅▃▆▃▄█▆▃▄▂▆▃▃▁▆▂▃▃▅▂▆▂▅▂▄▁▅▂▃▁▄▂▃▂▄▂▂22.85134.93315.79631.79418.79126.03716.66230.65715.54824.00716.36129.50618.35120.00136.13426.62915.54319.314.50227.8816.1517.02811.23228.35413.47918.27815.18623.32914.08727.71714.07724.35313.89122.58410.48623.64214.2716.0489.38421.03812.72317.78311.99719.90911.55214.26
 us-gaap:NetIncomeLossAttributableToNoncontrollingInterest dei:LegalEntity mgee:Mge▁▁▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁5.6275.5015.6395.4935.7685.4935.6245.6145.6215.495.6125.6295.5055.80627.0135.4395.3965.3895.4595.6955.9526.252NANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:NonoperatingIncomeExpense ▇▄▇██▇▅▆▆▆▄▆▆▆▃▅▄▄▄▄▄▄▃▄▄▄▁▄▅▆▂▅▄▅▄▄▄▄▄▄▄▄6.112.0786.2346.5346.9255.6713.7375.2045.0194.8513.0754.334.7314.9191.2843.9392.6142.4512.9852.1052.1792.4421.4982.5642.4462.105-0.6572.6363.5484.5520.9313.752.7113.3092.0942.8562.5492.572.3342.3412.1532.386NANANANA
us-gaap:OperatingIncomeLoss ▂▆▁▆▂▄▂▆▂▄▃▆▃▃▃▇▃▅▃█▄▄▂█▃▄▄▆▃▇▃▆▃▆▁▆▃▄▁▆▂▄▂▅▂▂23.39339.05418.71238.32521.5231.4421.87738.73819.78330.51223.9939.79824.23126.18826.27443.00126.55132.9123.95846.52728.21229.53122.17846.17724.04931.85129.56640.1224.44143.97125.96239.924.49737.62819.3539.88825.08128.44417.43936.33423.19730.89820.35334.35220.12221.775
us-gaap:ProfitLoss ▄█▁▇▂▅▁▆▁▄▁▆22.85134.93315.79631.79418.79126.03716.66230.65715.54824.00716.36129.506NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RegulatedAndUnregulatedOperatingRevenue ▂▅▃▃▂▄▃▃▂▅▃▃▂▄▃▃▂▄▃▃▂▄▃▃▂▅▄▃▂█▄▃▂▅▃▃▂▄▃▃▂▅▃▂▁▄130.73167.915136.509135.211117.04149.873140.941138.198122.147167.569140.079137.795124.262157.632140.274139.539126.463156.823138.925136.717121.576147.527130.973140.795122.126170.134145.707135.135128.765210.245155.263140.099128.288167.237137.005137.838117.221149.259130.946133.572117.259164.605135.928127.938109.082159.643
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService mgee:Totaloperatingrevenue▁█130.73167.915NA135.211117.04149.873NA138.198122.147167.569NA137.795124.262157.632NA139.539126.463156.823NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Commercial,mgee:Electric▄▂▁▆▂▂▂█▄▃▁▇▃▂▂█▅▃52.39147.88345.19957.82247.38847.63447.78463.46652.76249.25345.41961.63850.17447.45247.5464.03654.72150.164NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Commercialandindustrial,mgee:Gas▂▇▅▁▁▆▅▁▂█▆▁▂▇▅▁▂▆9.39725.50716.7215.0526.43821.47118.2184.8257.88328.12520.3325.578.20624.95218.6395.6227.84223.048NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Gastransportation,mgee:Gas▁█1.3322.002NA1.1521.2321.794NA1.1261.0941.536NA0.8291.0531.135NA0.9440.9911.35NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Industrial,mgee:Electric▂▂▁▃▁▁▁▅▃▂▁▅█▂▂██▇3.0883.0012.7173.2342.7632.82.7593.763.3222.9312.6853.6684.632.8952.894.5554.5164.215NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Otherretailandmunicipal,mgee:Electric█▁8.6928.17NA8.628.058.204NA9.5438.9468.239NA9.4318.5278.287NA10.4599.6619.021NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Otherrevenues,mgee:Electric█▁0.410.222NA0.1150.1040.442NA0.2330.2940.451NA0.4820.4540.47NA0.4450.5620.429NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Otherrevenues,mgee:Gas█▁0.0410.003NA0.0030.0040.093NA0.0840.0930.122NA0.0920.1010.127NA0.0910.1080.125NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Residential,mgee:Electric▄▄▂█▃▂▂▇▁▃▁▇▂▂▁▅▁▂36.13736.69433.1245.00934.87433.42832.23442.44230.74934.58130.71942.37132.21733.25931.27639.90531.63433.353NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Residential,mgee:Gas▃█▅▁▂▆▅▁▂█▅▁▂▇▅▁▂▆17.88439.75827.43712.43615.40533.48727.48711.34216.040.31729.9311.91615.6236.55127.53112.12115.1433.903NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Salestothemarket,mgee:Electric▂█▃▃▁▁▃▂▂▃▂▃▅▄▂▂▂▂1.1444.6391.4111.5540.5680.4821.751.1630.791.9611.1041.5052.7952.0340.9771.0681.050.972NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Totalretail,mgee:Electric█▁100.30895.748NA114.68593.07592.066NA119.21195.77995.004NA117.10895.54891.893NA118.955100.53296.753NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService,us-gaap:StatementBusinessSegments mgee:Totalretail,mgee:Gas▁█27.28165.265NA17.48821.84354.958NA16.16723.88368.442NA17.48623.82661.503NA17.74322.98256.951NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:StatementBusinessSegments mgee:Electric▄▄▂▇▃▃▃█▃▄▂█▄▃▃█▄▄▃█▄▃▃█▄▄▁▆▃▄▃█▃▃▂█▃▂▁▇▂▁101.862100.60990.602116.35493.74792.9993.399120.60796.86397.41688.249119.17599.06794.39192.647120.649102.30698.32496.536118.933100.32993.20893.354121.45399.48198.2486.431112.86996.69798.85294.318119.83696.84693.49487.176118.91496.33989.93684.054114.96390.83486.007NANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:StatementBusinessSegments mgee:Gas▂▅▃▁▁▄▃▁▂▅▄▁▂▄▃▁▂▄▃▁▁▄▂▁▁▅▄▁▂█▅▁▂▅▃▁▁▄▃▁▂▆28.65467.2745.69318.64323.07956.84547.32817.37725.0770.151.61518.40724.9862.76547.5418.77824.08158.42642.17517.5720.96153.83735.70917.43120.66969.92858.38521.40431.218110.71372.71818.86430.04272.46747.49216.58718.62957.01945.52317.24925.06277.437NANANANA
 us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:StatementBusinessSegments mgee:NonRegulatedEnergy▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▁▁▁▁▁▁▁0.2140.0360.2140.2140.2140.0380.2140.2140.2140.0530.2150.2130.2150.4760.0870.1120.0760.0730.2140.2140.2860.4821.911.9111.9761.9660.8910.8620.850.6843.9841.3991.41.2762.3372.3372.2532.3041.3691.361.3631.161NANANANA
 us-gaap:Revenues us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName mgee:ATCequitymethodinvesteemember▁█185.9188.694NA187.833203.071186.801NA184.833182.212177.715NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  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 ███▇▇▆▆▆▆▆▅▅▅▄▄▄▄▄▄▄▃▃▃▃▃▃▃▂▂▂▂▃▂▂▂▂▁▁▁2302.0852270.2372253.6512195.7262163.7192072.6972081.6642066.9732026.0862003.5661988.6181974.2971893.4451843.5781855.1821810.01792.5041785.3191801.061760.0721750.5791730.4161730.6731713.8281693.2281684.1911697.6661619.8961596.9631610.4231579.061643.7111590.3091580.441586.9241564.6561506.551482.2971458.882NANA1317.1311317.893NANANA
us-gaap:LiabilitiesAndStockholdersEquity ███▇▇▆▆▆▆▆▅▅▅▄▄▄▄▄▄▄▃▃▃▃▃▃▃▂▂▂▂▃▂▂▂▂▁▁▁2302.0852270.2372253.6512195.7262163.7192072.6972081.6642066.9732026.0862003.5661988.6181974.2971893.4451843.5781855.1821810.01792.5041785.3191801.061760.0721750.5791730.4161730.6731713.8281693.2281684.1911697.6661619.8961596.9631610.4231579.061643.7111590.3091580.441586.9241564.6561506.551482.2971458.882NANA1317.1311317.893NANANA
us-gaap:StockholdersEquity ████▇▆▆▆▅▅▅▅▅▅▅▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁1007.301997.711976.0973.584955.171869.492855.676851.234832.797828.95816.644811.983794.178787.007778.187753.247737.739732.825724.088720.258703.028697.095690.458689.374671.332667.658659.401653.985640.355635.734617.51612.748597.78592.946579.429578.127563.626558.164550.952550.433538.312534.265525.08NANA507.548
  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 ▃▃▄▃▄▁▂▃▄▄▅▇▅▆█▆▆▆▇▆▆▆▆▅▅▅▆▄▄▅▄▄▂▃▄▄▂▂▂191.393201.511209.519199.933217.75162.193181.641204.396211.6221.278240.56280.712242.31248.74290.631255.357249.295254.094275.515249.304254.929247.204254.751241.78230.834235.941253.959225.405218.782238.94220.601213.865186.245195.943222.937219.807178.686179.004189.131NANA155.455162.302NANANA
us-gaap:CashAndCashEquivalentsAtCarryingValue ▂▃▃▄▃▂▂▄▄▅▅█▆▆▇▆▆▇▆▇▇▆▅▆▅▅▄▆▅▆▄▅▃▃▃▄▃▃▃▃▂▂▁34.02540.23944.73853.05851.64217.45123.48161.11269.91382.40283.102133.85595.579101.157107.952104.733102.916117.70295.959111.585110.30897.33181.38494.26775.79170.70365.75588.71987.91193.48968.81375.3342.33345.89446.35759.20341.28840.6641.16944.89332.05430.6857.11NANA10.652
us-gaap:AccountsReceivableNetCurrent ▃▄▃▃▂▃▃▂▂▅▄▃▂▄▄▃▂▃▃▃▁▂▂▂▂▄▃▂▃█▄▂▂▅▃▂▁▃▂37.48343.17241.38439.17733.87939.35240.48235.80535.60647.68243.59341.69335.47343.30742.29938.12935.25239.7539.88740.00731.44436.7137.11235.50734.59943.86141.61435.25137.68562.7644.8937.44235.99446.86441.38633.31530.55138.0936.744NANA43.55740.153NANANA
us-gaap:OtherAssetsCurrent ▂▂▂▂█▂▂▂▂▁▂▂▃▂▃▂▂▂▃▃▃▂▂▂▂▂▂▂▂▂▁▁▁▁▁▂▁▁▁10.4279.04211.3948.81430.0099.24110.2338.6318.9417.5278.5938.45912.71411.17612.50710.04311.329.81912.29313.11513.4029.99210.579.91610.89510.21910.7119.659.6639.3018.2258.3497.8867.4316.6948.8857.0567.0958.27NANA6.3137.769NANANA
  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:AssetsNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName mgee:AtcequitymethodinvesteememberNANA5400.538NANANA5244.22NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:ConstructionInProgressGross ▆▆▆█▇▅▅▄▂▁▆▅▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁▃▆▆▅▅▅▄▃▂▂▂157.477157.97139.099197.594161.542128.321112.48488.0547.57624.649139.671109.20975.00776.06658.04442.27636.51137.58836.7938.2932.18733.19826.35125.01529.20421.32219.02921.33173.71147.449141.415131.096132.75115.80398.41175.74853.43440.85434.055NANA37.557110.435NANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity,us-gaap:PublicUtilityRegulatedOrUnregulatedStatus mgee:Mge,us-gaap:RegulatedOperationNANA721.382NANANA674.251NANANA639.486NANANA599.469NANANA579.965NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity,us-gaap:PublicUtilityRegulatedOrUnregulatedStatus,us-gaap:StatementBusinessSegments mgee:Mge,us-gaap:UnregulatedOperation,mgee:NonRegulatedEnergyNANA74.131NANANA71.623NANANA66.605NANANA61.707NANANA59.223NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PublicUtilityRegulatedOrUnregulatedStatus us-gaap:RegulatedOperationNANA721.382NANANA674.251NANANA639.486NANANA599.469NANANA579.965NANANA578.41NANANA559.615NANANA560.066NANANA546.483NANANANANANANANANANANA
 us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PublicUtilityRegulatedOrUnregulatedStatus,us-gaap:StatementBusinessSegments us-gaap:UnregulatedOperation,mgee:NonRegulatedEnergyNANA74.131NANANA71.623NANANA66.605NANANA61.707NANANA59.37NANANA51.949NANANA45.388NANANA37.851NANANA31.547NANANANANANANANANANANA
us-gaap:PropertyPlantAndEquipmentNet ███▇▇▇▇▆▆▆▅▅▅▄▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▃▃▁▁▁▁▁▁▁▁1827.321791.8781769.3851734.1611686.1591653.1031642.6831612.9751566.7511538.7821509.4371459.4621420.2621366.2141341.3571312.41299.1851287.2361282.0591281.3711266.7741251.481243.4451232.5351223.1691210.4281208.1061197.9231186.4651174.2561160.2241012.281990.554981.325975.053967.556969.707966.069961.511NANA932.09857.572NANANA
 us-gaap:OperatingLeaseRightOfUseAsset us-gaap:BalanceSheetLocation us-gaap:OtherNoncurrentAssetsNANA5.988NANANA0.671NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherAssetsNoncurrent █▇▇▆▅▆▆▅▅▅▄▃▂▁▁▂▂▃▁▂▂▃▂▃▃▂▂▃▂▃▂▃▃▃▂▃▃▃▃27.26822.56422.25918.08717.55518.51819.09317.09615.23216.27212.4888.7295.3792.150.7316.3116.2286.4891.0886.3616.3726.4765.60210.0289.7234.5484.8377.0296.3376.7585.8536.4368.2887.2225.9737.2986.837.0116.524NANA11.1888.641NANANA
  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 ▆▇██▄▄█▄▄▄▅▇▃▃▆▂▂▃▆▆▆▄▄▃▃▃▄▄▅█▅▄▄▄▅▁▁▂▃46.62553.8454.64256.05440.70139.18855.16139.13940.95740.35646.15850.3437.49835.02647.64531.51934.04736.86547.79949.96146.30441.13240.8335.85434.55537.5441.65541.87143.07856.17143.68439.53238.55139.58643.51829.23828.23832.034.532NANA27.88132.555NANANA
us-gaap:LiabilitiesCurrent ▆██▄▄▄▅▆▅▄▄▃▄▃▅▂▂▂▃▂▅▄▂▂▂▂▃▂▂▄▃▂▃▂▂▁▁▁▁145.689183.798190.926115.48109.623111.006128.82152.051128.225112.477120.62898.489118.426106.23126.51484.58283.6483.514103.50586.159128.558117.92384.14674.25876.15171.69189.99682.15686.638109.51596.66678.71290.53184.74675.79759.97662.1262.21163.074NANA51.48981.212NANANA
us-gaap:LongTermDebtCurrent ▁▁▁▅▅▅▅▁▁▁▁▁▁▆▆▁▁▁▁▁██▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁4.8294.84.77119.74219.71419.68619.6594.6324.6054.5794.5534.5274.50224.47724.4524.4284.4044.3814.3334.33334.29434.2644.2664.2454.2244.2034.1824.1624.1414.1214.1024.0823.7213.3653.0132.6672.6672.6672.667NANA2.6671.667NANANA
 us-gaap:OperatingLeaseLiabilityCurrent us-gaap:BalanceSheetLocation us-gaap:OtherCurrentLiabilitiesNANA0.171NANANA0.203NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:OtherLiabilitiesCurrent ▃▂▂▃▄▄▆▄▄▄▆▄▆▄█▅▄▂█▂▄▄▂▂▃▄▆▂▃▃▄▂▅▄▂▁▂▂▃8.9996.7746.0159.04510.27310.21214.67611.12410.3479.25714.11310.50914.4579.56518.75812.26310.0756.24919.4565.9510.0999.1814.915.8218.68210.51113.9315.8248.1398.5189.4896.33712.58610.6055.6373.4216.3246.0478.783NANA9.599.577NANANA
  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 █▇▇█▇▇▇▇▇▇▆▇▆▆▆▇▇▇█▇▆▆▆▆▆▆▆▂▁▁▁▆▅▅▇▇▄▃▂592.664570.517567.422586.279577.469569.585573.427573.529573.847569.856558.003569.427564.743553.208552.32582.765580.687577.511590.676569.861564.193559.607565.055558.113552.599550.638553.013487.451472.624466.791465.47551.811545.536545.27573.207567.054520.645501.673483.953NANA368.513377.25NANANA
 us-gaap:LongTermDebt dei:LegalEntity mgee:MgePowerElmRoadNANA51.59NANANA54.207NANANA56.806NANANA59.416NANANA62.021NANANA64.622NANANANANANANANANANANA73.306NANANA75.972NANANA48.473NANANA
 us-gaap:LongTermDebt dei:LegalEntity mgee:MgePowerWestCampusNANA37.652NANANA39.627NANANA41.496NANANA43.262NANANA44.932NANANA46.51NANANANANANANANANANANA50.0NANANA50.0NANANA50.0NANANA
us-gaap:LongTermDebtNoncurrent █▇▇▇▇▇▇▆▆▆▆▆▃▂▃▂▂▂▂▂▁▁▂▂▂▂▂▂▂▃▃▃▁▁▁▁▁▁▁556.431518.211519.303520.383521.456522.614523.741490.159491.217492.283493.343494.398416.098397.133398.161389.406390.438391.469382.791383.794354.8355.791391.014392.083393.146394.204395.256396.304397.346398.383399.414400.44356.462357.478358.491359.499360.159360.249360.903NANA362.864334.351NANANA
us-gaap:DeferredIncomeTaxLiabilitiesNet ▂▃▁█▇▆▅235.645236.903231.471253.411251.05246.028243.302NANANA231.952NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent ▂▂▃▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▂▃▃▃▃▁▁▁▁▅▅▅▇▇▇▇█77.88177.94178.16868.63268.5568.64768.66564.27465.34766.11667.48369.34669.24969.0369.08865.61666.867.48174.34761.82563.08564.25975.6878.87979.32479.74290.20150.33949.94449.51249.184133.73134.507133.38162.835166.788167.028165.304183.622NANA106.558123.648NANANA
 us-gaap:MinorityInterest dei:LegalEntity mgee:Mge█▇▇▇█▇▇▇▇▇▇▇▇▇▇▁▁▁▁144.824141.697141.196141.057143.064138.796140.303141.179141.065139.444141.454138.842138.713139.208140.902115.389116.45115.554115.665NANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:MinorityInterest dei:LegalEntity mgee:MgePowerElmRoadNANA96.856NANANA97.172NANANA97.519NANANA97.635NANANA80.362NANANA79.113NANANA72.537NANANA69.876NANANA69.803NANANA70.966NANANA99.39NANANA
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us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo NANA0.274NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree NANA0.203NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour NANA0.207NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive NANA0.211NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive NANA8.636NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  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 ████▇▆▆▆▅▅▅▅▅▅▅▄▄▄▄▄▄▃▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▁▁▁▁▁▁1007.301997.711976.0973.584955.171869.492855.676851.234832.797828.95816.644811.983794.178787.007778.187753.247737.739732.825724.088720.258703.028697.095690.458689.374671.332667.658659.401653.985640.355635.734617.51612.748597.78592.946579.429578.127563.626558.164550.952550.433538.312534.265525.08NANA507.548
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity mgee:Mge██▇▇▆▅▅▄▄▃▃▃▂▂▂▁▁▁▁▁▂▂▂918.64900.386871.612862.78840.047795.146777.589737.574714.323704.38689.81676.549654.133643.53632.774608.897600.051600.426602.749620.901640.39643.184641.984NANANA612.26NANANANANANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents mgee:Mge,us-gaap:AdditionalPaidInCapital█████▅▅▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁252.917252.917252.917252.917252.917222.917222.917192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417192.417NANANA192.417NANANANANANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents mgee:Mge,us-gaap:NoncontrollingInterest█▇▇▇█▇▇▇▇▇▇▇▇▇▇▁▁▁▁▁▇▇▇144.824141.697141.196141.057143.064138.796140.303141.179141.065139.444141.454138.842138.713139.208140.902115.389116.45115.554115.665116.206142.67140.593140.308NANANA125.689NANANANANANANANANANANANANANANANANANANA
 us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity,us-gaap:StatementEquityComponents mgee:Mge,us-gaap:RetainedEarnings██▇▆▆▅▅▄▄▃▃▃▂▂▁▁▁▁▁▂▁▂▂503.551488.424460.151451.458426.718416.085397.021386.63363.493355.171338.591327.942305.655294.557282.135283.762273.848275.094277.3294.938287.971292.833291.888NANANA276.662NANANANANANANANANANANANANANANANANANANA
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us-gaap:RetainedEarningsAccumulatedDeficit NANA545.429NANANA504.74NANANA465.708NANANA426.874NANANA372.95NANANA339.165NANANA308.007NANANA266.197NANANA239.953NANANA211.458NANANA185.556NANANA
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 us-gaap:MinorityInterest dei:LegalEntity mgee:Mge█▇▇▇█▇▇▇▇▇▇▇▇▇▇▁▁▁▁144.824141.697141.196141.057143.064138.796140.303141.179141.065139.444141.454138.842138.713139.208140.902115.389116.45115.554115.665NANANANANANANANANANANANANANANANANANANANANANANANANANANA
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 us-gaap:MinorityInterest dei:LegalEntity mgee:MgePowerWestCampusNANA44.34NANANA43.131NANANA43.935NANANA43.267NANANA35.303NANANA37.603NANANA30.755NANANA29.089NANANA30.682NANANA30.676NANANA32.675NANANA
 us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders dei:LegalEntity mgee:Mge▂▅▆█▁▇▇▆▄█▃▆▆█▁▇▄▆▆█▄▇2.55.05.57.51.57.06.55.54.07.53.05.56.07.51.56.54.55.56.07.5614.0526.5NANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders dei:LegalEntity,us-gaap:StatementEquityComponents mgee:Mge,us-gaap:NoncontrollingInterest▂▅▆█▁▇▇▆▄█▃▆▆█▁▇▄▆▆█▄▇2.55.05.57.51.57.06.55.54.07.53.05.56.07.51.56.54.55.56.07.5614.0526.5NANANANANANANANANANANANANANANANANANANANANANANANA
  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
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us-gaap:NetCashProvidedByUsedInInvestingActivities ▄▅▁▂▄▃▅▃▃▅▁▃▁▄▄▆▆▇▇▇▆▇▇▇▇█▆▆▇▇▆▆▅▆▅▆▆█▇▇▇█-42.173-35.835-66.052-55.667-39.894-48.799-37.826-51.897-49.755-32.879-64.894-50.363-63.528-39.543-45.247-24.166-28.82-18.128-22.207-22.646-25.477-16.496-20.132-19.38-21.94-11.861-26.925-24.613-21.445-23.175-27.745-29.632-34.729-29.816-33.165-27.357-25.115-15.716-18.462-16.716-18.692-12.481NANANA-12.268
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us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect ▄▄▄▃█▄▂▄▄▄▁▇▄▄▅▄▃▆-5.908-5.537-7.053-19.854.098-6.02-37.428-8.58-12.594-0.513-50.11234.774-5.978-5.8494.0320.092-14.75821.095NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
 us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect dei:LegalEntity mgee:Mge▅▅▅▃▆▅▄▄▄▅▁█▄▄▅▄▃▆0.2471.5680.199-14.04714.5880.135-1.257-1.506-3.3464.968-41.7840.634-1.424-0.8534.81-5.602-17.23911.682NANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
us-gaap:DeferredIncomeTaxExpenseBenefit ▃▃▃▃▄▃▃▃▄▃▃▃▃▂▁▄▄▂▄▄▄▃▆▃▃▄█▅▆▃▄▅▅▅0.91-0.7961.8993.3763.6551.4332.3482.5583.665-1.3591.3973.0161.129-1.793-8.8923.7734.769-3.7327.385.5196.6822.8414.5571.1692.4783.72325.5089.26615.987-0.8775.65912.2229.1911.294NANANANANANANANANANANANA
us-gaap:NetCashProvidedByUsedInOperatingActivities ▅▆▅▇▄▇▃▃▄▇▂▆▆▆▅▄▄▆▂▅▇▆▂▇▅▅▁▅▄█▄▆▅▄▄█▅▃▃▅▄▅34.6543.88336.43250.56131.63153.81918.77325.81832.68953.19514.60846.81444.6446.97833.97531.30626.45841.25218.32135.67849.78543.72918.5349.66238.35334.647.7936.29226.3158.3731.66742.47237.47628.65230.11855.136.0524.73624.24739.10229.38638.037NANANA30.008
us-gaap:NetIncomeLoss ▅█▃▇▃▅▃▇▃▅▃▆▃▄█▆▃▄▂▆▃▃▁▆▂▃▃▅▂▆▂▅▂▄▁▅▂▃▁▄▂▃▂▄▂▂22.85134.93315.79631.79418.79126.03716.66230.65715.54824.00716.36129.50618.35120.00136.13426.62915.54319.314.50227.8816.1517.02811.23228.35413.47918.27815.18623.32914.08727.71714.07724.35313.89122.58410.48623.64214.2716.0489.38421.03812.72317.78311.99719.90911.55214.26
us-gaap:ProfitLoss ▄█▁▇▂▅▁▆▁▄▁▆22.85134.93315.79631.79418.79126.03716.66230.65715.54824.00716.36129.506NANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANANA
  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 ▄▅▁▂▄▃▅▃▃▅▁▃▁▄▄▆▆▇▇▇▆▇▇▇▇█▆▆▇▇▆▆▅▆▅▆▆█▇▇▇█-42.173-35.835-66.052-55.667-39.894-48.799-37.826-51.897-49.755-32.879-64.894-50.363-63.528-39.543-45.247-24.166-28.82-18.128-22.207-22.646-25.477-16.496-20.132-19.38-21.94-11.861-26.925-24.613-21.445-23.175-27.745-29.632-34.729-29.816-33.165-27.357-25.115-15.716-18.462-16.716-18.692-12.481NANANA-12.268
 us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity mgee:Mge▄▅▁▂▅▄▅▃▄▆▁▃▁▅▄▇▇█▇▇-41.414-35.208-64.694-54.46-38.943-47.164-35.952-49.503-47.202-32.161-63.621-48.87-62.982-37.829-41.553-22.927-26.219-15.959-21.241-22.379NANANANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:PaymentsToAcquirePropertyPlantAndEquipment ▅▄█▇▅▆▄▆▆▄█▆█▅▅▃▃▂▂▃▃▂▂▂▃▁▃▃▂▃▃▃▄▃▄▃▃▂▂▂▂▁40.92134.74664.08453.83838.45946.75835.64749.29747.15931.93363.19648.61262.75837.63141.84524.11726.05216.11721.38621.48225.14915.64219.71919.121.67811.53326.53823.86620.47221.826.95528.95533.97329.16432.52626.35624.08615.46720.31716.26818.7489.843NANANA14.415
  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 ▃▂▅▂█▂▁▄▃▁▃▆▄▂▄▂▂▃▂▂▂▂▂▂▂▁▂▂▂▂▂▄▂▃▂▂▂▂▂▂▂▃1.615-13.58522.567-14.69462.361-11.04-18.37517.4994.472-20.8290.17438.32312.91-13.28414.491-5.323-11.776-2.029-11.74-11.755-11.331-11.286-11.281-11.806-11.325-17.831-3.829-10.871-10.443-10.519-10.43920.157-6.3080.701-9.799-9.828-10.307-9.529-9.509-9.547-9.325-1.981NANANA-11.792
us-gaap:ProceedsFromIssuanceOfLongTermDebt NANA0.00.0NANA50.00.0NANA0.0100.00.00.030.00.00.040.00.00.00.00.0NANANANA0.0NANANA0.085.0NANA0.00.028.00.00.00.00.030.0NANANA50.0
 us-gaap:ProceedsFromIssuanceOfLongTermDebt dei:LegalEntity mgee:MgeNANA0.00.0NANA50.00.0NANA0.0100.00.00.030.00.00.040.00.00.00.00.0NANANANANANANANANANANANANANANANANANANANANANANANA
us-gaap:RepaymentsOfLongTermDebt ▁▁▄▁▄▁▁▁▁▁▁▅▁▁▁▁▁▆▁▁▁▁▁▁▁▁▁▁▁▁▁█▁▁▁▁▆▁▁▁▁▁1.1891.18216.1751.16820.4611.1551.1481.1421.1341.1291.12321.1171.111.1031.0981.0931.08731.081.0751.0691.0641.0591.0541.0481.0431.0371.0341.0271.0231.0191.01240.6670.6660.6670.6680.66628.6670.6670.6660.6670.6670.5NANANA0.277
us-gaap:PaymentsOfDividendsCommonStock ████▇▆▆▆▆▆▆▆▅▅▅▅▄▄▄▄▃▃▃▃▃▃▃▃▂▂▂▂▂▂▂▂▁▁▁▁▁▁13.38113.3813.3813.38112.74712.22112.2212.22111.711.70111.711.70111.1811.18111.1811.18110.66110.6610.6610.66110.22710.22710.22710.2279.7959.7949.7959.7949.429.429.4229.4219.1329.1329.1319.1338.8448.8438.8438.8438.678.67NANANA8.515
  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 End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value363434343434343423232323
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.71.71.91.92.02.02.21.51.61.81.8

Shares Issued

us-gaap:SharesIssued us-gaap:StatementEquityComponents

us-gaap:SharesIssued

us-gaap:CommonStock


Shares
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value3636363636343434343434343434343434343434343434343434343434343423232323232323232323232323232221
Percentage of SharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Issued

us-gaap:CommonStockSharesIssued

us-gaap:CommonStockSharesIssued


Common
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value363434343434343423232323
Percentage of CommonStockSharesIssued100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Authorized

us-gaap:CommonStockSharesAuthorized

us-gaap:CommonStockSharesAuthorized


Common
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value757575757575755050505050
Percentage of CommonStockSharesAuthorized100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Common Stock Shares Outstanding

us-gaap:CommonStockSharesOutstanding

us-gaap:CommonStockSharesOutstanding


Common
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value363434343434343434
Percentage of CommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Diluted Shares Outstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding

us-gaap:WeightedAverageNumberOfDilutedSharesOutstanding


Weighted
Period End2021-03-312020-03-31
Value3634
Percentage of WeightedAverageNumberOfDilutedSharesOutstanding100.0100.0

Weighted Average Number Of Shares Outstanding Basic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic

us-gaap:WeightedAverageNumberOfSharesOutstandingBasic


Weighted
Period End2021-03-312020-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-312010-03-31
Value363423232323232323232323
Percentage of WeightedAverageNumberOfSharesOutstandingBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Weighted Average Number Of Share Outstanding Basic And Diluted

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted

us-gaap:WeightedAverageNumberOfShareOutstandingBasicAndDiluted


Weighted
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-31
Value363534343434343434343434343434343434343434343434
Percentage of WeightedAverageNumberOfShareOutstandingBasicAndDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Basic

us-gaap:EarningsPerShareBasic

us-gaap:EarningsPerShareBasic


Earnings
Period End2021-06-302021-03-312020-06-302020-03-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.630.970.530.751.050.60.980.461.020.620.690.410.910.550.770.520.860.50.62
Percentage of EarningsPerShareBasic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Earnings Per Share Diluted

us-gaap:EarningsPerShareDiluted

us-gaap:EarningsPerShareDiluted


Earnings
Period End2021-03-312020-03-31
Value0.970.75
Percentage of EarningsPerShareDiluted100.0100.0

Earnings Per Share Basic And Diluted

us-gaap:EarningsPerShareBasicAndDiluted

us-gaap:EarningsPerShareBasicAndDiluted


Earnings
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value0.440.880.530.750.480.880.450.690.470.850.530.581.040.770.450.560.420.80.470.490.320.820.390.530.440.670.410.80.410.70.40.650.30.680.410.47
Percentage of EarningsPerShareBasicAndDiluted100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Allocated Share Based Compensation Expense

us-gaap:AllocatedShareBasedCompensationExpense

us-gaap:AllocatedShareBasedCompensationExpense


Allocated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312013-12-312013-09-302012-12-312012-09-30
Value600000.0700000.01600000.0100000.0200000.0-600000.0200000.0900000.0700000.01200000.0400000.0100000.00600000.0
Percentage of AllocatedShareBasedCompensationExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.50.41.20.10.2-0.40.10.70.60.70.30.10.00.4

us-gaap:AllocatedShareBasedCompensationExpense us-gaap:PlanName

mgee:PerformanceUnitPlan2020


Allocated
Period End2020-09-302020-06-30
Value100000.0600000.0
Percentage of AllocatedShareBasedCompensationExpense100.0300.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.10.5
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:PerformanceUnitPlan20200.00.0

Cost Of Revenue

us-gaap:CostOfRevenue us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:CostOfRevenue

mgee:ATCequitymethodinvesteemember


Cost
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value9295929795949390
Percentage of CostOfRevenue100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue70.756.668.883.363.568.576.653.9
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:ATCequitymethodinvesteemember0.00.00.00.00.00.00.00.0

Income Loss From Continuing Operations Before Income Taxes Domestic

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value23351939223119381929223924262242243022432526184321282337234321392236163722251433202822
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue18.221.114.028.919.320.714.027.615.617.715.728.419.516.716.230.319.219.415.931.920.918.314.231.017.617.016.327.818.020.914.127.917.621.712.227.519.517.411.225.117.317.314.1

us-gaap:IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic dei:LegalEntity

mgee:Mge


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value2133173619281835162621372123
Percentage of IncomeLossFromContinuingOperationsBeforeIncomeTaxesDomestic88.794.289.494.286.393.295.393.088.790.899.194.790.390.4
Percentage of RegulatedAndUnregulatedOperatingRevenue16.119.912.627.216.619.313.425.613.816.115.626.917.615.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge16.119.90.027.216.619.30.025.613.816.10.026.917.615.1

Income Tax Expense Benefit

us-gaap:IncomeTaxExpenseBenefit

us-gaap:IncomeTaxExpenseBenefit


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.8810.4593.377.33.745.0133.1167.4543.5055.7095.6429.5975.8286.367-13.393158.736117.57159.2849.9457.417158.008108.6149.034167.829148.66136.208148.5969.8625.274127.572106.03126.4728.328
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 RegulatedAndUnregulatedOperatingRevenue0.70.32.55.43.23.32.25.42.93.44.07.04.74.0-9.511.26.97.15.411.57.66.75.710.96.66.25.910.67.07.75.010.56.88.24.510.37.36.64.09.46.56.54.410.25.95.2

us-gaap:IncomeTaxExpenseBenefit dei:LegalEntity

mgee:Mge


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value0.293-0.4332.8076.6113.0464.3712.8396.6872.9664.9265.5439.1175.2215.581
Percentage of IncomeTaxExpenseBenefit33.3-94.383.390.681.487.291.189.784.686.398.295.089.687.7
Percentage of RegulatedAndUnregulatedOperatingRevenue0.2-0.32.14.92.62.92.04.82.42.94.06.64.23.5
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge0.2-0.30.04.92.62.90.04.82.42.90.06.64.23.5

Interest Income Expense Net

us-gaap:InterestIncomeExpenseNet

us-gaap:InterestIncomeExpenseNet


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-5771000.0-5740000.0-5781000.0-5765000.0-5914000.0-6061000.0-5836000.0-5831000.0-5749000.0-5647000.0-5062000.0-5025000.0-4783000.0-4739000.0-4817000.0-4727000.0-4886000.0-4894000.0-4871000.0-5038000.0-4957000.0-5000000.0-5027000.0-5036000.0-5008000.0-5091000.0-5123000.0-5141000.0-4868000.0-4541000.0-4987000.0-4605000.0-4657000.0-4675000.0
Percentage of InterestIncomeExpenseNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-4.4-3.4-4.2-4.3-5.1-4.0-4.1-4.2-4.7-3.4-3.6-3.6-3.8-3.0-3.4-3.4-3.9-3.1-3.5-3.7-4.1-3.4-3.8-3.6-4.1-3.0-3.5-3.8-3.8-2.2-3.2-3.3-3.6-2.8

us-gaap:InterestIncomeExpenseNet dei:LegalEntity

mgee:Mge


Interest
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-5781000.0-5753000.0-5794000.0-5802000.0-5935000.0-6111000.0-6075000.0-6095000.0-6133000.0-5995000.0-5470000.0-5500000.0-5173000.0-5054000.0-5118000.0-4926000.0-4998000.0-4982000.0-4944000.0-5109000.0-5024000.0-5061000.0
Percentage of InterestIncomeExpenseNet100.2100.2100.2100.6100.4100.8104.1104.5106.7106.2108.1109.5108.2106.6106.2104.2102.3101.8101.5101.4101.4101.2
Percentage of RegulatedAndUnregulatedOperatingRevenue-4.4-3.4-4.2-4.3-5.1-4.1-4.3-4.4-5.0-3.6-3.9-4.0-4.2-3.2-3.6-3.5-4.0-3.2-3.6-3.7-4.1-3.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge-4.4-3.40.0-4.3-5.1-4.10.0-4.4-5.0-3.60.0-4.0-4.2-3.20.0-3.5-4.0-3.20.0-3.7-4.1-3.4

Net Income Loss

us-gaap:NetIncomeLoss

us-gaap:NetIncomeLoss


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value22341531182616301524162918203626151914271617112813181523142714241322102314169.38421121711191114
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 RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.414.812.725.819.112.312.310.420.413.311.58.620.111.010.710.417.310.913.29.117.410.813.57.717.212.210.87.215.810.910.88.815.610.68.9

us-gaap:NetIncomeLoss dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value15288.69324101910238.32216102211128.373198.754128.184211010
Percentage of NetIncomeLoss66.280.955.077.856.673.262.475.553.569.165.175.560.562.223.274.856.366.356.478.862.864.3
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.97.616.28.97.96.014.36.98.25.916.18.37.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge11.616.80.018.39.112.70.016.76.89.90.016.28.97.90.014.36.98.20.016.18.37.4

us-gaap:NetIncomeLoss dei:LegalEntity, us-gaap:ConsolidationItems

mgee:Mge, us-gaap:IntersegmentElimination


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-5.627-5.501-5.639-5.493-5.768-5.493-5.624-5.614-5.621-5.49-5.612-5.629-5.505-5.806-27.013-5.439-5.396-5.389-5.459-5.695-5.952-6.252
Percentage of NetIncomeLoss-24.6-15.7-35.7-17.3-30.7-21.1-33.8-18.3-36.2-22.9-34.3-19.1-30.0-29.0-74.8-20.4-34.7-27.9-37.6-20.4-36.9-36.7
Percentage of RegulatedAndUnregulatedOperatingRevenue-4.3-3.3-4.1-4.1-4.9-3.7-4.0-4.1-4.6-3.3-4.0-4.1-4.4-3.7-19.3-3.9-4.3-3.4-3.9-4.2-4.9-4.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination43.236.10.039.845.740.10.035.346.436.30.039.942.040.90.036.537.435.10.032.633.837.9

mgee:Mge, us-gaap:OperatingSegments


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value15288.69324101910238.32216
Percentage of NetIncomeLoss66.280.955.077.856.673.262.475.553.569.1
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.9
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments11.616.80.018.39.112.70.016.76.89.9

us-gaap:NetIncomeLoss dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:OperatingSegments, mgee:Electric


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value14184.0832410115.413237.8769.3496.78522106.1324.883198.6537.9534.948218.535.992
Percentage of NetIncomeLoss61.851.625.877.954.444.032.577.250.738.941.576.956.330.713.574.755.741.234.175.652.835.2
Percentage of RegulatedAndUnregulatedOperatingRevenue10.810.73.018.38.77.63.817.16.45.64.816.58.33.93.514.36.85.13.615.47.04.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Electric13.917.90.021.210.912.30.019.68.19.60.019.010.56.50.016.58.58.10.017.78.56.4

mgee:Mge, us-gaap:OperatingSegments, mgee:Gas


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.277104.9510.2210.968.0345.44-0.0610.9517.764.410.1761.2896.9914.1450.6840.7845.5322.8340.9721.785.037
Percentage of NetIncomeLoss5.630.231.30.75.130.932.6-0.26.132.327.00.67.035.011.52.65.028.719.53.511.029.6
Percentage of RegulatedAndUnregulatedOperatingRevenue1.06.33.60.20.85.43.9-0.00.84.63.10.11.04.43.00.50.63.52.00.71.53.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Gas4.014.60.01.03.813.30.0-0.33.510.30.00.84.510.40.03.02.98.80.04.16.68.5

mgee:Mge, us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.3555.1945.2985.2515.2255.065.1625.1315.1164.9615.0665.0564.9785.133264.7674.7134.6984.7634.7354.7254.833
Percentage of NetIncomeLoss23.414.933.516.527.819.431.016.732.920.731.017.127.125.772.917.930.324.332.817.029.328.4
Percentage of RegulatedAndUnregulatedOperatingRevenue4.13.13.93.94.53.43.73.74.23.03.63.74.03.318.83.43.73.03.43.53.93.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:NonRegulatedEnergy51.450.90.050.950.750.10.050.150.149.50.049.949.549.90.042.442.142.20.042.242.242.2

us-gaap:NetIncomeLoss us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, mgee:Electric


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value14184.0832410115.413237.8769.3496.78522106.1324.883198.6537.9534.948218.535.9923.16206.276.1115.933187.382103.571197.0867.016
Percentage of NetIncomeLoss61.851.625.877.954.444.032.577.250.738.941.576.956.330.713.574.755.741.234.175.652.835.228.173.546.533.439.177.452.436.125.478.051.031.1
Percentage of RegulatedAndUnregulatedOperatingRevenue10.810.73.018.38.77.63.817.16.45.64.816.58.33.93.514.36.85.13.615.47.04.12.414.85.13.64.113.45.74.82.313.65.54.2
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Electric13.917.90.021.210.912.30.019.68.19.60.019.010.56.50.016.58.58.10.017.78.56.40.017.16.36.20.016.07.610.10.015.87.37.5

us-gaap:OperatingSegments, mgee:Gas


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value1.277104.9510.2210.968.0345.44-0.0610.9517.764.410.1761.2896.9914.1450.6840.7845.5322.8340.9721.785.0372.351.1230.8376.0574.773-0.9050.485115.407-1.2470.3018.976
Percentage of NetIncomeLoss5.630.231.30.75.130.932.6-0.26.132.327.00.67.035.011.52.65.028.719.53.511.029.620.94.06.233.131.4-3.93.441.238.4-5.12.239.7
Percentage of RegulatedAndUnregulatedOperatingRevenue1.06.33.60.20.85.43.9-0.00.84.63.10.11.04.43.00.50.63.52.00.71.53.41.80.80.73.63.3-0.70.45.43.5-0.90.25.4
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Gas4.014.60.01.03.813.30.0-0.33.510.30.00.84.510.40.03.02.98.80.04.16.68.50.05.33.68.30.0-3.91.510.00.0-5.80.911.6

us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value5.3555.1945.2985.2515.2255.065.1625.1315.1164.9615.0665.0564.9785.133264.7674.7134.6984.7634.7354.7254.8335.0245.0165.045.0184.8734.8474.8374.7325.1815.1735.1965.143
Percentage of NetIncomeLoss23.414.933.516.527.819.431.016.732.920.731.017.127.125.772.917.930.324.332.817.029.328.444.717.737.427.532.120.834.317.136.821.237.422.8
Percentage of RegulatedAndUnregulatedOperatingRevenue4.13.13.93.94.53.43.73.74.23.03.63.74.03.318.83.43.73.03.43.53.93.33.83.64.12.93.33.63.82.33.33.74.13.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:NonRegulatedEnergy51.450.90.050.950.750.10.050.150.149.50.049.949.549.90.042.442.142.20.042.242.242.20.042.642.642.50.042.042.041.70.042.943.043.4

us-gaap:OperatingSegments, mgee:TransmissionInvestment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value1.7931.7781.7751.712.2851.6631.9931.7261.6481.5771.9561.1751.3891.7211.5571.3431.51.4811.9881.1981.0551.3350.6911.421.3711.1251.1041.461.4391.4831.431.41.3821.425
Percentage of NetIncomeLoss7.85.111.25.412.26.412.05.610.66.612.04.07.68.64.35.09.77.713.74.36.57.86.25.010.26.27.36.310.25.410.25.79.96.3
Percentage of RegulatedAndUnregulatedOperatingRevenue1.41.11.31.32.01.11.41.21.30.91.40.91.11.11.11.01.20.91.40.90.90.90.51.01.10.70.81.11.10.70.91.01.10.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:TransmissionInvestment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, us-gaap:CorporateAndOther


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0.304-0.619-0.311-0.1490.105-0.183-1.3460.18-0.0430.36-1.8560.4150.3590.024-0.809-0.067-0.107-0.364-0.031-0.1080.06-0.1690.007-0.057-0.039-0.033-1.497-0.14-0.0560.074-1.5120.022-0.0740.024
Percentage of NetIncomeLoss1.3-1.8-2.0-0.50.6-0.7-8.10.6-0.31.5-11.31.42.00.1-2.2-0.3-0.7-1.9-0.2-0.40.4-1.00.1-0.2-0.3-0.2-9.9-0.6-0.40.3-10.70.1-0.50.1
Percentage of RegulatedAndUnregulatedOperatingRevenue0.2-0.4-0.2-0.10.1-0.1-1.00.1-0.00.2-1.30.30.30.0-0.6-0.0-0.1-0.2-0.0-0.10.0-0.10.0-0.0-0.0-0.0-1.0-0.1-0.00.0-1.00.0-0.10.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments us-gaap:CorporateAndOther0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value22341531182616301524162918203626151914271617112813181523142714241322102314169.38421121714
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.414.812.725.819.112.312.310.420.413.311.58.620.111.010.710.417.310.913.29.117.410.813.57.717.212.210.87.215.810.910.88.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Income Loss Attributable To Noncontrolling Interest

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest dei:LegalEntity

us-gaap:NetIncomeLossAttributableToNoncontrollingInterest

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.6275.5015.6395.4935.7685.4935.6245.6145.6215.495.6125.6295.5055.806275.4395.3965.3895.4595.6955.9526.252
Percentage of NetIncomeLossAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.33.34.14.14.93.74.04.14.63.34.04.14.43.719.33.94.33.43.94.24.94.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge4.33.30.04.14.93.70.04.14.63.30.04.14.43.70.03.94.33.40.04.24.94.2

Nonoperating Income Expense

us-gaap:NonoperatingIncomeExpense

us-gaap:NonoperatingIncomeExpense


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value6.112.0786.2346.5346.9255.6713.7375.2045.0194.8513.0754.334.7314.9191.2843.9392.6142.4512.9852.1052.1792.4421.4982.5642.4462.105-0.6572.6363.5484.5520.9313.752.7113.3092.0942.8562.5492.572.3342.3412.1532.386
Percentage of NonoperatingIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.71.24.64.85.93.82.73.84.12.92.23.13.83.10.92.82.11.62.11.51.81.71.11.82.01.2-0.52.02.82.20.62.72.12.01.52.12.21.71.81.81.81.4

us-gaap:NonoperatingIncomeExpense dei:LegalEntity

mgee:Mge


Nonoperating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3.173-0.1044.0144.0933.5313.382.8662.6722.9582.2072.8782.5232.2222.440.2071.1350.1360.1511.5661.0361.11.479
Percentage of NonoperatingIncomeExpense51.9-5.064.462.651.059.676.751.358.945.593.658.347.049.616.128.85.26.252.549.250.560.6
Percentage of RegulatedAndUnregulatedOperatingRevenue2.4-0.12.93.03.02.32.01.92.41.32.11.81.81.50.10.80.10.11.10.80.91.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge2.4-0.10.03.03.02.30.01.92.41.30.01.81.81.50.00.80.10.10.00.80.91.0

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
Value23391838213121381930233924262643263223462829224624312940244325392437193925281736233020342021
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 RegulatedAndUnregulatedOperatingRevenue17.923.313.728.318.421.015.528.016.218.217.128.919.516.618.730.821.021.017.234.023.220.016.932.819.718.720.329.719.020.916.728.519.122.514.128.921.419.113.327.219.818.815.026.918.413.6

us-gaap:OperatingIncomeLoss dei:LegalEntity

mgee:Mge


Operating
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value23391838213122382030183019204029192317312020
Percentage of OperatingIncomeLoss101.1100.4101.1100.6101.5100.7100.9100.3101.5100.978.677.680.779.7153.467.871.669.971.068.270.970.4
Percentage of RegulatedAndUnregulatedOperatingRevenue18.123.313.928.518.721.115.728.116.418.413.522.415.713.228.720.915.014.712.323.216.514.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge18.123.30.028.518.721.10.028.116.418.40.022.415.713.20.020.915.014.70.023.216.514.1

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value223415311826163015241629
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.4

us-gaap:ProfitLoss dei:LegalEntity

mgee:Mge


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value20331430162416281322162716183525141813271617
Percentage of ProfitLoss90.896.790.795.187.394.396.193.889.791.999.494.60.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue15.920.110.522.414.016.411.420.811.413.211.620.313.411.625.218.211.211.69.820.213.211.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge15.920.10.022.414.016.40.020.811.413.20.020.313.411.60.018.211.211.60.020.213.211.7

us-gaap:ProfitLoss dei:LegalEntity, us-gaap:StatementEquityComponents

mgee:Mge, us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.6275.5015.6395.4935.7685.4935.6245.6145.6215.495.6125.6295.5055.806275.4395.3965.3895.4595.6955.9526.252
Percentage of ProfitLoss24.615.735.717.330.721.133.818.336.222.934.319.10.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.33.34.14.14.93.74.04.14.63.34.04.14.43.719.33.94.33.43.94.24.94.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Mge, us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value15288.69324101910238.32216102211128.373198.754128.184211010
Percentage of ProfitLoss66.280.955.077.856.673.262.475.553.569.165.175.50.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.97.616.28.97.96.014.36.98.25.916.18.37.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Regulated And Unregulated Operating Revenue

us-gaap:RegulatedAndUnregulatedOperatingRevenue

us-gaap:RegulatedAndUnregulatedOperatingRevenue


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value130167136135117149140138122167140137124157140139126156138136121147130140122170145135128210155140128167137137117149130133117164135127109159
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue dei:LegalEntity

mgee:Mge


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value130167136135117149140138122167140137124157140139126156138136121147
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue dei:LegalEntity, us-gaap:ConsolidationItems

mgee:Mge, us-gaap:IntersegmentElimination


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-13.028-15.257-13.192-13.805-12.629-13.698-13.716-15.923-12.122-15.134-13.909-14.111-13.095-14.198-14.251-14.912-14.411-15.346-15.553-17.486-17.614-16.514
Percentage of RegulatedAndUnregulatedOperatingRevenue-10.0-9.1-9.7-10.2-10.8-9.1-9.7-11.5-9.9-9.0-9.9-10.2-10.5-9.0-10.2-10.7-11.4-9.8-11.2-12.8-14.5-11.2
Percentage of RegulatedAndUnregulatedOperatingRevenue-10.0-9.1-9.7-10.2-10.8-9.1-9.7-11.5-9.9-9.0-9.9-10.2-10.5-9.0-10.2-10.7-11.4-9.8-11.2-12.8-14.5-11.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value130167136135117149140138122167140137124157140139126156138136121147
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:IntersegmentElimination, mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-0.0460.2730.1810.2090.1850.1910.1840.2250.1980.199-0.055-0.02-0.2450.031-0.176-0.109-0.119-0.1090.4240.4540.560.45
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.00.20.10.20.20.10.10.20.20.1-0.0-0.0-0.20.0-0.1-0.1-0.1-0.10.30.30.50.3
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.00.20.10.20.20.10.10.20.20.1-0.0-0.0-0.20.0-0.1-0.1-0.1-0.10.30.30.50.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:IntersegmentElimination, mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.8774.8112.8573.4942.3553.4513.4995.6791.9294.9624.0174.2193.4934.3473.2663.8913.4234.3854.0936.0346.1355.087
Percentage of RegulatedAndUnregulatedOperatingRevenue2.22.92.12.62.02.32.54.11.63.02.93.12.82.82.32.82.72.82.94.45.03.4
Percentage of RegulatedAndUnregulatedOperatingRevenue2.22.92.12.62.02.32.54.11.63.02.93.12.82.82.32.82.72.82.94.45.03.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:IntersegmentElimination, mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value10101010101010109.9959.9739.9479.9129.8479.821111111111101010
Percentage of RegulatedAndUnregulatedOperatingRevenue7.86.17.47.58.66.77.17.28.26.07.17.27.96.28.08.08.87.17.98.09.07.4
Percentage of RegulatedAndUnregulatedOperatingRevenue7.86.17.47.58.66.77.17.28.26.07.17.27.96.28.08.08.87.17.98.09.07.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments, mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value10110090116939393120979788119989492120102989611910093
Percentage of RegulatedAndUnregulatedOperatingRevenue77.960.166.586.280.362.266.487.479.558.363.086.579.559.965.986.480.862.669.887.383.063.5
Percentage of RegulatedAndUnregulatedOperatingRevenue77.960.166.586.280.362.266.487.479.558.363.086.579.559.965.986.480.862.669.887.383.063.5
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments, mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value31724822256050232675552228675022276246232758
Percentage of RegulatedAndUnregulatedOperatingRevenue24.142.935.616.421.740.236.116.722.144.839.716.422.942.636.216.221.740.133.317.322.339.9
Percentage of RegulatedAndUnregulatedOperatingRevenue24.142.935.616.421.740.236.116.722.144.839.716.422.942.636.216.221.740.133.317.322.339.9
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value10101010101010101010101010101111111111111111
Percentage of RegulatedAndUnregulatedOperatingRevenue8.06.17.67.68.86.77.37.48.46.07.37.38.16.58.08.18.87.18.18.29.27.8
Percentage of RegulatedAndUnregulatedOperatingRevenue8.06.17.67.68.86.77.37.48.46.07.37.38.16.58.08.18.87.18.18.29.27.8
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue dei:LegalEntity, us-gaap:StatementBusinessSegments

mgee:Mge, mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value10110090116939293120969788119999492120102989611810093
Percentage of RegulatedAndUnregulatedOperatingRevenue77.959.966.486.180.162.066.387.379.358.163.086.579.759.966.086.580.962.769.587.082.563.2
Percentage of RegulatedAndUnregulatedOperatingRevenue77.959.966.486.180.162.066.387.379.358.163.086.579.759.966.086.580.962.769.587.082.563.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value28674518235647172570511824624718245842172053
Percentage of RegulatedAndUnregulatedOperatingRevenue21.940.133.513.819.737.933.612.620.541.836.813.420.139.833.913.519.037.330.412.917.236.5
Percentage of RegulatedAndUnregulatedOperatingRevenue21.940.133.513.819.737.933.612.620.541.836.813.420.139.833.913.519.037.330.412.917.236.5
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.2140.0360.2140.2140.2140.0380.2140.2140.2140.0530.2150.2130.2150.4760.0870.1120.0760.0730.2140.2140.2860.482
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.00.20.20.20.00.20.20.20.00.20.20.20.30.10.10.10.00.20.20.20.3
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.00.20.20.20.00.20.20.20.00.20.20.20.30.10.10.10.00.20.20.20.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-13.028-15.257-13.192-13.805-12.629-13.698-13.716-15.923-12.122-15.134-13.909-14.111-13.095-14.198-14.251-14.912-14.41-15.359-15.566-17.497-17.627-16.53-12.891-13.884-12.266-12.687-12.019-12.444-12.692-14.412-12.974-13.589-13.636-15.558
Percentage of RegulatedAndUnregulatedOperatingRevenue-10.0-9.1-9.7-10.2-10.8-9.1-9.7-11.5-9.9-9.0-9.9-10.2-10.5-9.0-10.2-10.7-11.4-9.8-11.2-12.8-14.5-11.2-9.8-9.9-10.0-7.5-8.2-9.2-9.9-6.9-8.4-9.7-10.6-9.3
Percentage of RegulatedAndUnregulatedOperatingRevenue-10.0-9.1-9.7-10.2-10.8-9.1-9.7-11.5-9.9-9.0-9.9-10.2-10.5-9.0-10.2-10.7-11.4-9.8-11.2-12.8-14.5-11.2-9.8-9.9-10.0-7.5-8.2-9.2-9.9-6.9-8.4-9.7-10.6-9.3
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-30
Value130167136135117149140138122167140137124157140139126156138136121147130140122170145135128210155140128
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:IntersegmentElimination, mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-0.0460.2730.1810.2090.1850.1910.1840.2250.1980.199-0.055-0.02-0.2450.031-0.176-0.11-0.119-0.1050.430.4590.5670.4560.1130.1630.1220.1150.1080.1560.1270.1180.1270.1720.1290.109
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.00.20.10.20.20.10.10.20.20.1-0.0-0.0-0.20.0-0.1-0.1-0.1-0.10.30.30.50.30.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue-0.00.20.10.20.20.10.10.20.20.1-0.0-0.0-0.20.0-0.1-0.1-0.1-0.10.30.30.50.30.10.10.10.10.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:IntersegmentElimination mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value2.8774.8112.8573.4942.3553.4513.4995.6791.9294.9624.0174.2193.4934.3473.2663.8923.4224.3944.16.046.1415.0972.9093.8552.2912.7251.2361.6141.8923.6242.182.7572.8164.876
Percentage of RegulatedAndUnregulatedOperatingRevenue2.22.92.12.62.02.32.54.11.63.02.93.12.82.82.32.82.72.83.04.45.13.52.22.71.91.60.81.21.51.71.42.02.22.9
Percentage of RegulatedAndUnregulatedOperatingRevenue2.22.92.12.62.02.32.54.11.63.02.93.12.82.82.32.82.72.83.04.45.13.52.22.71.91.60.81.21.51.71.42.02.22.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:IntersegmentElimination mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IntersegmentElimination, mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value10101010101010109.9959.9739.9479.9129.8479.8211111111111010109.8699.8669.8539.8471010101010101010
Percentage of RegulatedAndUnregulatedOperatingRevenue7.86.17.47.58.66.77.17.28.26.07.17.27.96.28.08.08.87.17.98.09.07.47.57.08.15.87.37.98.35.16.97.68.36.3
Percentage of RegulatedAndUnregulatedOperatingRevenue7.86.17.47.58.66.77.17.28.26.07.17.27.96.28.08.08.87.17.98.09.07.47.57.08.15.87.37.98.35.16.97.68.36.3
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:IntersegmentElimination mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value10110090116939393120979788119989492120102989611910093931219998861139698931209693
Percentage of RegulatedAndUnregulatedOperatingRevenue77.960.166.586.280.362.266.487.479.558.363.086.579.559.965.986.480.862.669.887.383.063.571.486.481.657.859.483.675.247.160.585.775.656.0
Percentage of RegulatedAndUnregulatedOperatingRevenue77.960.166.586.280.362.266.487.479.558.363.086.579.559.965.986.480.862.669.887.383.063.571.486.481.657.859.483.675.247.160.585.775.656.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value317248222560502326755522286750222762462327583821227259233311462213277
Percentage of RegulatedAndUnregulatedOperatingRevenue24.142.935.616.421.740.236.116.722.144.839.716.422.942.636.216.221.740.133.317.322.339.929.515.118.842.740.917.025.754.440.115.425.646.2
Percentage of RegulatedAndUnregulatedOperatingRevenue24.142.935.616.421.740.236.116.722.144.839.716.422.942.636.216.221.740.133.317.322.339.929.515.118.842.740.917.025.754.440.115.425.646.2
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value10101010101010101010101010101111111111111111111111111111111112121211
Percentage of RegulatedAndUnregulatedOperatingRevenue8.06.17.67.68.86.77.37.48.46.07.37.38.16.58.08.18.87.18.18.29.27.89.08.49.76.97.98.58.95.47.88.69.47.1
Percentage of RegulatedAndUnregulatedOperatingRevenue8.06.17.67.68.86.77.37.48.46.07.37.38.16.58.08.18.87.18.18.29.27.89.08.49.76.97.98.58.95.47.88.69.47.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedAndUnregulatedOperatingRevenue us-gaap:StatementBusinessSegments

mgee:Electric


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value10110090116939293120969788119999492120102989611810093931219998861129698941199693871189689841149086
Percentage of RegulatedAndUnregulatedOperatingRevenue77.959.966.486.180.162.066.387.379.358.163.086.579.759.966.086.580.962.769.587.082.563.271.386.381.557.759.383.575.147.060.785.575.555.963.686.382.260.364.286.177.552.3
Percentage of RegulatedAndUnregulatedOperatingRevenue77.959.966.486.180.162.066.387.379.358.163.086.579.759.966.086.580.962.769.587.082.563.271.386.381.557.759.383.575.147.060.785.575.555.963.686.382.260.364.286.177.552.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Gas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value2867451823564717257051182462471824584217205335172069582131110721830724716185745172577
Percentage of RegulatedAndUnregulatedOperatingRevenue21.940.133.513.819.737.933.612.620.541.836.813.420.139.833.913.519.037.330.412.917.236.527.312.416.941.140.115.824.252.746.813.523.443.334.712.015.938.234.812.921.447.0
Percentage of RegulatedAndUnregulatedOperatingRevenue21.940.133.513.819.737.933.612.620.541.836.813.420.139.833.913.519.037.330.412.917.236.527.312.416.941.140.115.824.252.746.813.523.443.334.712.015.938.234.812.921.447.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:NonRegulatedEnergy


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value0.2140.0360.2140.2140.2140.0380.2140.2140.2140.0530.2150.2130.2150.4760.0870.1120.0760.0730.2140.2140.2860.4821.911.9111.9761.9660.8910.8620.850.68431.3991.41.2762.3372.3372.2532.3041.3691.361.3631.161
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.00.20.20.20.00.20.20.20.00.20.20.20.30.10.10.10.00.20.20.20.31.51.41.61.20.60.60.70.328.31.01.10.81.71.71.91.51.01.01.20.7
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.00.20.20.20.00.20.20.20.00.20.20.20.30.10.10.10.00.20.20.20.31.51.41.61.20.60.60.70.328.31.01.10.81.71.71.91.51.01.01.20.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenue From Contract With Customer Including Assessed Tax

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax

mgee:Totaloperatingrevenue


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value130167135117149138122167137124157139126156
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Totaloperatingrevenue0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:ProductOrService, us-gaap:StatementBusinessSegments

mgee:Commercial, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value524745574747476352494561504747645450
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax40.128.50.042.840.531.80.045.943.229.40.044.740.430.10.045.943.332.0
Percentage of RegulatedAndUnregulatedOperatingRevenue40.128.533.142.840.531.833.945.943.229.432.444.740.430.133.945.943.332.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Commercial mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Commercialandindustrial, mgee:Gas


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value9.39725165.0526.43821184.8257.88328205.578.20624185.6227.84223
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax7.215.20.03.75.514.30.03.56.516.80.04.06.615.80.04.06.214.7
Percentage of RegulatedAndUnregulatedOperatingRevenue7.215.212.23.75.514.312.93.56.516.814.54.06.615.813.34.06.214.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Commercialandindustrial mgee:Gas0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Gastransportation, mgee:Gas


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value1.3322.0021.1521.2321.7941.1261.0941.5360.8291.0531.1350.9440.9911.35
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax1.01.20.91.11.20.80.90.90.60.80.70.70.80.9
Percentage of RegulatedAndUnregulatedOperatingRevenue1.01.20.91.11.20.80.90.90.60.80.70.70.80.9
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Gastransportation mgee:Gas0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Industrial, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value3.0883.0012.7173.2342.7632.82.7593.763.3222.9312.6853.6684.632.8952.894.5554.5164.215
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax2.41.80.02.42.41.90.02.72.71.70.02.73.71.80.03.33.62.7
Percentage of RegulatedAndUnregulatedOperatingRevenue2.41.82.02.42.41.92.02.72.71.71.92.73.71.82.13.33.62.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Industrial mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Otherretailandmunicipal, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value8.6928.178.628.058.2049.5438.9468.2399.4318.5278.287109.6619.021
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax6.64.96.46.95.56.97.34.96.86.95.37.57.65.8
Percentage of RegulatedAndUnregulatedOperatingRevenue6.64.96.46.95.56.97.34.96.86.95.37.57.65.8
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Otherretailandmunicipal mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Otherrevenues, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value0.410.2220.1150.1040.4420.2330.2940.4510.4820.4540.470.4450.5620.429
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.30.10.10.10.30.20.20.30.30.40.30.30.40.3
Percentage of RegulatedAndUnregulatedOperatingRevenue0.30.10.10.10.30.20.20.30.30.40.30.30.40.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Otherrevenues mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Otherrevenues, mgee:Gas


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value0.0410.0030.0030.0040.0930.0840.0930.1220.0920.1010.1270.0910.1080.125
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.00.00.00.00.10.10.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue0.00.00.00.00.10.10.10.10.10.10.10.10.10.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Otherrevenues mgee:Gas0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Residential, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value363633453433324230343042323331393133
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax27.621.90.033.329.822.30.030.725.220.60.030.725.921.10.028.625.021.3
Percentage of RegulatedAndUnregulatedOperatingRevenue27.621.924.333.329.822.322.930.725.220.621.930.725.921.122.328.625.021.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Residential mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Residential, mgee:Gas


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value173927121533271116402911153627121533
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax13.723.70.09.213.222.30.08.213.124.10.08.612.623.20.08.712.021.6
Percentage of RegulatedAndUnregulatedOperatingRevenue13.723.720.19.213.222.319.58.213.124.121.48.612.623.219.68.712.021.6
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Residential mgee:Gas0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Salestothemarket, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.1444.6391.4111.5540.5680.4821.751.1630.791.9611.1041.5052.7952.0340.9771.0681.050.972
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.92.80.01.10.50.30.00.80.61.20.01.12.21.30.00.80.80.6
Percentage of RegulatedAndUnregulatedOperatingRevenue0.92.81.01.10.50.31.20.80.61.20.81.12.21.30.70.80.80.6
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Salestothemarket mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Totalretail, mgee:Electric


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value1009511493921199595117959111810096
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax76.757.084.879.561.486.378.456.785.076.958.385.279.561.7
Percentage of RegulatedAndUnregulatedOperatingRevenue76.757.084.879.561.486.378.456.785.076.958.385.279.561.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Totalretail mgee:Electric0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Totalretail, mgee:Gas


Revenue
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-31
Value2765172154162368172361172256
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax20.938.912.918.736.711.719.640.812.719.239.012.718.236.3
Percentage of RegulatedAndUnregulatedOperatingRevenue20.938.912.918.736.711.719.640.812.719.239.012.718.236.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Totalretail mgee:Gas0.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RevenueFromContractWithCustomerIncludingAssessedTax us-gaap:StatementBusinessSegments

mgee:Electric


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value10110090116939293120969788119999492120102989611810093931219998861129698941199693871189689841149086
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax77.959.90.086.180.162.00.087.379.358.10.086.579.759.90.086.580.962.70.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue77.959.966.486.180.162.066.387.379.358.163.086.579.759.966.086.580.962.769.587.082.563.271.386.381.557.759.383.575.147.060.785.575.555.963.686.382.260.364.286.177.552.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Gas


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value2867451823564717257051182462471824584217205335172069582131110721830724716185745172577
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax21.940.10.013.819.737.90.012.620.541.80.013.420.139.80.013.519.037.30.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue21.940.133.513.819.737.933.612.620.541.836.813.420.139.833.913.519.037.330.412.917.236.527.312.416.941.140.115.824.252.746.813.523.443.334.712.015.938.234.812.921.447.0
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:NonRegulatedEnergy


Revenue
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value0.2140.0360.2140.2140.2140.0380.2140.2140.2140.0530.2150.2130.2150.4760.0870.1120.0760.0730.2140.2140.2860.4821.911.9111.9761.9660.8910.8620.850.68431.3991.41.2762.3372.3372.2532.3041.3691.361.3631.161
Percentage of RevenueFromContractWithCustomerIncludingAssessedTax0.20.00.00.20.20.00.00.20.20.00.00.20.20.30.00.10.10.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.00.20.20.20.00.20.20.20.00.20.20.20.30.10.10.10.00.20.20.20.31.51.41.61.20.60.60.70.328.31.01.10.81.71.71.91.51.01.01.20.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Revenues

us-gaap:Revenues us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:Revenues

mgee:ATCequitymethodinvesteemember


Revenuesus-gaap:
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-31
Value185188187203186184182177
Percentage of Revenues100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue142.2112.4138.9173.5124.6133.7149.2106.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:ATCequitymethodinvesteemember0.00.00.00.00.00.00.00.0

Assets

us-gaap:Assets

us-gaap:Assets


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value230222702253219521632072208120662026200319881974189318431855181017921785180117601750173017301713169316841697161915961610157916431590158015861564150614821458131713171281
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets dei:LegalEntity

mgee:Mge


Assetsdei:
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312015-12-31
Value21862143211920572021197019731927188118531834181417281675168416231613161216381669
Percentage of Assets95.094.494.193.793.495.194.893.292.992.592.391.991.390.990.889.790.090.391.096.5
Percentage of Assets95.094.494.193.793.495.194.893.292.992.592.391.991.390.990.889.790.090.391.096.5
Percentage of Assets mgee:Mge100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets dei:LegalEntity, us-gaap:ConsolidationItems

mgee:Mge, us-gaap:IntersegmentElimination


Assetsdei:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-31
Value-0.281-0.755-0.377-0.213-0.99-0.448-1.176-0.883-0.156-0.221-0.187
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.0-0.0-0.0-0.0
Percentage of Assets-0.0-0.0-0.0-0.0-0.0-0.0-0.1-0.0-0.0-0.0-0.0
Percentage of Assets mgee:Mge us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:OperatingSegments, mgee:Electric


Assetsdei:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-31
Value1421130812881250122311931141111210431021974
Percentage of Assets63.162.862.361.761.160.057.858.856.256.756.3
Percentage of Assets63.162.862.361.761.160.057.858.856.256.756.3
Percentage of Assets mgee:Mge us-gaap:OperatingSegments mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments, mgee:Gas


Assetsdei:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-31
Value444408379369368377345333344318298
Percentage of Assets19.719.618.318.218.419.017.517.618.617.717.2
Percentage of Assets19.719.618.318.218.419.017.517.618.617.717.2
Percentage of Assets mgee:Mge us-gaap:OperatingSegments mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:Mge, us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Assetsdei:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-31
Value254257259261262265264266270271277
Percentage of Assets11.312.412.612.913.113.313.414.114.615.116.1
Percentage of Assets11.312.412.612.913.113.313.414.114.615.116.1
Percentage of Assets mgee:Mge us-gaap:OperatingSegments mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidatedEntities

srt:ParentCompany


Assetsus-gaap:
Period End2020-12-312019-12-312018-12-312017-12-31
Value1008890850808
Percentage of Assets44.842.842.743.6
Percentage of Assets44.842.842.743.6
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

us-gaap:Assets us-gaap:ConsolidationItems

us-gaap:IntersegmentElimination


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value-436.614-407.564-377.617-377.797-379.15-378.798-378.635-377.781-376.396-377.8-378.216-390.636-408.566-388.566-413.943-389.8-403.118
Percentage of Assets-19.4-19.6-18.3-18.6-18.9-19.0-19.2-20.0-20.3-21.0-21.9-23.0-25.2-24.3-25.7-24.7-25.4
Percentage of Assets-19.4-19.6-18.3-18.6-18.9-19.0-19.2-20.0-20.3-21.0-21.9-23.0-25.2-24.3-25.7-24.7-25.4
Percentage of Assets us-gaap:IntersegmentElimination100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:OperatingSegments, mgee:Electric


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value1421130812881250122311931141111210431021976948914915905899888
Percentage of Assets63.162.862.361.761.160.057.858.856.256.756.455.956.557.356.256.956.0
Percentage of Assets63.162.862.361.761.160.057.858.856.256.756.455.956.557.356.256.956.0
Percentage of Assets us-gaap:OperatingSegments mgee:Electric100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:Gas


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value444408379369368377345333344318299308263247268265285
Percentage of Assets19.719.618.318.218.419.017.517.618.617.717.318.216.315.516.716.818.0
Percentage of Assets19.719.618.318.218.419.017.517.618.617.717.318.216.315.516.716.818.0
Percentage of Assets us-gaap:OperatingSegments mgee:Gas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value254258259261262265264266270271278281307286312288323
Percentage of Assets11.312.412.612.913.113.313.414.114.615.116.116.619.018.019.418.220.4
Percentage of Assets11.312.412.612.913.113.313.414.114.615.116.116.619.018.019.418.220.4
Percentage of Assets us-gaap:OperatingSegments mgee:NonRegulatedEnergy100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, mgee:TransmissionInvestment


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value7471696866666464617469676766656461
Percentage of Assets3.33.43.43.43.33.33.33.43.34.14.04.04.24.24.14.13.8
Percentage of Assets3.33.43.43.43.33.33.33.43.34.14.04.04.24.24.14.13.8
Percentage of Assets us-gaap:OperatingSegments mgee:TransmissionInvestment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OperatingSegments, us-gaap:CorporateAndOther


Assetsus-gaap:
Period End2020-12-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302017-12-312016-12-312015-12-312014-12-312014-09-302014-06-302014-03-312013-12-312012-12-31
Value495443447453461465472477485465434441443438432431413
Percentage of Assets22.021.321.622.423.023.423.925.226.225.825.126.027.427.426.927.326.0
Percentage of Assets22.021.321.622.423.023.423.925.226.225.825.126.027.427.426.927.326.0
Percentage of Assets us-gaap:OperatingSegments us-gaap:CorporateAndOther100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:Assets us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Assetsus-gaap:
Period End2020-12-312019-12-31
Value54935328
Percentage of Assets243.7256.0
Percentage of Assets243.7256.0
Percentage of Assets mgee:Atcequitymethodinvesteemember100.0100.0

Liabilities And Stockholders Equity

us-gaap:LiabilitiesAndStockholdersEquity

us-gaap:LiabilitiesAndStockholdersEquity


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value230222702253219521632072208120662026200319881974189318431855181017921785180117601750173017301713169316841697161915961610157916431590158015861564150614821458131713171281
Percentage of LiabilitiesAndStockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity dei:LegalEntity

mgee:Mge


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2186214321192057202119701973192718811853183418141728167516841623161316121638
Percentage of LiabilitiesAndStockholdersEquity95.094.494.193.793.495.194.893.292.992.592.391.991.390.990.889.790.090.391.0
Percentage of Assets95.094.494.193.793.495.194.893.292.992.592.391.991.390.990.889.790.090.391.0
Percentage of Assets mgee:Mge100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-312017-12-31
Value1008890850808
Percentage of LiabilitiesAndStockholdersEquity44.842.842.743.6
Percentage of Assets44.842.842.743.6
Percentage of Assets srt:ParentCompany100.0100.0100.0100.0

us-gaap:LiabilitiesAndStockholdersEquity us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Liabilities
Period End2020-12-312019-12-31
Value54935328
Percentage of LiabilitiesAndStockholdersEquity243.7256.0
Percentage of Assets243.7256.0
Percentage of Assets mgee:Atcequitymethodinvesteemember100.0100.0

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value1007997976973955869855851832828816811794787778753737732724720703697690689671667659653640635617612597592579578563558550550538534525507501478427
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets43.843.943.344.344.141.941.141.241.141.441.141.141.942.741.941.641.241.040.240.940.240.339.940.239.639.638.840.440.139.539.137.337.637.536.536.937.437.737.80.00.040.639.80.039.10.00.0

us-gaap:StockholdersEquity dei:LegalEntity

mgee:Mge


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value773758730721696656637596573564548537515504491493483484487
Percentage of StockholdersEquity76.876.074.874.173.075.574.570.168.868.267.166.264.964.163.265.565.666.267.3
Percentage of Assets33.633.432.432.932.231.730.628.928.328.227.627.227.227.426.527.327.027.227.0
Percentage of Assets mgee:Mge35.435.434.535.134.533.332.330.930.530.529.929.629.830.129.230.430.030.129.7

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-312017-12-31
Value976855816778
Percentage of StockholdersEquity100.0100.0100.0100.0
Percentage of Assets43.341.141.141.9
Percentage of Assets srt:ParentCompany96.896.196.196.3

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value394394394394394316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316310280
Percentage of StockholdersEquity39.239.540.440.541.336.437.037.238.038.238.739.039.840.240.642.042.943.243.743.945.045.445.845.947.147.448.048.449.449.751.251.652.953.354.654.756.156.757.457.558.859.260.262.363.064.965.5
Percentage of Assets17.117.417.518.018.215.315.215.315.615.815.916.016.717.217.017.517.617.717.618.018.118.318.318.518.718.818.619.519.819.620.019.219.920.019.920.221.021.321.70.00.024.024.00.024.70.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value3636363636343434343434343434343434343434343434343434343434343423232323232323232323232323232221
Percentage of StockholdersEquity3.63.63.73.73.84.04.14.14.24.24.24.34.44.44.54.64.74.74.84.84.95.05.05.05.25.25.35.35.45.55.63.83.93.94.04.04.14.14.24.24.34.34.44.64.64.85.1
Percentage of Assets1.61.61.61.61.71.71.71.71.71.71.71.81.81.91.91.91.91.91.92.02.02.02.02.02.02.12.02.12.22.22.21.41.51.51.51.51.51.61.60.00.01.81.80.01.80.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value576566545543524518504500481478465461443436426401386381372369351345339338320316308302289284266273258253239238224218211210198194185167162144123
Percentage of StockholdersEquity57.256.855.955.854.959.659.058.857.957.757.056.855.855.454.953.452.452.151.551.250.149.649.149.147.747.446.746.345.144.743.144.643.242.741.441.339.839.238.438.336.936.435.333.132.330.329.0
Percentage of Assets25.025.024.224.724.225.024.224.223.823.923.423.423.423.723.022.221.621.420.721.020.120.019.619.718.918.818.118.718.117.716.916.616.216.015.115.214.914.814.50.00.014.814.10.012.70.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Assets Current

us-gaap:AssetsCurrent

us-gaap:AssetsCurrent


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value191201209199217162181204211221240280242248290255249254275249254247254241230235253225218238220213186195222219178179189155162165
Percentage of AssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets8.38.99.39.110.17.88.79.910.411.012.114.212.813.515.714.113.914.215.314.214.614.314.714.113.614.015.013.913.714.814.013.011.712.414.014.011.912.113.011.812.312.9

us-gaap:AssetsCurrent dei:LegalEntity

mgee:Mge


Assets
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value171168169153165148160148147148162192147151185153153160187
Percentage of AssetsCurrent89.583.580.776.676.091.388.272.469.867.167.568.561.160.863.860.061.463.268.2
Percentage of Assets7.47.47.57.07.67.17.77.27.37.48.29.77.88.210.08.58.59.010.4
Percentage of Assets mgee:Mge7.87.98.07.48.27.58.17.77.88.08.810.68.69.011.09.49.510.011.5

us-gaap:AssetsCurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Assets
Period End2020-12-312019-12-312018-12-312017-12-31
Value382078100
Percentage of AssetsCurrent18.611.232.734.5
Percentage of Assets1.71.04.05.4
Percentage of Assets srt:ParentCompany3.92.39.312.4

us-gaap:AssetsCurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Assets
Period End2020-12-312019-12-31
Value9284
Percentage of AssetsCurrent44.346.6
Percentage of Assets4.14.1
Percentage of Assets mgee:Atcequitymethodinvesteemember1.71.6

Cash And Cash Equivalents At Carrying Value

us-gaap:CashAndCashEquivalentsAtCarryingValue

us-gaap:CashAndCashEquivalentsAtCarryingValue


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value344044535117236169828313395101107104102117951111109781947570658887936875424546594140414432307.11104.7044.1063.789
Percentage of CashAndCashEquivalentsAtCarryingValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.51.82.02.42.40.81.13.03.54.14.26.85.05.55.85.85.76.65.36.36.35.64.75.54.54.23.95.55.55.84.44.62.72.92.93.82.72.72.80.00.02.30.50.00.40.00.0

us-gaap:CashAndCashEquivalentsAtCarryingValue dei:LegalEntity

mgee:Mge


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value6.656.7094.1035.171183.3213.1964.6566.3839.6244.843473.1284.1525.9511.9545.8312310314036264.562
Percentage of CashAndCashEquivalentsAtCarryingValue19.516.79.29.734.919.013.67.69.111.75.835.33.34.15.51.95.719.611.228.337.137.832.96.9
Percentage of Assets0.30.30.20.20.80.20.20.20.30.50.22.40.20.20.30.10.31.30.61.82.32.11.50.3
Percentage of Assets mgee:Mge0.30.30.20.30.90.20.20.20.30.50.32.60.20.20.40.10.41.40.70.00.00.01.60.0

us-gaap:CashAndCashEquivalentsAtCarryingValue us-gaap:ConsolidatedEntities

srt:ParentCompany


Cash
Period End2020-12-312019-12-312018-12-312017-12-31
Value37177598
Percentage of CashAndCashEquivalentsAtCarryingValue83.573.290.391.3
Percentage of Assets1.70.83.85.3
Percentage of Assets srt:ParentCompany3.71.98.812.2

Accounts Receivable Net Current

us-gaap:AccountsReceivableNetCurrent

us-gaap:AccountsReceivableNetCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value374341393339403535474341354342383539394031363735344341353762443735464133303836434035
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.91.81.81.61.91.91.71.82.42.22.11.92.32.32.12.02.22.22.31.82.12.12.12.02.62.52.22.43.92.82.32.33.02.62.12.02.62.53.33.02.8

us-gaap:AccountsReceivableNetCurrent dei:LegalEntity

mgee:Mge


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value37434139333940353547434135434238353939
Percentage of AccountsReceivableNetCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.91.81.81.61.91.91.71.82.42.22.11.92.32.32.12.02.22.2
Percentage of Assets mgee:Mge1.72.02.01.91.72.02.11.91.92.62.42.32.12.62.52.32.22.52.4

Other Assets Current

us-gaap:OtherAssetsCurrent

us-gaap:OtherAssetsCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value109.042118.814309.241108.6318.9417.5278.5938.45912111210119.8191213139.992109.9161010109.659.6639.3018.2258.3497.8867.4316.6948.8857.0567.0958.276.3137.7698.323
Percentage of OtherAssetsCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.50.40.50.41.40.40.50.40.40.40.40.40.70.60.70.60.60.50.70.70.80.60.60.60.60.60.60.60.60.60.50.50.50.50.40.60.50.50.60.50.60.6

us-gaap:OtherAssetsCurrent dei:LegalEntity

mgee:Mge


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value108.94118.7469.9348.767108.5228.9067.4868.5418.42412111210119.80512
Percentage of OtherAssetsCurrent99.398.999.499.233.194.998.498.799.699.599.499.6100.099.999.899.799.999.999.8
Percentage of Assets0.40.40.50.40.50.40.50.40.40.40.40.40.70.60.70.60.60.50.7
Percentage of Assets mgee:Mge0.50.40.50.40.50.40.50.40.50.40.50.50.70.70.70.60.70.60.7

us-gaap:OtherAssetsCurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value1.4943.183.6461.601
Percentage of OtherAssetsCurrent13.131.142.412.8
Percentage of Assets0.10.20.20.1
Percentage of Assets srt:ParentCompany0.10.40.40.2

Assets Noncurrent

us-gaap:AssetsNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

us-gaap:AssetsNoncurrent

mgee:Atcequitymethodinvesteemember


Assets
Period End2020-12-312019-12-31
Value54005244
Percentage of AssetsNoncurrent100.0100.0
Percentage of Assets239.6251.9
Percentage of Assets mgee:Atcequitymethodinvesteemember98.398.4

Construction In Progress Gross

us-gaap:ConstructionInProgressGross

us-gaap:ConstructionInProgressGross


Construction
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value1571571391971611281128847241391097576584236373638323326252921192173147141131132115987553403437110219
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.87.06.29.07.56.25.44.32.31.27.05.54.04.13.12.32.02.12.02.21.81.91.51.51.71.31.11.34.69.29.08.08.37.36.24.83.52.82.32.98.417.2

us-gaap:ConstructionInProgressGross dei:LegalEntity

mgee:Mge


Construction
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value15715713919716112811288472413910975765842363736
Percentage of ConstructionInProgressGross100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.87.06.29.07.56.25.44.32.31.27.05.54.04.13.12.32.02.12.0
Percentage of Assets mgee:Mge7.27.46.69.68.06.55.74.62.51.37.66.04.34.53.42.62.32.32.2

mgee:MgePowerElmRoad


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value0.6970.4680.531.2253.2412.41.9761.1151.440.73272
Percentage of ConstructionInProgressGross0.50.40.42.18.89.110.40.81.52.165.4
Percentage of Assets0.00.00.00.10.20.10.10.10.10.15.5
Percentage of Assets mgee:MgePowerElmRoad0.00.00.00.00.00.00.00.00.00.00.0

mgee:MgePowerWestCampus


Construction
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.6770.3090.4780.61
Percentage of ConstructionInProgressGross0.50.30.31.1
Percentage of Assets0.00.00.00.0
Percentage of Assets mgee:MgePowerWestCampus0.00.00.00.0

us-gaap:ConstructionInProgressGross dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus

mgee:Mge, us-gaap:RegulatedOperation


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1371111385631
Percentage of ConstructionInProgressGross99.099.399.396.885.2
Percentage of Assets6.15.47.03.01.7
Percentage of Assets mgee:Mge us-gaap:RegulatedOperation0.00.00.00.00.0

us-gaap:ConstructionInProgressGross dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:UnregulatedOperation, mgee:NonRegulatedEnergy


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value1.3740.7771.0081.8365.434
Percentage of ConstructionInProgressGross1.00.70.73.214.8
Percentage of Assets0.10.00.10.10.3
Percentage of Assets mgee:Mge us-gaap:UnregulatedOperation mgee:NonRegulatedEnergy0.00.00.00.00.0

us-gaap:ConstructionInProgressGross us-gaap:JointlyOwnedUtilityPlant

mgee:BadgerHollowIIUnits


Construction
Period End2020-12-31
Value5.2
Percentage of ConstructionInProgressGross3.7
Percentage of Assets0.2
Percentage of Assets mgee:BadgerHollowIIUnits0.0

mgee:BadgerHollowIUnits


Construction
Period End2020-12-312019-12-31
Value5418
Percentage of ConstructionInProgressGross39.316.6
Percentage of Assets2.40.9
Percentage of Assets mgee:BadgerHollowIUnits0.00.0

us-gaap:ConstructionInProgressGross us-gaap:PublicUtilityRegulatedOrUnregulatedStatus

us-gaap:RegulatedOperation


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value1371111385631231614096
Percentage of ConstructionInProgressGross99.099.399.396.885.290.589.399.298.4
Percentage of Assets6.15.47.03.01.71.41.08.96.1
Percentage of Assets us-gaap:RegulatedOperation0.00.00.00.00.00.00.00.00.0

us-gaap:ConstructionInProgressGross us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

us-gaap:UnregulatedOperation, mgee:NonRegulatedEnergy


Construction
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value1.3740.7771.0081.8365.4342.5142.0411.1141.548
Percentage of ConstructionInProgressGross1.00.70.73.214.89.510.70.81.6
Percentage of Assets0.10.00.10.10.30.10.10.10.1
Percentage of Assets us-gaap:UnregulatedOperation mgee:NonRegulatedEnergy0.00.00.00.00.00.00.00.00.0

Accumulated Depreciation Depletion And Amortization Property Plant And Equipment

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment

mgee:Mge, us-gaap:RegulatedOperation


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value721674639599579
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.0
Percentage of Assets32.032.432.232.332.2
Percentage of Assets mgee:Mge us-gaap:RegulatedOperation0.00.00.00.00.0

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment dei:LegalEntity, us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:UnregulatedOperation, mgee:NonRegulatedEnergy


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value7471666159
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment10.310.610.410.310.2
Percentage of Assets3.33.43.33.33.3
Percentage of Assets mgee:Mge us-gaap:UnregulatedOperation mgee:NonRegulatedEnergy0.00.00.00.00.0

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PublicUtilityRegulatedOrUnregulatedStatus

us-gaap:RegulatedOperation


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value721674639599579578559560546
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment100.0100.0100.0100.0100.00.00.00.00.0
Percentage of Assets32.032.432.232.332.233.433.035.534.4
Percentage of Assets us-gaap:RegulatedOperation0.00.00.00.00.00.00.00.00.0

us-gaap:AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment us-gaap:PublicUtilityRegulatedOrUnregulatedStatus, us-gaap:StatementBusinessSegments

us-gaap:UnregulatedOperation, mgee:NonRegulatedEnergy


Accumulated
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-31
Value747166615951453731
Percentage of AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment10.310.610.410.310.20.00.00.00.0
Percentage of Assets3.33.43.33.33.33.02.72.42.0
Percentage of Assets us-gaap:UnregulatedOperation mgee:NonRegulatedEnergy0.00.00.00.00.00.00.00.00.0

Property Plant And Equipment Net

us-gaap:PropertyPlantAndEquipmentNet

us-gaap:PropertyPlantAndEquipmentNet


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value18271791176917341686165316421612156615381509145914201366134113121299128712821281126612511243123212231210120811971186117411601012990981975967969966961932857719
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets79.478.978.579.077.979.878.978.077.376.875.973.975.074.172.372.572.572.171.272.872.472.371.871.972.271.971.274.074.372.973.561.662.362.161.461.864.465.265.970.865.156.2

us-gaap:PropertyPlantAndEquipmentNet dei:LegalEntity

mgee:Mge


Property
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value1827179117691734168616531642161315661538150914591420136613411312129912871281
Percentage of PropertyPlantAndEquipmentNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets79.478.978.579.077.979.878.978.077.376.875.973.975.074.172.372.572.572.171.1
Percentage of Assets mgee:Mge83.683.683.584.383.483.983.283.783.383.082.380.482.181.579.780.880.579.878.2

Operating Lease Right Of Use Asset

us-gaap:OperatingLeaseRightOfUseAsset us-gaap:BalanceSheetLocation

us-gaap:OperatingLeaseRightOfUseAsset

us-gaap:OtherNoncurrentAssets


Operating
Period End2020-12-312019-12-31
Value5988000.0671000.0
Percentage of OperatingLeaseRightOfUseAsset100.0100.0
Percentage of Assets0.30.0
Percentage of Assets us-gaap:OtherNoncurrentAssets0.00.0

Other Assets Noncurrent

us-gaap:OtherAssetsNoncurrent

us-gaap:OtherAssetsNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value27222218171819171516128.7295.3792.150.7316.3116.2286.4891.0886.3616.3726.4765.602109.7234.5484.8377.0296.3376.7585.8536.4368.2887.2225.9737.2986.837.0116.524118.6417.282
Percentage of OtherAssetsNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.21.01.00.80.80.90.90.80.80.80.60.40.30.10.00.30.30.40.10.40.40.40.30.60.60.30.30.40.40.40.40.40.50.50.40.50.50.50.40.80.70.6

us-gaap:OtherAssetsNoncurrent dei:LegalEntity

mgee:Mge


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value2722221818191918161714107.5584.5123.284.0663.9974.24.353
Percentage of OtherAssetsNoncurrent101.0101.4100.8102.3102.8102.9103.1106.3107.1108.9113.2120.5140.5209.9448.764.464.264.7400.1
Percentage of Assets1.21.01.00.80.80.90.90.90.80.90.70.50.40.20.20.20.20.20.2
Percentage of Assets mgee:Mge1.31.11.10.90.91.01.00.90.91.00.80.60.40.30.20.30.20.30.3

us-gaap:OtherAssetsNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.3640.4980.110.171
Percentage of OtherAssetsNoncurrent1.62.60.923.4
Percentage of Assets0.00.00.00.0
Percentage of Assets srt:ParentCompany0.00.10.00.0

Accounts Payable Current

us-gaap:AccountsPayableCurrent

us-gaap:AccountsPayableCurrent


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value465354564039553940404650373547313436474946414035343741414356433938394329283234273235
Percentage of AccountsPayableCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.02.42.42.61.91.92.61.92.02.02.32.52.01.92.61.71.92.12.72.82.62.42.42.12.02.22.52.62.73.52.82.42.42.52.71.91.92.22.42.12.52.8

us-gaap:AccountsPayableCurrent dei:LegalEntity

mgee:Mge


Accounts
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value46535456403854394040465037354731343647
Percentage of AccountsPayableCurrent100.099.999.9100.099.799.399.499.999.9100.0100.0100.0100.0100.099.9100.0100.0100.0100.0
Percentage of Assets2.02.42.42.61.91.92.61.92.02.02.32.52.01.92.61.71.92.12.7
Percentage of Assets mgee:Mge2.12.52.62.72.02.02.82.02.22.22.52.82.22.12.81.92.12.32.9

Liabilities Current

us-gaap:LiabilitiesCurrent

us-gaap:LiabilitiesCurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value1451831901151091111281521281121209811810612684838310386128117847476718982861099678908475596262635181127
Percentage of LiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.38.18.55.35.15.46.27.46.35.66.15.06.35.86.84.74.74.75.74.97.36.84.94.34.54.35.35.15.46.86.14.85.75.44.83.84.14.24.33.96.29.9

us-gaap:LiabilitiesCurrent dei:LegalEntity

mgee:Mge


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value149185192118112113128154130115121100119106124858383103
Percentage of LiabilitiesCurrent102.4101.1101.0102.4102.7102.099.4101.5101.9102.5100.4101.9101.099.998.4100.9100.4100.199.8
Percentage of Assets6.58.28.65.45.25.56.17.56.55.86.15.16.35.86.74.74.74.75.7
Percentage of Assets mgee:Mge6.88.79.15.75.65.76.58.06.96.26.65.56.96.37.45.35.25.26.3

us-gaap:LiabilitiesCurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.5962.8443.1172.712
Percentage of LiabilitiesCurrent0.32.22.62.1
Percentage of Assets0.00.10.20.1
Percentage of Assets srt:ParentCompany0.10.30.40.3

us-gaap:LiabilitiesCurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Liabilities
Period End2020-12-312019-12-31
Value310502
Percentage of LiabilitiesCurrent162.8390.2
Percentage of Assets13.824.1
Percentage of Assets mgee:Atcequitymethodinvesteemember5.79.4

Long Term Debt Current

us-gaap:LongTermDebtCurrent

us-gaap:LongTermDebtCurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value4.8294.84.771191919194.6324.6054.5794.5534.5274.50224244.4284.4044.3814.3334.33334344.2664.2454.2244.2034.1824.1624.1414.1214.1024.0823.7213.3653.0132.6672.6672.6672.6672.6671.6671.528
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.90.90.90.90.20.20.20.20.20.21.31.30.20.20.20.20.22.02.00.20.20.20.20.20.30.30.30.30.20.20.20.20.20.20.20.20.20.10.1

us-gaap:LongTermDebtCurrent dei:LegalEntity

mgee:Mge


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value4.8294.84.771191919194.6324.6054.5794.5534.5274.50224244.4284.4044.3814.333
Percentage of LongTermDebtCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.20.20.20.90.90.90.90.20.20.20.20.20.21.31.30.20.20.20.2
Percentage of Assets mgee:Mge0.20.20.21.01.01.01.00.20.20.20.20.20.31.51.50.30.30.30.3

Operating Lease Liability Current

us-gaap:OperatingLeaseLiabilityCurrent us-gaap:BalanceSheetLocation

us-gaap:OperatingLeaseLiabilityCurrent

us-gaap:OtherCurrentLiabilities


Operating
Period End2020-12-312019-12-31
Value171000.0203000.0
Percentage of OperatingLeaseLiabilityCurrent100.0100.0
Percentage of Assets0.00.0
Percentage of Assets us-gaap:OtherCurrentLiabilities0.00.0

Other Liabilities Current

us-gaap:OtherLiabilitiesCurrent

us-gaap:OtherLiabilitiesCurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value8.9996.7746.0159.04510101411109.2571410149.5651812106.249195.95109.1814.915.8218.68210135.8248.1398.5189.4896.33712105.6373.4216.3246.0478.7839.599.57713
Percentage of OtherLiabilitiesCurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.40.30.30.40.50.50.70.50.50.50.70.50.80.51.00.70.60.41.10.30.60.50.30.30.50.60.80.40.50.50.60.40.80.70.40.20.40.40.60.70.71.0

us-gaap:OtherLiabilitiesCurrent dei:LegalEntity

mgee:Mge


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value116.7766.0429.04810101211109.0541110149.55716129.7026.02819
Percentage of OtherLiabilitiesCurrent132.1100.0100.4100.0100.0100.086.4100.0100.097.882.3100.099.999.989.398.596.396.599.4
Percentage of Assets0.50.30.30.40.50.50.60.50.50.50.60.50.80.50.90.70.50.31.1
Percentage of Assets mgee:Mge0.50.30.30.40.50.50.60.60.50.50.60.60.80.61.00.70.60.41.2

us-gaap:OtherLiabilitiesCurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-312017-12-31
Value0.0662.3142.52.047
Percentage of OtherLiabilitiesCurrent1.115.817.710.9
Percentage of Assets0.00.10.10.1
Percentage of Assets srt:ParentCompany0.00.30.30.3

Liabilities Noncurrent

us-gaap:LiabilitiesNoncurrent

us-gaap:LiabilitiesNoncurrent


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value592570567586577569573573573569558569564553552582580577590569564559565558552550553487472466465551545545573567520501483368377332
Percentage of LiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets25.725.125.226.726.727.527.527.728.328.428.128.829.830.029.832.232.432.332.832.432.232.332.632.632.632.732.630.129.629.029.533.634.334.536.136.234.633.833.228.028.625.9

us-gaap:LiabilitiesNoncurrent dei:LegalEntity

mgee:Mge


Liabilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value561538536555547539544544545541530542539528528539539536549
Percentage of LiabilitiesNoncurrent94.894.494.594.894.794.894.995.095.095.195.195.495.595.695.792.692.992.993.1
Percentage of Assets24.423.723.825.325.326.026.126.426.927.026.727.528.528.728.529.830.130.130.5
Percentage of Assets mgee:Mge25.725.125.327.027.127.427.628.329.029.228.929.931.231.631.433.333.433.333.6

us-gaap:LiabilitiesNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Liabilities
Period End2020-12-312019-12-312018-12-312017-12-31
Value32313027
Percentage of LiabilitiesNoncurrent5.75.55.44.9
Percentage of Assets1.41.51.51.5
Percentage of Assets srt:ParentCompany3.23.63.63.4

us-gaap:LiabilitiesNoncurrent us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Liabilities
Period End2020-12-312019-12-31
Value378298
Percentage of LiabilitiesNoncurrent66.752.1
Percentage of Assets16.814.4
Percentage of Assets mgee:Atcequitymethodinvesteemember6.95.6

Long Term Debt

us-gaap:LongTermDebt dei:LegalEntity

us-gaap:LongTermDebt

mgee:MgePowerElmRoad


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312012-12-312011-12-312010-12-31
Value515456596264737548
Percentage of LongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets2.32.62.93.23.43.74.65.23.7
Percentage of Assets mgee:MgePowerElmRoad0.00.00.00.00.00.00.00.00.0

mgee:MgePowerWestCampus


Long
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312012-12-312011-12-312010-12-31
Value373941434446505050
Percentage of LongTermDebt73.073.173.072.872.472.068.265.8103.2
Percentage of Assets1.71.92.12.32.52.73.23.43.8
Percentage of Assets mgee:MgePowerWestCampus0.00.00.00.00.00.00.00.00.0

Long Term Debt Noncurrent

us-gaap:LongTermDebtNoncurrent

us-gaap:LongTermDebtNoncurrent


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value556518519520521522523490491492493494416397398389390391382383354355391392393394395396397398399400356357358359360360360362334320
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets24.222.823.023.724.125.225.223.724.224.624.825.022.021.521.521.521.821.921.321.820.320.622.622.923.223.423.324.524.924.725.324.422.422.622.623.023.924.324.727.525.425.0

us-gaap:LongTermDebtNoncurrent dei:LegalEntity

mgee:Mge


Long
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value556518519520521522523490491492493494416397398389390391382
Percentage of LongTermDebtNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets24.222.823.023.724.125.225.223.724.224.624.825.022.021.521.521.521.821.921.3
Percentage of Assets mgee:Mge25.524.224.525.325.826.526.525.426.126.626.927.324.123.723.624.024.224.323.4

Deferred Income Tax Liabilities Net

us-gaap:DeferredIncomeTaxLiabilitiesNet

us-gaap:DeferredIncomeTaxLiabilitiesNet


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value235236231253251246243231
Percentage of DeferredIncomeTaxLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets10.210.410.311.511.611.911.711.7

us-gaap:DeferredIncomeTaxLiabilitiesNet dei:LegalEntity

mgee:Mge


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312018-12-31
Value204204200223220216214204
Percentage of DeferredIncomeTaxLiabilitiesNet86.886.586.688.087.987.988.088.2
Percentage of Assets8.99.08.910.210.210.410.310.3
Percentage of Assets mgee:Mge9.49.69.510.810.911.010.811.2

us-gaap:DeferredIncomeTaxLiabilitiesNet us-gaap:ConsolidatedEntities

srt:ParentCompany


Deferred
Period End2020-12-312019-12-312018-12-31
Value292927
Percentage of DeferredIncomeTaxLiabilitiesNet12.911.911.7
Percentage of Assets1.31.41.4
Percentage of Assets srt:ParentCompany3.03.33.2

Pension And Other Postretirement Defined Benefit Plans Liabilities Noncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value77777868686868646566676969696965666774616364757879799050494949133134133162166167165183106123122
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.43.43.53.13.23.33.33.13.23.33.43.53.73.73.73.63.73.84.13.53.63.74.44.64.74.75.33.13.13.13.18.18.58.410.310.711.111.212.68.19.49.6

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent dei:LegalEntity

mgee:Mge


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value77777868686868646566676969696965666774
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.43.43.53.13.23.33.33.13.23.33.43.53.73.73.73.63.73.84.1
Percentage of Assets mgee:Mge3.63.63.73.33.43.53.53.33.53.63.73.84.04.14.14.04.14.24.5

us-gaap:PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent us-gaap:RetirementPlanType

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value3432323335
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent44.346.648.449.048.0
Percentage of Assets1.51.51.61.82.0
Percentage of Assets us-gaap:OtherPostretirementBenefitPlansDefinedBenefit0.00.00.00.00.0

us-gaap:PensionPlansDefinedBenefit


Pension
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value4336343538
Percentage of PensionAndOtherPostretirementDefinedBenefitPlansLiabilitiesNoncurrent55.553.251.551.052.0
Percentage of Assets1.91.81.71.92.1
Percentage of Assets us-gaap:PensionPlansDefinedBenefit0.00.00.00.00.0

Minority Interest

us-gaap:MinorityInterest dei:LegalEntity

us-gaap:MinorityInterest

mgee:Mge


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value144141141141143138140141141139141138138139140115116115115
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.36.26.36.46.66.76.76.87.07.07.17.07.37.67.66.46.56.56.4
Percentage of Assets mgee:Mge6.66.66.76.97.17.07.17.37.57.57.77.78.08.38.47.17.27.27.1

mgee:MgePowerElmRoad


Minority
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value9697979780797269697099
Percentage of MinorityInterest68.669.368.969.369.50.00.00.00.00.00.0
Percentage of Assets4.34.74.95.34.54.64.34.44.44.97.5
Percentage of Assets mgee:MgePowerElmRoad0.00.00.00.00.00.00.00.00.00.00.0

mgee:MgePowerWestCampus


Minority
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value4443434335373029303032
Percentage of MinorityInterest31.430.731.130.730.50.00.00.00.00.00.0
Percentage of Assets2.02.12.22.32.02.21.81.81.92.12.5
Percentage of Assets mgee:MgePowerWestCampus0.00.00.00.00.00.00.00.00.00.00.0

Other Liabilities Noncurrent

us-gaap:OtherLiabilitiesNoncurrent

us-gaap:OtherLiabilitiesNoncurrent


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value857172656360637069676872726869636665666663626160585750525154525253535048464478676048
Percentage of OtherLiabilitiesNoncurrent100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.73.13.23.02.92.93.03.43.43.43.43.73.83.73.73.53.73.63.73.83.63.63.63.53.53.43.03.33.33.43.33.23.33.43.23.13.13.05.45.14.63.8

us-gaap:OtherLiabilitiesNoncurrent dei:LegalEntity

mgee:Mge


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value85717265626062706967687272686963666566
Percentage of OtherLiabilitiesNoncurrent100.3100.299.9100.0100.0100.099.999.9100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets3.73.13.23.02.92.93.03.43.43.43.43.73.83.73.73.53.73.63.7
Percentage of Assets mgee:Mge3.93.33.43.23.13.13.23.73.73.73.74.04.24.14.13.94.14.04.1

us-gaap:OtherLiabilitiesNoncurrent us-gaap:ConsolidatedEntities

srt:ParentCompany


Other
Period End2020-12-312019-12-312018-12-31
Value0.0370.0410.0
Percentage of OtherLiabilitiesNoncurrent0.10.10.0
Percentage of Assets0.00.00.0
Percentage of Assets srt:ParentCompany0.00.00.0

Operating Lease Liability Noncurrent

us-gaap:OperatingLeaseLiabilityNoncurrent us-gaap:BalanceSheetLocation

us-gaap:OperatingLeaseLiabilityNoncurrent

us-gaap:OtherNoncurrentLiabilities


Operating
Period End2020-12-312019-12-31
Value5840000.0496000.0
Percentage of OperatingLeaseLiabilityNoncurrent100.0100.0
Percentage of Assets0.30.0
Percentage of Assets us-gaap:OtherNoncurrentLiabilities0.00.0

Lessee Operating Lease Liability Payments Due Year Two

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearTwo


Lessee
Period End2020-12-31
Value274000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearTwo100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Three

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearThree


Lessee
Period End2020-12-31
Value203000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearThree100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Four

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFour


Lessee
Period End2020-12-31
Value207000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFour100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueYearFive


Lessee
Period End2020-12-31
Value211000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueYearFive100.0
Percentage of Assets0.0

Lessee Operating Lease Liability Payments Due After Year Five

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive


Lessee
Period End2020-12-31
Value8636000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive100.0
Percentage of Assets0.4

Lessee Operating Lease Liability Payments Due

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue

us-gaap:LesseeOperatingLeaseLiabilityPaymentsDue


Lessee
Period End2020-12-31
Value9869000.0
Percentage of LesseeOperatingLeaseLiabilityPaymentsDue100.0
Percentage of Assets0.4

Lessee Operating Lease Liability Undiscounted Excess Amount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount

us-gaap:LesseeOperatingLeaseLiabilityUndiscountedExcessAmount


Lessee
Period End2020-12-31
Value3858000.0
Percentage of LesseeOperatingLeaseLiabilityUndiscountedExcessAmount100.0
Percentage of Assets0.2

Stockholders Equity

us-gaap:StockholdersEquity

us-gaap:StockholdersEquity


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value1007997976973955869855851832828816811794787778753737732724720703697690689671667659653640635617612597592579578563558550550538534525507501478427
Percentage of StockholdersEquity100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets43.843.943.344.344.141.941.141.241.141.441.141.141.942.741.941.641.241.040.240.940.240.339.940.239.639.638.840.440.139.539.137.337.637.536.536.937.437.737.80.00.040.639.80.039.10.00.0

us-gaap:StockholdersEquity dei:LegalEntity

mgee:Mge


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value773758730721696656637596573564548537515504491493483484487
Percentage of StockholdersEquity76.876.074.874.173.075.574.570.168.868.267.166.264.964.163.265.565.666.267.3
Percentage of Assets33.633.432.432.932.231.730.628.928.328.227.627.227.227.426.527.327.027.227.0
Percentage of Assets mgee:Mge35.435.434.535.134.533.332.330.930.530.529.929.629.830.129.230.430.030.129.7

us-gaap:StockholdersEquity us-gaap:ConsolidatedEntities

srt:ParentCompany


Stockholders
Period End2020-12-312019-12-312018-12-312017-12-31
Value976855816778
Percentage of StockholdersEquity100.0100.0100.0100.0
Percentage of Assets43.341.141.141.9
Percentage of Assets srt:ParentCompany96.896.196.196.3

us-gaap:StockholdersEquity us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value394394394394394316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316316310280
Percentage of StockholdersEquity39.239.540.440.541.336.437.037.238.038.238.739.039.840.240.642.042.943.243.743.945.045.445.845.947.147.448.048.449.449.751.251.652.953.354.654.756.156.757.457.558.859.260.262.363.064.965.5
Percentage of Assets17.117.417.518.018.215.315.215.315.615.815.916.016.717.217.017.517.617.717.618.018.118.318.318.518.718.818.619.519.819.620.019.219.920.019.920.221.021.321.70.00.024.024.00.024.70.00.0
Percentage of Assets us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:CommonStock


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value3636363636343434343434343434343434343434343434343434343434343423232323232323232323232323232221
Percentage of StockholdersEquity3.63.63.73.73.84.04.14.14.24.24.24.34.44.44.54.64.74.74.84.84.95.05.05.05.25.25.35.35.45.55.63.83.93.94.04.04.14.14.24.24.34.34.44.64.64.85.1
Percentage of Assets1.61.61.61.61.71.71.71.71.71.71.71.81.81.91.91.91.91.91.92.02.02.02.02.02.02.12.02.12.22.22.21.41.51.51.51.51.51.61.60.00.01.81.80.01.80.00.0
Percentage of Assets us-gaap:CommonStock0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-03-312009-12-312008-12-312007-12-31
Value576566545543524518504500481478465461443436426401386381372369351345339338320316308302289284266273258253239238224218211210198194185167162144123
Percentage of StockholdersEquity57.256.855.955.854.959.659.058.857.957.757.056.855.855.454.953.452.452.151.551.250.149.649.149.147.747.446.746.345.144.743.144.643.242.741.441.339.839.238.438.336.936.435.333.132.330.329.0
Percentage of Assets25.025.024.224.724.225.024.224.223.823.923.423.423.423.723.022.221.621.420.721.020.120.019.619.718.918.818.118.718.117.716.916.616.216.015.115.214.914.814.50.00.014.814.10.012.70.00.0
Percentage of Assets us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Stockholders Equity Including Portion Attributable To Noncontrolling Interest

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest

mgee:Mge


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value918900871862840795777737714704689676654643632608600600602620640643641612
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets39.939.738.739.338.838.437.435.735.335.234.734.334.534.934.133.633.533.633.535.336.637.237.136.1
Percentage of Assets mgee:Mge42.042.041.141.941.640.339.438.338.038.037.637.337.838.437.637.537.237.236.80.00.00.038.50.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest dei:LegalEntity, us-gaap:StatementEquityComponents

mgee:Mge, us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value252252252252252222222192192192192192192192192192192192192192192192192192
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest27.528.129.029.330.128.028.726.126.927.327.928.429.429.930.431.632.132.031.931.030.029.930.031.4
Percentage of Assets11.011.111.211.511.710.810.79.39.59.69.79.710.210.410.410.610.710.810.710.911.011.111.111.3
Percentage of Assets mgee:Mge us-gaap:AdditionalPaidInCapital0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Mge, us-gaap:NoncontrollingInterest


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value144141141141143138140141141139141138138139140115116115115116142140140125
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest15.815.716.216.317.017.518.019.119.719.820.520.521.221.622.319.019.419.219.218.722.321.921.920.5
Percentage of Assets6.36.26.36.46.66.76.76.87.07.07.17.07.37.67.66.46.56.56.46.68.18.18.17.4
Percentage of Assets mgee:Mge us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Mge, us-gaap:RetainedEarnings


Stockholders
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312014-12-31
Value503488460451426416397386363355338327305294282283273275277294287292291276
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest54.854.252.852.350.852.351.152.450.950.449.148.546.745.844.646.645.645.846.047.545.045.545.545.2
Percentage of Assets21.921.520.420.619.720.119.118.717.917.717.016.616.116.015.215.715.315.415.416.816.516.916.916.3
Percentage of Assets mgee:Mge us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:Atcequitymethodinvesteemember


Stockholders
Period End2020-12-312019-12-31
Value22922214
Percentage of StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest263.0284.8
Percentage of Assets101.7106.4
Percentage of Assets mgee:Atcequitymethodinvesteemember41.741.6

Common Stock Value

us-gaap:CommonStockValue

us-gaap:CommonStockValue


Common
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value363434343434343423232323
Percentage of CommonStockValue100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets1.61.71.71.91.92.02.02.21.51.61.81.8

Additional Paid In Capital

us-gaap:AdditionalPaidInCapital

us-gaap:AdditionalPaidInCapital


Additional
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value394316316316316316316316316316316316
Percentage of AdditionalPaidInCapital100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets17.515.215.917.017.618.318.620.019.921.724.024.7

us-gaap:AdditionalPaidInCapital dei:LegalEntity

mgee:Mge


Additional
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value252222192192192
Percentage of AdditionalPaidInCapital64.170.560.860.860.8
Percentage of Assets11.210.79.710.410.7
Percentage of Assets mgee:Mge11.911.310.511.411.7

Common Stocks Including Additional Paid In Capital

us-gaap:CommonStocksIncludingAdditionalPaidInCapital us-gaap:ConsolidatedEntities

us-gaap:CommonStocksIncludingAdditionalPaidInCapital

srt:ParentCompany


Common
Period End2020-12-312019-12-312018-12-312017-12-31
Value430350350350
Percentage of CommonStocksIncludingAdditionalPaidInCapital100.0100.0100.0100.0
Percentage of Assets19.116.917.618.9
Percentage of Assets srt:ParentCompany42.739.441.343.4

Retained Earnings Accumulated Deficit

us-gaap:RetainedEarningsAccumulatedDeficit

us-gaap:RetainedEarningsAccumulatedDeficit


Retained
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-312009-12-31
Value545504465426372339308266239211185162
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets24.224.223.423.020.719.618.116.915.114.514.112.7

us-gaap:RetainedEarningsAccumulatedDeficit dei:LegalEntity

mgee:Mge


Retained
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value460397338282277
Percentage of RetainedEarningsAccumulatedDeficit84.478.772.766.174.4
Percentage of Assets20.419.117.015.215.4
Percentage of Assets mgee:Mge21.720.118.516.816.9

us-gaap:RetainedEarningsAccumulatedDeficit us-gaap:ConsolidatedEntities

srt:ParentCompany


Retained
Period End2020-12-312019-12-312018-12-312017-12-31
Value545504465426
Percentage of RetainedEarningsAccumulatedDeficit100.0100.0100.0100.0
Percentage of Assets24.224.223.423.0
Percentage of Assets srt:ParentCompany54.156.754.852.8

Minority Interest

us-gaap:MinorityInterest dei:LegalEntity

us-gaap:MinorityInterest

mgee:Mge


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value144141141141143138140141141139141138138139140115116115115
Percentage of MinorityInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets6.36.26.36.46.66.76.76.87.07.07.17.07.37.67.66.46.56.56.4
Percentage of Assets mgee:Mge6.66.66.76.97.17.07.17.37.57.57.77.78.08.38.47.17.27.27.1

mgee:MgePowerElmRoad


Minority
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value9697979780797269697099
Percentage of MinorityInterest68.669.368.969.369.50.00.00.00.00.00.0
Percentage of Assets4.34.74.95.34.54.64.34.44.44.97.5
Percentage of Assets mgee:MgePowerElmRoad0.00.00.00.00.00.00.00.00.00.00.0

mgee:MgePowerWestCampus


Minority
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value4443434335373029303032
Percentage of MinorityInterest31.430.731.130.730.50.00.00.00.00.00.0
Percentage of Assets2.02.12.22.32.02.21.81.81.92.12.5
Percentage of Assets mgee:MgePowerWestCampus0.00.00.00.00.00.00.00.00.00.00.0

Minority Interest Decrease From Distributions To Noncontrolling Interest Holders

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders dei:LegalEntity

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders

mgee:Mge


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.55.05.57.51.57.06.55.54.07.53.05.56.07.51.56.54.55.56.07.5614.0526.5
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets mgee:Mge0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders dei:LegalEntity, us-gaap:StatementEquityComponents

mgee:Mge, us-gaap:NoncontrollingInterest


Minority
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value2.55.05.57.51.57.06.55.54.07.53.05.56.07.51.56.54.55.56.07.5614.0526.5
Percentage of MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of Assets0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0
Percentage of Assets mgee:Mge us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value34433650315318253253144644463331264118354943184938347.7936265831423728305536242439293830
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue26.526.126.737.427.035.913.318.726.831.710.434.035.929.824.222.420.926.313.226.140.929.614.135.331.420.45.326.920.427.820.430.329.217.122.040.030.816.618.529.325.123.118.8

us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value2941344929531623315312444346312925391735
Percentage of NetCashProvidedByUsedInOperatingActivities84.295.794.697.493.398.789.891.996.9100.888.896.197.499.292.394.795.395.895.7100.2
Percentage of RegulatedAndUnregulatedOperatingRevenue22.325.025.236.425.235.412.017.225.932.09.332.635.029.522.421.319.925.212.626.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge22.325.025.236.425.235.412.017.225.932.09.332.635.029.522.421.319.925.212.626.1

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-42.173-35.835-66.052-55.667-39.894-48.799-37.826-51.897-49.755-32.879-64.894-50.363-63.528-39.543-45.247-24.166-28.82-18.128-22.207-22.646-25.477-16.496-20.132-19.38-21.94-11.861-26.925-24.613-21.445-23.175-27.745-29.632-34.729-29.816-33.165-27.357-25.115-15.716-18.462-16.716-18.692-12.481-12.268
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-32.3-21.3-48.4-41.2-34.1-32.6-26.8-37.6-40.7-19.6-46.3-36.5-51.1-25.1-32.3-17.3-22.8-11.6-16.0-16.6-21.0-11.2-15.4-13.8-18.0-7.0-18.5-18.2-16.7-11.0-17.9-21.2-27.1-17.8-24.2-19.8-21.4-10.5-14.1-12.5-15.9-7.6-7.7

us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-41.414-35.208-64.694-54.46-38.943-47.164-35.952-49.503-47.202-32.161-63.621-48.87-62.982-37.829-41.553-22.927-26.219-15.959-21.241-22.379
Percentage of NetCashProvidedByUsedInInvestingActivities98.298.397.997.897.696.695.095.494.997.898.097.099.195.791.894.991.088.095.798.8
Percentage of RegulatedAndUnregulatedOperatingRevenue-31.7-21.0-47.4-40.3-33.3-31.5-25.5-35.8-38.6-19.2-45.4-35.5-50.7-24.0-29.6-16.4-20.7-10.2-15.3-16.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge-31.7-21.0-47.4-40.3-33.3-31.5-25.5-35.8-38.6-19.2-45.4-35.5-50.7-24.0-29.6-16.4-20.7-10.2-15.3-16.4

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1.615-13.58522-14.69462-11.04-18.375174.472-20.8290.1743812-13.28414-5.323-11.776-2.029-11.74-11.755-11.331-11.286-11.281-11.806-11.325-17.831-3.829-10.871-10.443-10.519-10.43920-6.3080.701-9.799-9.828-10.307-9.529-9.509-9.547-9.325-1.981-11.792
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.2-8.116.5-10.953.3-7.4-13.012.73.7-12.40.127.810.4-8.410.3-3.8-9.3-1.3-8.5-8.6-9.3-7.7-8.6-8.4-9.3-10.5-2.6-8.0-8.1-5.0-6.714.4-4.90.4-7.2-7.1-8.8-6.4-7.3-7.1-8.0-1.2-7.4

us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value12-5.20530-8.81324-5.819172412-16.4738.8744418-9.60314-10.603-15.603-11.869-17.091-22.76
Percentage of NetCashProvidedByUsedInFinancingActivities773.738.3134.960.038.552.7-97.1138.7272.279.15100.0116.2140.172.397.8199.2132.5585.0145.6193.6
Percentage of RegulatedAndUnregulatedOperatingRevenue9.6-3.122.3-6.520.5-3.912.717.610.0-9.86.332.314.6-6.110.1-7.6-12.3-7.6-12.3-16.6
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge9.6-3.122.3-6.520.5-3.912.717.610.0-9.86.332.314.6-6.110.1-7.6-12.3-7.6-12.3-16.6

Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-5.908-5.537-7.053-19.854-6.02-37.428-8.58-12.594-0.513-50.11234-5.978-5.8494.0320.092-14.75821
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-4.5-3.3-5.2-14.646.2-4.0-26.6-6.2-10.3-0.3-35.825.2-4.8-3.72.90.1-11.713.5

us-gaap:CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect dei:LegalEntity

mgee:Mge


Cash
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.2471.5680.199-14.047140.135-1.257-1.506-3.3464.968-41.7840-1.424-0.8534.81-5.602-17.23911
Percentage of CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect-4.2-28.3-2.870.927.0-2.23.417.626.6-968.483.4116.923.814.6119.3-6089.1116.855.4
Percentage of RegulatedAndUnregulatedOperatingRevenue0.20.90.1-10.412.50.1-0.9-1.1-2.73.0-29.829.5-1.1-0.53.4-4.0-13.67.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge0.20.90.1-10.412.50.1-0.9-1.1-2.73.0-29.829.5-1.1-0.53.4-4.0-13.67.4

Deferred Income Tax Expense Benefit

us-gaap:DeferredIncomeTaxExpenseBenefit

us-gaap:DeferredIncomeTaxExpenseBenefit


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0.91-0.7961.8993.3763.6551.4332.3482.5583.665-1.3591.3973.0161.129-1.793-8.8923.7734.769-3.7327.385.5196.6822.84141.1692.4783.723259.26615-0.8775.659129.1911
Percentage of DeferredIncomeTaxExpenseBenefit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredIncomeTaxExpenseBenefit dei:LegalEntity

mgee:Mge


Deferred
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.898-1.7661.2093.33.0580.9761.6332.4223.233-2.0020.5111.994-0.345-2.229-10.0152.4044.093-4.2426.8795.1036.3922.502
Percentage of DeferredIncomeTaxExpenseBenefit208.6221.963.797.783.768.169.594.788.2147.336.666.1-30.6124.3112.663.785.8113.793.292.595.788.1

Net Cash Provided By Used In Operating Activities

us-gaap:NetCashProvidedByUsedInOperatingActivities

us-gaap:NetCashProvidedByUsedInOperatingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value34433650315318253253144644463331264118354943184938347.7936265831423728305536242439293830
Percentage of NetCashProvidedByUsedInOperatingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue26.526.126.737.427.035.913.318.726.831.710.434.035.929.824.222.420.926.313.226.140.929.614.135.331.420.45.326.920.427.820.430.329.217.122.040.030.816.618.529.325.123.118.8

us-gaap:NetCashProvidedByUsedInOperatingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value2941344929531623315312444346312925391735
Percentage of NetCashProvidedByUsedInOperatingActivities84.295.794.697.493.398.789.891.996.9100.888.896.197.499.292.394.795.395.895.7100.2
Percentage of RegulatedAndUnregulatedOperatingRevenue22.325.025.236.425.235.412.017.225.932.09.332.635.029.522.421.319.925.212.626.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge22.325.025.236.425.235.412.017.225.932.09.332.635.029.522.421.319.925.212.626.1

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
Value22341531182616301524162918203626151914271617112813181523142714241322102314169.38421121711191114
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 RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.414.812.725.819.112.312.310.420.413.311.58.620.111.010.710.417.310.913.29.117.410.813.57.717.212.210.87.215.810.910.88.815.610.68.9

us-gaap:NetIncomeLoss dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value15288.69324101910238.32216102211128.373198.754128.184211010
Percentage of NetIncomeLoss66.280.955.077.856.673.262.475.553.569.165.175.560.562.223.274.856.366.356.478.862.864.3
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.97.616.28.97.96.014.36.98.25.916.18.37.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge11.616.86.418.39.112.77.416.76.89.97.616.28.97.96.014.36.98.25.916.18.37.4

us-gaap:NetIncomeLoss dei:LegalEntity, us-gaap:ConsolidationItems

mgee:Mge, us-gaap:IntersegmentElimination


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-5.627-5.501-5.639-5.493-5.768-5.493-5.624-5.614-5.621-5.49-5.612-5.629-5.505-5.806-27.013-5.439-5.396-5.389-5.459-5.695-5.952-6.252
Percentage of NetIncomeLoss-24.6-15.7-35.7-17.3-30.7-21.1-33.8-18.3-36.2-22.9-34.3-19.1-30.0-29.0-74.8-20.4-34.7-27.9-37.6-20.4-36.9-36.7
Percentage of RegulatedAndUnregulatedOperatingRevenue-4.3-3.3-4.1-4.1-4.9-3.7-4.0-4.1-4.6-3.3-4.0-4.1-4.4-3.7-19.3-3.9-4.3-3.4-3.9-4.2-4.9-4.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:IntersegmentElimination43.236.142.739.845.740.141.035.346.436.340.339.942.040.9189.636.537.435.135.132.633.837.9

mgee:Mge, us-gaap:OperatingSegments


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value15288.69324101910238.32216
Percentage of NetIncomeLoss66.280.955.077.856.673.262.475.553.569.1
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.9
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments11.616.86.418.39.112.77.416.76.89.9

us-gaap:NetIncomeLoss dei:LegalEntity, us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

mgee:Mge, us-gaap:OperatingSegments, mgee:Electric


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value14184.0832410115.413237.8769.3496.78522106.1324.883198.6537.9534.948218.535.992
Percentage of NetIncomeLoss61.851.625.877.954.444.032.577.250.738.941.576.956.330.713.574.755.741.234.175.652.835.2
Percentage of RegulatedAndUnregulatedOperatingRevenue10.810.73.018.38.77.63.817.16.45.64.816.58.33.93.514.36.85.13.615.47.04.1
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Electric13.917.94.521.210.912.35.819.68.19.67.719.010.56.55.316.58.58.15.117.78.56.4

mgee:Mge, us-gaap:OperatingSegments, mgee:Gas


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.277104.9510.2210.968.0345.44-0.0610.9517.764.410.1761.2896.9914.1450.6840.7845.5322.8340.9721.785.037
Percentage of NetIncomeLoss5.630.231.30.75.130.932.6-0.26.132.327.00.67.035.011.52.65.028.719.53.511.029.6
Percentage of RegulatedAndUnregulatedOperatingRevenue1.06.33.60.20.85.43.9-0.00.84.63.10.11.04.43.00.50.63.52.00.71.53.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:Gas4.014.610.21.03.813.310.7-0.33.510.37.90.84.510.48.23.02.98.86.14.16.68.5

mgee:Mge, us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.3555.1945.2985.2515.2255.065.1625.1315.1164.9615.0665.0564.9785.133264.7674.7134.6984.7634.7354.7254.833
Percentage of NetIncomeLoss23.414.933.516.527.819.431.016.732.920.731.017.127.125.772.917.930.324.332.817.029.328.4
Percentage of RegulatedAndUnregulatedOperatingRevenue4.13.13.93.94.53.43.73.74.23.03.63.74.03.318.83.43.73.03.43.53.93.3
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:OperatingSegments mgee:NonRegulatedEnergy51.450.951.150.950.750.150.450.150.149.549.949.949.549.9234.342.442.142.242.342.242.242.2

us-gaap:NetIncomeLoss us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, mgee:Electric


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value14184.0832410115.413237.8769.3496.78522106.1324.883198.6537.9534.948218.535.9923.16206.276.1115.933187.382103.571197.0867.016
Percentage of NetIncomeLoss61.851.625.877.954.444.032.577.250.738.941.576.956.330.713.574.755.741.234.175.652.835.228.173.546.533.439.177.452.436.125.478.051.031.1
Percentage of RegulatedAndUnregulatedOperatingRevenue10.810.73.018.38.77.63.817.16.45.64.816.58.33.93.514.36.85.13.615.47.04.12.414.85.13.64.113.45.74.82.313.65.54.2
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Electric13.917.94.521.210.912.35.819.68.19.67.719.010.56.55.316.58.58.15.117.78.56.43.417.16.36.26.916.07.610.13.815.87.37.5

us-gaap:OperatingSegments, mgee:Gas


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value1.277104.9510.2210.968.0345.44-0.0610.9517.764.410.1761.2896.9914.1450.6840.7845.5322.8340.9721.785.0372.351.1230.8376.0574.773-0.9050.485115.407-1.2470.3018.976
Percentage of NetIncomeLoss5.630.231.30.75.130.932.6-0.26.132.327.00.67.035.011.52.65.028.719.53.511.029.620.94.06.233.131.4-3.93.441.238.4-5.12.239.7
Percentage of RegulatedAndUnregulatedOperatingRevenue1.06.33.60.20.85.43.9-0.00.84.63.10.11.04.43.00.50.63.52.00.71.53.41.80.80.73.63.3-0.70.45.43.5-0.90.25.4
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:Gas4.014.610.21.03.813.310.7-0.33.510.37.90.84.510.48.23.02.98.86.14.16.68.56.15.33.68.38.0-3.91.510.08.7-5.80.911.6

us-gaap:OperatingSegments, mgee:NonRegulatedEnergy


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value5.3555.1945.2985.2515.2255.065.1625.1315.1164.9615.0665.0564.9785.133264.7674.7134.6984.7634.7354.7254.8335.0245.0165.045.0184.8734.8474.8374.7325.1815.1735.1965.143
Percentage of NetIncomeLoss23.414.933.516.527.819.431.016.732.920.731.017.127.125.772.917.930.324.332.817.029.328.444.717.737.427.532.120.834.317.136.821.237.422.8
Percentage of RegulatedAndUnregulatedOperatingRevenue4.13.13.93.94.53.43.73.74.23.03.63.74.03.318.83.43.73.03.43.53.93.33.83.64.12.93.33.63.82.33.33.74.13.1
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:NonRegulatedEnergy51.450.951.150.950.750.150.450.150.149.549.949.949.549.9234.342.442.142.242.342.242.242.242.742.642.642.542.142.042.041.743.042.943.043.4

us-gaap:OperatingSegments, mgee:TransmissionInvestment


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value1.7931.7781.7751.712.2851.6631.9931.7261.6481.5771.9561.1751.3891.7211.5571.3431.51.4811.9881.1981.0551.3350.6911.421.3711.1251.1041.461.4391.4831.431.41.3821.425
Percentage of NetIncomeLoss7.85.111.25.412.26.412.05.610.66.612.04.07.68.64.35.09.77.713.74.36.57.86.25.010.26.27.36.310.25.410.25.79.96.3
Percentage of RegulatedAndUnregulatedOperatingRevenue1.41.11.31.32.01.11.41.21.30.91.40.91.11.11.11.01.20.91.40.90.90.90.51.01.10.70.81.11.10.70.91.01.10.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments mgee:TransmissionInvestment0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:OperatingSegments, us-gaap:CorporateAndOther


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value0.304-0.619-0.311-0.1490.105-0.183-1.3460.18-0.0430.36-1.8560.4150.3590.024-0.809-0.067-0.107-0.364-0.031-0.1080.06-0.1690.007-0.057-0.039-0.033-1.497-0.14-0.0560.074-1.5120.022-0.0740.024
Percentage of NetIncomeLoss1.3-1.8-2.0-0.50.6-0.7-8.10.6-0.31.5-11.31.42.00.1-2.2-0.3-0.7-1.9-0.2-0.40.4-1.00.1-0.2-0.3-0.2-9.9-0.6-0.40.3-10.70.1-0.50.1
Percentage of RegulatedAndUnregulatedOperatingRevenue0.2-0.4-0.2-0.10.1-0.1-1.00.1-0.00.2-1.30.30.30.0-0.6-0.0-0.1-0.2-0.0-0.10.0-0.10.0-0.0-0.0-0.0-1.0-0.1-0.00.0-1.00.0-0.10.0
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:OperatingSegments us-gaap:CorporateAndOther0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:NetIncomeLoss us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value22341531182616301524162918203626151914271617112813181523142714241322102314169.38421121714
Percentage of NetIncomeLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.414.812.725.819.112.312.310.420.413.311.58.620.111.010.710.417.310.913.29.117.410.813.57.717.212.210.87.215.810.910.88.9
Percentage of RegulatedAndUnregulatedOperatingRevenue us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Profit Loss

us-gaap:ProfitLoss

us-gaap:ProfitLoss


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-30
Value223415311826163015241629
Percentage of ProfitLoss100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue17.520.811.623.516.117.411.822.212.714.311.721.4

us-gaap:ProfitLoss dei:LegalEntity

mgee:Mge


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value20331430162416281322162716183525141813271617
Percentage of ProfitLoss90.896.790.795.187.394.396.193.889.791.999.494.60.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue15.920.110.522.414.016.411.420.811.413.211.620.313.411.625.218.211.211.69.820.213.211.7
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge15.920.110.522.414.016.411.420.811.413.211.620.313.411.625.218.211.211.69.820.213.211.7

us-gaap:ProfitLoss dei:LegalEntity, us-gaap:StatementEquityComponents

mgee:Mge, us-gaap:NoncontrollingInterest


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.6275.5015.6395.4935.7685.4935.6245.6145.6215.495.6125.6295.5055.806275.4395.3965.3895.4595.6955.9526.252
Percentage of ProfitLoss24.615.735.717.330.721.133.818.336.222.934.319.10.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue4.33.34.14.14.93.74.04.14.63.34.04.14.43.719.33.94.33.43.94.24.94.2
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:NoncontrollingInterest0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

mgee:Mge, us-gaap:RetainedEarnings


Profit
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value15288.69324101910238.32216102211128.373198.754128.184211010
Percentage of ProfitLoss66.280.955.077.856.673.262.475.553.569.165.175.50.00.00.00.00.00.00.00.00.00.0
Percentage of RegulatedAndUnregulatedOperatingRevenue11.616.86.418.39.112.77.416.76.89.97.616.28.97.96.014.36.98.25.916.18.37.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge us-gaap:RetainedEarnings0.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

Net Cash Provided By Used In Investing Activities

us-gaap:NetCashProvidedByUsedInInvestingActivities

us-gaap:NetCashProvidedByUsedInInvestingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-42.173-35.835-66.052-55.667-39.894-48.799-37.826-51.897-49.755-32.879-64.894-50.363-63.528-39.543-45.247-24.166-28.82-18.128-22.207-22.646-25.477-16.496-20.132-19.38-21.94-11.861-26.925-24.613-21.445-23.175-27.745-29.632-34.729-29.816-33.165-27.357-25.115-15.716-18.462-16.716-18.692-12.481-12.268
Percentage of NetCashProvidedByUsedInInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue-32.3-21.3-48.4-41.2-34.1-32.6-26.8-37.6-40.7-19.6-46.3-36.5-51.1-25.1-32.3-17.3-22.8-11.6-16.0-16.6-21.0-11.2-15.4-13.8-18.0-7.0-18.5-18.2-16.7-11.0-17.9-21.2-27.1-17.8-24.2-19.8-21.4-10.5-14.1-12.5-15.9-7.6-7.7

us-gaap:NetCashProvidedByUsedInInvestingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-41.414-35.208-64.694-54.46-38.943-47.164-35.952-49.503-47.202-32.161-63.621-48.87-62.982-37.829-41.553-22.927-26.219-15.959-21.241-22.379
Percentage of NetCashProvidedByUsedInInvestingActivities98.298.397.997.897.696.695.095.494.997.898.097.099.195.791.894.991.088.095.798.8
Percentage of RegulatedAndUnregulatedOperatingRevenue-31.7-21.0-47.4-40.3-33.3-31.5-25.5-35.8-38.6-19.2-45.4-35.5-50.7-24.0-29.6-16.4-20.7-10.2-15.3-16.4
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge-31.7-21.0-47.4-40.3-33.3-31.5-25.5-35.8-38.6-19.2-45.4-35.5-50.7-24.0-29.6-16.4-20.7-10.2-15.3-16.4

Payments To Acquire Property Plant And Equipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value40346453384635494731634862374124261621212515191921112623202126283329322624152016189.84314
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquirePropertyPlantAndEquipment dei:LegalEntity

mgee:Mge


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
Value40346453384635494731634862374124261621212515
Percentage of PaymentsToAcquirePropertyPlantAndEquipment100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Net Cash Provided By Used In Financing Activities

us-gaap:NetCashProvidedByUsedInFinancingActivities

us-gaap:NetCashProvidedByUsedInFinancingActivities


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1.615-13.58522-14.69462-11.04-18.375174.472-20.8290.1743812-13.28414-5.323-11.776-2.029-11.74-11.755-11.331-11.286-11.281-11.806-11.325-17.831-3.829-10.871-10.443-10.519-10.43920-6.3080.701-9.799-9.828-10.307-9.529-9.509-9.547-9.325-1.981-11.792
Percentage of NetCashProvidedByUsedInFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0
Percentage of RegulatedAndUnregulatedOperatingRevenue1.2-8.116.5-10.953.3-7.4-13.012.73.7-12.40.127.810.4-8.410.3-3.8-9.3-1.3-8.5-8.6-9.3-7.7-8.6-8.4-9.3-10.5-2.6-8.0-8.1-5.0-6.714.4-4.90.4-7.2-7.1-8.8-6.4-7.3-7.1-8.0-1.2-7.4

us-gaap:NetCashProvidedByUsedInFinancingActivities dei:LegalEntity

mgee:Mge


Net
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value12-5.20530-8.81324-5.819172412-16.4738.8744418-9.60314-10.603-15.603-11.869-17.091-22.76
Percentage of NetCashProvidedByUsedInFinancingActivities773.738.3134.960.038.552.7-97.1138.7272.279.15100.0116.2140.172.397.8199.2132.5585.0145.6193.6
Percentage of RegulatedAndUnregulatedOperatingRevenue9.6-3.122.3-6.520.5-3.912.717.610.0-9.86.332.314.6-6.110.1-7.6-12.3-7.6-12.3-16.6
Percentage of RegulatedAndUnregulatedOperatingRevenue mgee:Mge9.6-3.122.3-6.520.5-3.912.717.610.0-9.86.332.314.6-6.110.1-7.6-12.3-7.6-12.3-16.6

Proceeds From Issuance Of Long Term Debt

us-gaap:ProceedsFromIssuanceOfLongTermDebt

us-gaap:ProceedsFromIssuanceOfLongTermDebt


Proceeds
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312014-12-312013-12-312013-09-302012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value0.00.0500.00.01000.00.0300.00.0400.00.00.00.00.00.0850.00.0280.00.00.00.03050
Percentage of ProceedsFromIssuanceOfLongTermDebt0.00.0100.00.00.0100.00.00.0100.00.00.0100.00.00.00.00.00.00.0100.00.00.0100.00.00.00.00.0100.0100.0

us-gaap:ProceedsFromIssuanceOfLongTermDebt dei:LegalEntity

mgee:Mge


Proceeds
Period End2020-12-312020-09-302019-12-312019-09-302018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value0.00.0500.00.01000.00.0300.00.0400.00.00.00.0
Percentage of ProceedsFromIssuanceOfLongTermDebt0.00.0100.00.00.0100.00.00.0100.00.00.0100.00.00.00.00.0

Repayments Of Long Term Debt

us-gaap:RepaymentsOfLongTermDebt

us-gaap:RepaymentsOfLongTermDebt


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1.1891.182161.168201.1551.1481.1421.1341.1291.123211.111.1031.0981.0931.087311.0751.0691.0641.0591.0541.0481.0431.0371.0341.0271.0231.0191.012400.6660.6670.6680.666280.6670.6660.6670.6670.50.277
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RepaymentsOfLongTermDebt dei:LegalEntity

mgee:Mge


Repayments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.1891.182161.168201.1551.1481.1421.1341.1291.123211.111.1031.0981.0931.087311.0751.0691.0641.059
Percentage of RepaymentsOfLongTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Payments Of Dividends Common Stock

us-gaap:PaymentsOfDividendsCommonStock

us-gaap:PaymentsOfDividendsCommonStock


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1313131312121212111111111111111110101010101010109.7959.7949.7959.7949.429.429.4229.4219.1329.1329.1319.1338.8448.8438.8438.8438.678.678.515
Percentage of PaymentsOfDividendsCommonStock100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

Effective Income Tax Rate Continuing Operations

us-gaap:EffectiveIncomeTaxRateContinuingOperations

us-gaap:EffectiveIncomeTaxRateContinuingOperations


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value3.71.318.70.1660.161-0.0060.1960.1840.1920.0030.2450.2410.242-0.1810.3690.360.367-0.0040.3610.3650.3690.0060.3510.3730.367-0.0030.380.3910.37-0.0030.3760.3840.37700.3760.3760.381-0.0020.3730.3730.375
Percentage of EffectiveIncomeTaxRateContinuingOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateContinuingOperations dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.4-1.317.90.1570.151-0.0070.1890.1760.1830.0030.2460.2390.234-0.1930.3670.3550.362-0.0050.360.3650.368
Percentage of EffectiveIncomeTaxRateContinuingOperations37.8-100.095.794.693.8116.796.495.795.3100.0100.499.296.7106.699.598.698.6125.099.7100.099.7

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Grants In Period

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod us-gaap:AwardType, us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod

us-gaap:PerformanceShares, mgee:Longtermincentiveplan2021


Share
Period End2021-02-19
Value10187.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod100.0

us-gaap:RestrictedStockUnitsRSU, mgee:Longtermincentiveplan2021


Share
Period End2021-02-19
Value16267.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod159.7

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod us-gaap:AwardType, us-gaap:PlanName, us-gaap:SubsequentEventType

us-gaap:PerformanceShares, mgee:LongTermIncentivePlan2021, us-gaap:SubsequentEvent


Share
Period End2021-02-19
Value10187.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod100.0

us-gaap:RestrictedStockUnitsRSU, mgee:LongTermIncentivePlan2021, us-gaap:SubsequentEvent


Share
Period End2021-02-19
Value16267.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod159.7

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod us-gaap:PlanName

mgee:DirectorIncentiveAgreement


Share
Period End2020-12-312020-09-302020-06-302020-03-31
Value0005048.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod0.00.00.00.0

Deferred Tax Liabilities

us-gaap:DeferredTaxLiabilities

us-gaap:DeferredTaxLiabilities


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312012-12-312011-12-312010-12-31
Value231243231225383360408321260
Percentage of DeferredTaxLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxLiabilities dei:LegalEntity

mgee:Mge


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value200214204201343
Percentage of DeferredTaxLiabilities86.688.088.289.589.4

mgee:MgePowerElmRoad


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
Value3030302942404034561511
Percentage of DeferredTaxLiabilities13.212.613.213.011.111.30.00.013.84.84.2

mgee:MgePowerWestCampus


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
Value1414141319192323212019
Percentage of DeferredTaxLiabilities6.35.96.16.15.25.40.00.05.26.47.7

Deferred Tax Assets Net

us-gaap:DeferredTaxAssetsNet

us-gaap:DeferredTaxAssetsNet


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value1531291341321421091108116111891
Percentage of DeferredTaxAssetsNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsNet dei:LegalEntity

mgee:Mge


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value132107111107111
Percentage of DeferredTaxAssetsNet86.582.782.581.378.1

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
Value2281000.02093000.01949000.01924000.02487000.02528000.02365000.02363000.03204000.02364000.04377000.0176000.0176000.0
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 End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312012-12-312011-12-312010-12-31
Value38000.086000.086000.086000.069000.070000.070000.0195000.0365000.0365000.0365000.0
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DeferredTaxAssetsValuationAllowance dei:LegalEntity

mgee:Mge


Deferred
Period End2020-12-312019-12-312018-12-312017-12-312016-12-31
Value38000.086000.086000.086000.069000.0
Percentage of DeferredTaxAssetsValuationAllowance100.0100.0100.0100.0100.0

Proceeds From Repayments Of Short Term Debt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt

us-gaap:ProceedsFromRepaymentsOfShortTermDebt


Proceeds
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-23.01.5-3.03.0-54.53117-7.013-28.225-1.0-3.07.00.00.00.00.00.00.00.00.00.0-7.07.00.00.00.03.5100.00.00.00.00.00.00.0-22.5-53.0
Percentage of ProceedsFromRepaymentsOfShortTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.00.00.00.00.00.0100.0100.00.00.00.0100.0100.00.00.00.00.00.00.00.0100.0100.0

us-gaap:ProceedsFromRepaymentsOfShortTermDebt dei:LegalEntity

mgee:Mge


Proceeds
Period End2021-06-302021-03-312020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-31
Value-23.01.5-3.03.0-54.53117-7.013-28.225-1.0-3.07.00.00.00.0
Percentage of ProceedsFromRepaymentsOfShortTermDebt100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.0

mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMinimumAnnualRateCompoundedMonthly us-gaap:InvestmentType

mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMinimumAnnualRateCompoundedMonthly

us-gaap:USTreasuryBillSecurities


Deferred
Period End2021-06-302021-03-31
Value07.0
Percentage of DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMinimumAnnualRateCompoundedMonthly0.0100.0

mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMonthlyCompoundingRate us-gaap:InvestmentType

mgee:DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMonthlyCompoundingRate

us-gaap:USTreasuryBillSecurities


Deferred
Period End2021-06-302021-03-31
Value01.0
Percentage of DeferredCompensationArrangementWithIndividualInvestmentInterestCalculationMonthlyCompoundingRate0.0100.0

mgee:DeferredSavingsFromCurrentYearEmployeeBenefitCosts

mgee:DeferredSavingsFromCurrentYearEmployeeBenefitCosts


Deferred
Period End2021-06-30
Value2600000.0
Percentage of DeferredSavingsFromCurrentYearEmployeeBenefitCosts100.0

mgee:DefinedBenefitPlanDeferredNetPeriodicBenefitCosts

mgee:DefinedBenefitPlanDeferredNetPeriodicBenefitCosts


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-200000.0-3400000.0-200000.0-200000.0-200000.0-400000.01600000.01300000.03000000.00
Percentage of DefinedBenefitPlanDeferredNetPeriodicBenefitCosts100.0100.0100.0100.0100.0100.0100.0100.0100.00.0

mgee:DerivativeNonmonetaryNotionalAmountDecathermMeasure us-gaap:DerivativeInstrumentRisk

mgee:DerivativeNonmonetaryNotionalAmountDecathermMeasure

us-gaap:CommodityContract


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value3590000.02190000.0-2465000.01215000.02630000.04650000.0-2585000.02050000.04268200.02871800.0-3297000.02554500.02732500.03270000.0-2464500.03143000.03104000.01677500.0-1962500.04270000.0-430000.02317500.0-1510000.02498200.01264300.02785000.0-2150000.02172500.02182500.02200000.0
Percentage of DerivativeNonmonetaryNotionalAmountDecathermMeasure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:DerivativeNonmonetaryNotionalAmountPowerMeasure us-gaap:DerivativeInstrumentRisk

mgee:DerivativeNonmonetaryNotionalAmountPowerMeasure

mgee:FinancialTransmissionRights


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value3389.01152.0-1720.0-1697.05178.01108.0-1532.0-1571.05009.0844.0-1429.0-1645.04440.0886.0-1326.0-1539.04171.0920.0-1316.0-2086.04883.0770.0-1286.0-2123.04718.0691.0-1250.0-1493.03807.0790.0
Percentage of DerivativeNonmonetaryNotionalAmountPowerMeasure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:PurchasedPowerAgreement


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value-150.0700.0-150.0-150.0-150.01300.0-150.0-150.0-150.01900.0-150.0-150.0-150.02500.0-150.0-150.0-150.03100.0
Percentage of DerivativeNonmonetaryNotionalAmountPowerMeasure-4.460.88.78.8-2.9117.39.89.5-3.0225.110.59.1-3.4282.211.39.7-3.6337.0

mgee:DerivativeRealizedGainLossDeferred us-gaap:BalanceSheetLocation

mgee:DerivativeRealizedGainLossDeferred

mgee:RegulatoryAsset


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value366000.050000.0233000.0207000.0729000.01063000.0494000.0411000.0731000.0260000.0-1360000.0316000.0363000.0158000.0325000.0313000.0544000.078000.0-357000.0-17000.0-17000.01451000.01253000.0408000.0231000.01061000.0525000.0314000.0101000.0-1535000.0-130000.0275000.0388000.0290000.0-246000.0223000.0222000.0
Percentage of DerivativeRealizedGainLossDeferred100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCurrentAssets


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value-366000.0-50000.0-233000.0-207000.0-729000.0-1063000.0-494000.0-411000.0-731000.0-260000.01360000.0-316000.0-363000.0-158000.0-325000.0-313000.0-544000.0-78000.0357000.017000.017000.0-1451000.0-1253000.0-408000.0-231000.0-1061000.0-525000.0-314000.0-101000.01535000.0130000.0-275000.0-388000.0-290000.0246000.0-223000.0-222000.0
Percentage of DerivativeRealizedGainLossDeferred-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0-100.0

mgee:EquityMethodInvestmentSummarizedFinancialInformationInterestIncomeExpense us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:EquityMethodInvestmentSummarizedFinancialInformationInterestIncomeExpense

mgee:ATCequitymethodinvesteemember


Equity
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value-28792000.0-28871000.0-28801000.0-26258000.0-28888000.0-29165000.0-28838000.0-29118000.0-27754000.0-26895000.0-27762000.0-28273000.0-26299000.0-26616000.0-24624000.0-24882000.0-24208000.0-23655000.0
Percentage of EquityMethodInvestmentSummarizedFinancialInformationInterestIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLossBeforeTaxes us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLossBeforeTaxes

mgee:ATCequitymethodinvesteemember


Equity
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value656566806361605855485258686554486163
Percentage of EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLossBeforeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:EquityMethodInvestmentSummarizedFinancialInformationOtherIncomeExpense us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:EquityMethodInvestmentSummarizedFinancialInformationOtherIncomeExpense

mgee:ATCequitymethodinvesteemember


Equity
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value663000.0378000.0643000.0906000.0375000.0484000.0287000.0260000.0439000.01520000.0111000.0796000.0612000.0207000.01128000.01308000.0127000.0585000.0
Percentage of EquityMethodInvestmentSummarizedFinancialInformationOtherIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:ExcessDeferredTaxIncomeStatementEffect us-gaap:IncomeTaxAuthority

mgee:ExcessDeferredTaxIncomeStatementEffect

mgee:ExcessDeferredTaxesTaxCutsAndJobsAct


Excess
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-31
Value700000.0700000.0200000.0700000.0700000.0700000.0900000.0600000.0500000.0600000.0700000.0500000.0400000.0500000.0
Percentage of ExcessDeferredTaxIncomeStatementEffect100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:FairValueInputsCounterpartyFuelMixInternalGeneration us-gaap:Range

mgee:FairValueInputsCounterpartyFuelMixInternalGeneration

srt:Maximum


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.660000.650000.60
Percentage of FairValueInputsCounterpartyFuelMixInternalGeneration0.0100.00.00.00.0100.00.00.00.0100.00.0

srt:Minimum


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.410000.460000.40
Percentage of FairValueInputsCounterpartyFuelMixInternalGeneration0.062.10.00.00.070.80.00.00.066.70.0

srt:WeightedAverage


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value-0.656.90.155.8370.0040.559
Percentage of FairValueInputsCounterpartyFuelMixInternalGeneration0.08621.20.00.00.086.0

mgee:FairValueInputsCounterpartyFuelMixPurchasedPower us-gaap:Range

mgee:FairValueInputsCounterpartyFuelMixPurchasedPower

srt:Maximum


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.590000.540000.60
Percentage of FairValueInputsCounterpartyFuelMixPurchasedPower0.0100.00.00.00.0100.00.00.00.0100.00.0

srt:Minimum


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-31
Value00.340000.350000.40
Percentage of FairValueInputsCounterpartyFuelMixPurchasedPower0.057.60.00.00.064.80.00.00.066.70.0

srt:WeightedAverage


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-31
Value0.643.1-0.143.163-0.0040.441
Percentage of FairValueInputsCounterpartyFuelMixPurchasedPower0.07305.10.00.00.081.7

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOffPeak

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOffPeak


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value-0.195.00.892.7620.0030.935-0.0010.0010.0020.925-0.0040.00100.931-0.001-0.0050.0070.94-0.007-0.006-0.0120.959-0.00300.0070.9470.006
Percentage of FairValueInputsDeliveryPointsBasisAdjustmentOffPeak100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOnPeak

mgee:FairValueInputsDeliveryPointsBasisAdjustmentOnPeak


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-31
Value0.194.40.392.9620.010.928-0.00100.0010.9210.0020.008-0.0060.917-0.001-0.0040.0060.922-0.014-0.016-0.0180.967-0.005-0.0020.0010.9750.006
Percentage of FairValueInputsDeliveryPointsBasisAdjustmentOnPeak100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets


Fair
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value-180000.0355000.0-37000.0-311000.0247000.04000.0-376000.0173000.0-25000.0-297000.0-173000.0-14000.0-222000.0125000.00000
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInCurrentAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.00.00.0

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets

mgee:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets


Fair
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value6.8342.6885.2964.6240.814.317-2.0540.7192.0184.130.5632.8462.7481.9531.4555.218-3.6-0.888
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInRegulatoryLiabilitiesAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:InterestExpenseAndOtherIncomeNet

mgee:InterestExpenseAndOtherIncomeNet


Interest
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-31
Value454000.0769000.01011000.0-390000.0-2099000.0-627000.0-730000.0-796000.0-1987000.0-695000.0-52000.0180000.0-3533000.0-788000.0-2272000.0-2443000.0-1886000.0-2933000.0-2778000.0-2558000.0-3529000.0-2472000.0-2562000.0-2986000.0-5780000.0-2505000.0-1320000.011000.0-4056000.0-855000.0-1946000.0-1366000.0-2656000.0-1993000.0-2215000.0-2534000.0
Percentage of InterestExpenseAndOtherIncomeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:PaymentsForDistributionsToParentFromNoncontrollingInterest dei:LegalEntity

mgee:PaymentsForDistributionsToParentFromNoncontrollingInterest

mgee:Mge


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
Value2.55.05.57.51.57.06.55.54.07.53.05.56.07.51.56.54.55.56.07.5614.0526.5
Percentage of PaymentsForDistributionsToParentFromNoncontrollingInterest100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity

mgee:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity


Public
Period End2020-09-302020-06-302019-09-302019-06-30
Value1900000.01400000.0700000.0100000.0
Percentage of PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity100.0100.0100.0100.0

mgee:PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity us-gaap:JointlyOwnedUtilityPlant

mgee:BadgerHollowIandII


Public
Period End2021-06-302021-03-312020-06-302020-03-31
Value1200000.01100000.0500000.0400000.0
Percentage of PublicUtilitiesAllowanceForFundsUsedDuringConstructionCapitalizedInterestAndCostOfEquity0.00.035.70.0

mgee:UtilitiesOperatingExpenseCostOfGasSold

mgee:UtilitiesOperatingExpenseCostOfGasSold


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value1137223.8126.33930243.0928.87543304.9219.56239265.0949.23135234.3146.4132184.2996.654635111878378.8191644287.3897.80134278.1711350
Percentage of UtilitiesOperatingExpenseCostOfGasSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:UtilitiesOperatingExpenseCostOfGasSold dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1137223.8126.33930243.0928.87543304.9219.56239265.0949.2335234.326.41532
Percentage of UtilitiesOperatingExpenseCostOfGasSold100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.1100.1100.0

us-gaap:AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease

us-gaap:AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease


Allowance
Period End2020-12-312020-09-302020-06-30
Value1700000.01100000.01500000.0
Percentage of AllowanceForDoubtfulAccountsReceivablePeriodIncreaseDecrease100.0100.0100.0

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs

us-gaap:AllowanceForDoubtfulAccountsReceivableWriteOffs


Allowance
Period End2020-12-312020-09-302020-06-30
Value500000.0300000.0100000.0
Percentage of AllowanceForDoubtfulAccountsReceivableWriteOffs100.0100.0100.0

us-gaap:CapitalExpendituresIncurredButNotYetPaid

us-gaap:CapitalExpendituresIncurredButNotYetPaid


Capital
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value3.5838.843-17.8757.8327.6338.1299.87814-1.1643.4280.1384.5241.7614.7064.1334.0191.6466.8045.7733.5120.5046.5870.4661.088-4.98-2.8930.4758.967-0.581-2.7760.55122.6682.870.1054.674-1.9221.643-0.1831.146
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:CapitalExpendituresIncurredButNotYetPaid dei:LegalEntity

mgee:Mge


Capital
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value3.5838.843-17.8757.8327.6338.1299.87814-1.1643.4280.1384.5241.7614.7064.1334.0191.6466.8045.7733.5120.5046.587
Percentage of CapitalExpendituresIncurredButNotYetPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:CommonStockDividendsPerShareCashPaid

us-gaap:CommonStockDividendsPerShareCashPaid


Common
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-12-312010-09-302010-06-302010-03-31
Value0.370.370.370.3530.3530.3530.3530.3380.3380.3380.3380.3230.3230.3230.3230.3080.3080.3080.3080.2950.2950.2950.2950.2830.2830.2830.2830.2720.2720.2720.4080.3950.3950.3950.3950.3830.3830.3830.3830.3750.3750.3750.3750.3680.368
Percentage of CommonStockDividendsPerShareCashPaid100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfGainsLosses

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-138000.0-109000.0-52000.0-55000.0-40000.0-70000.0-101000.0-100000.0-94000.0-106000.0-122000.0-122000.0-116000.0-128000.0-90000.0-190000.0-251000.0-129000.0-56000.0-178000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-1743000.0-1580000.0-1339000.0-1339000.0-1392000.0-1286000.0-2028000.0-1637000.0-1985000.0-1729000.0-1320000.0-1319000.0-1341000.0-1298000.0-1583000.0-1594000.0-1711000.0-1464000.0-1322000.0-1388000.0
Percentage of DefinedBenefitPlanAmortizationOfGainsLosses1263.01449.52575.02434.53480.01837.12007.91637.02111.71631.11082.01081.11156.01014.11758.9838.9681.71134.92360.7779.8

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfPriorServiceCostCredit

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-380000.0-380000.0-668000.0-667000.0-667000.0-667000.0-675000.0-664000.0-662000.0-667000.0-668000.0-667000.0-667000.0-667000.0-668000.0-667000.0-898000.0-436000.0-436000.0-744000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-31000.0-31000.0-21000.0-31000.0-31000.0-31000.0-32000.0-26000.0-31000.0-28000.0-11000.0-11000.0-11000.0-11000.0-5000.0-4000.0-4000.0-4000.02000.03000.0
Percentage of DefinedBenefitPlanAmortizationOfPriorServiceCostCredit8.28.23.14.64.64.64.73.94.74.21.61.61.61.60.70.60.40.9-0.5-0.4

us-gaap:DefinedBenefitPlanAmortizationOfTransitionAssetObligation us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanAmortizationOfTransitionAssetObligation

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.0-1000.00-1000.0-1000.0-1000.0-1000.000-1000.0
Percentage of DefinedBenefitPlanAmortizationOfTransitionAssetObligation100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.00.0100.0

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanExpectedReturnOnPlanAssets

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value0.8210.8170.7880.7890.7870.790.6890.6770.6760.6810.8080.8080.8140.8020.7220.7220.9710.4720.4690.787
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value7.3687.3756.8076.8076.8046.8116.2635.0545.9225.5476.5616.566.5526.5685.7195.7625.745.7424.7195.724
Percentage of DefinedBenefitPlanExpectedReturnOnPlanAssets897.4902.7863.8862.7864.5862.2909.0746.5876.0814.5812.0811.9804.9819.0792.1798.1591.11216.51006.2727.3

us-gaap:DefinedBenefitPlanInterestCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanInterestCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value0.390.3840.5690.570.5660.5730.7290.7210.8650.5770.6530.6530.6480.6580.6320.6780.9120.4440.4230.753
Percentage of DefinedBenefitPlanInterestCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value2.2882.2723.0533.0523.0823.0233.9383.173.7423.4523.2143.2153.2223.2083.1443.1683.1943.1192.6493.161
Percentage of DefinedBenefitPlanInterestCost586.7591.7536.6535.4544.5527.6540.2439.7432.6598.3492.2492.3497.2487.5497.5467.3350.2702.5626.2419.8

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanNetPeriodicBenefitCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-0.299-0.352-0.518-0.514-0.526-0.502-0.252-0.243-0.044-0.445-0.379-0.379-0.407-0.35-0.38-0.205-0.282-0.129-0.239-0.238
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value-1.926-2.132-1.112-1.123-1.029-1.2170.9610.7670.9950.747-0.607-0.606-0.596-0.6160.3430.3470.5210.1690.2610.241
Percentage of DefinedBenefitPlanNetPeriodicBenefitCost644.1605.7214.7218.5195.6242.4-381.3-315.6-2261.4-167.9160.2159.9146.4176.0-90.3-169.3-184.8-131.0-109.2-101.3

us-gaap:DefinedBenefitPlanServiceCost us-gaap:RetirementPlanType

us-gaap:DefinedBenefitPlanServiceCost

us-gaap:OtherPostretirementBenefitPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value373000.0351000.0316000.0316000.0321000.0311000.0281000.0276000.0334000.0219000.0321000.0320000.0310000.0332000.0287000.0315000.0423000.0206000.0187000.0361000.0
Percentage of DefinedBenefitPlanServiceCost100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionPlansDefinedBenefit


Defined
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-30
Value1442000.01422000.01324000.01324000.01332000.01316000.01290000.01040000.01221000.01141000.01431000.01431000.01404000.01457000.01340000.01351000.01360000.01332000.01007000.01413000.0
Percentage of DefinedBenefitPlanServiceCost386.6405.1419.0419.0415.0423.2459.1376.8365.6521.0445.8447.2452.9438.9466.9428.9321.5646.6538.5391.4

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:BalanceSheetLocation

us-gaap:DerivativeGainLossOnDerivativeNet

mgee:RegulatoryAsset


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value63000.0-708000.02932000.01481000.01550000.0-204000.0-1424000.0-638000.04000.0-375000.0-1028000.0-29000.0-73000.0687000.0948000.01450000.0482000.0441000.01094000.0304000.01800000.02118000.02135000.02278000.0847000.01289000.0733000.01184000.0-559000.06386000.0581000.0621000.0197000.0-1145000.0
Percentage of DerivativeGainLossOnDerivativeNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherCurrentAssets


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value19000.01039000.054000.0164000.0219000.01733000.0425000.0258000.0112000.0378000.0-843000.062000.042000.0645000.0393000.057000.068000.0166000.0101000.0-46000.0-21000.02004000.0817000.091000.044000.01794000.0265000.0249000.0-224000.01475000.0281000.0111000.0-11000.0-605000.0
Percentage of DerivativeGainLossOnDerivativeNet30.2-146.81.811.114.1-849.5-29.8-40.42800.0-100.882.0-213.8-57.593.941.53.914.137.69.2-15.1-1.294.638.34.05.2139.236.221.040.123.148.417.9-5.652.8

us-gaap:DerivativeGainLossOnDerivativeNet us-gaap:DerivativeInstrumentRisk, us-gaap:IncomeStatementLocation

mgee:FinancialTransmissionRights, mgee:FuelForElectricGenerationPurchasedPower


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value55000.0256000.015000.0-184000.041000.065000.071000.0429000.0-61000.0135000.077000.0150000.0300000.0175000.0115000.0224000.0439000.0685000.0-190000.0703000.0-136000.068000.0-298000.0233000.0255000.0119000.0181000.097000.0196000.0636000.0-1879000.0387000.0351000.0158000.0
Percentage of DerivativeGainLossOnDerivativeNet87.3-36.20.5-12.42.6-31.9-5.0-67.2-1525.0-36.0-7.5-517.2-411.025.512.115.491.1155.3-17.4231.2-7.63.2-14.010.230.19.224.78.2-35.110.0-323.462.3178.2-13.8

mgee:PurchasedPowerAgreement, mgee:FuelForElectricGenerationPurchasedPower


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-430000.0240000.0-2691000.0-753000.0-820000.0693000.01551000.0505000.0343000.0409000.0203000.0-328000.0-437000.0-518000.0-1027000.0-1351000.0-909000.0-761000.0-1070000.0-916000.0-1226000.0-1369000.0-1472000.0-1757000.0-570000.0-1021000.0-1054000.0-1068000.0-602000.01210000.07688000.0-1126000.0-1075000.0-1278000.0
Percentage of DerivativeGainLossOnDerivativeNet-682.5-33.9-91.8-50.8-52.9-339.7-108.9-79.28575.0-109.1-19.71131.0598.6-75.4-108.3-93.2-188.6-172.6-97.8-301.3-68.1-64.6-68.9-77.1-67.3-79.2-143.8-90.2107.718.91323.2-181.3-545.7111.6

us-gaap:CommodityContract, mgee:CostOfGasSoldExpense


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-33000.0-1022000.0-47000.0-28000.0-47000.0-1607000.0-403000.0-83000.0-99000.0-277000.0836000.00-22000.0-615000.0-407000.0-18000.0-63000.0-146000.0-250000.000-1814000.0-806000.017000.02000.0-1761000.0-264000.018000.0128000.01220000.01476000.000-608000.0
Percentage of DerivativeGainLossOnDerivativeNet-52.4144.4-1.6-1.9-3.0787.728.313.0-2475.073.9-81.3-0.030.1-89.5-42.9-1.2-13.1-33.1-22.90.00.0-85.6-37.80.70.2-136.6-36.01.5-22.919.1254.00.00.053.1

us-gaap:CommodityContract, mgee:FuelForElectricGenerationPurchasedPower


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value326000.0195000.0-263000.0-680000.0-943000.0-680000.0-220000.0-471000.0-299000.0-270000.0755000.0145000.0190000.0-374000.0-22000.0-362000.0-17000.0-385000.0315000.0-45000.0-417000.0-1007000.0-376000.0-862000.0-578000.0-420000.0139000.0-480000.01061000.04795000.0-1087000.07000.0538000.0-22000.0
Percentage of DerivativeGainLossOnDerivativeNet517.5-27.5-9.0-45.9-60.8333.315.473.8-7475.072.0-73.4-500.0-260.3-54.4-2.3-25.0-3.5-87.328.8-14.8-23.2-47.5-17.6-37.8-68.2-32.619.0-40.5-189.875.1-187.11.1273.11.9

us-gaap:DerivativeNonmonetaryNotionalAmountEnergyMeasure us-gaap:DerivativeInstrumentRisk

us-gaap:DerivativeNonmonetaryNotionalAmountEnergyMeasure

us-gaap:CommodityContract


Derivative
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-31
Value7720.0277400.0-71320.0-82920.0-85640.0498960.0-48920.0-40960.067280.0440440.0-96010.0-43120.0-12480.0538050.0-82295.0173440.046000.0415160.0-72440.0-13890.011135.0468590.012020.0-31260.0-34100.0408920.0430.016060.021710.0409800.0
Percentage of DerivativeNonmonetaryNotionalAmountEnergyMeasure100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash

us-gaap:DividendsCommonStockCash


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1313131312121212111111111111111110101010101010109.7959.7949.7959.7949.429.429.4229.4219.1329.1329.1319.1338.8448.8438.8438.84326-8.67-8.515
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:DividendsCommonStockCash us-gaap:StatementEquityComponents

us-gaap:RetainedEarnings


Dividends
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1313131312121212111111111111111110101010101010109.7959.7949.7959.7949.429.429.4229.4219.1329.1329.1319.1338.8448.8438.8438.84326-8.67-8.515
Percentage of DividendsCommonStockCash100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value21.021.021.00.210.2100.210.210.2100.210.210.2100.350.350.35
Percentage of EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value21.021.021.00.210.2100.210.210.2100.210.210.2100.350.350.35
Percentage of EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate

us-gaap:EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value14.516.72.00.0260.0260.0020.0190.0240.02400.0180.0190.0180.181000
Percentage of EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.00.00.00.0

us-gaap:EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value15.918.32.20.0270.0280.0030.0210.0260.02600.0180.0190.020.19300.0010
Percentage of EffectiveIncomeTaxRateReconciliationChangeInEnactedTaxRate109.7109.6110.0103.8107.7150.0110.5108.3108.30.0100.0100.0111.1106.60.00.00.0

us-gaap:EffectiveIncomeTaxRateReconciliationDeductionsOther

us-gaap:EffectiveIncomeTaxRateReconciliationDeductionsOther


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.50.61.10.0140.01600.0040.0020.002-0.0020.0060.0110.00400.0010.0030.002
Percentage of EffectiveIncomeTaxRateReconciliationDeductionsOther100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationDeductionsOther dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.70.61.20.0150.01700.0040.0020.002-0.0030.0060.0110.00400.0010.0030.002
Percentage of EffectiveIncomeTaxRateReconciliationDeductionsOther113.3100.0109.1107.1106.30.0100.0100.0100.0150.0100.0100.0100.00.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent

us-gaap:EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent


Effective
Period End2021-06-302020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.1-0.40.00100-0.0050-0.005-0.0010-0.0030.0040.0010.0030.0020.002
Percentage of EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent100.0100.0100.00.00.0100.00.0100.0100.00.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value0.1-0.1-0.40.0010.0010-0.0050.001-0.005-0.001-0.001-0.0020.0060.0030.0040.0020.002
Percentage of EffectiveIncomeTaxRateReconciliationOtherReconcilingItemsPercent100.00.0100.0100.00.00.0100.00.0100.0100.00.066.7150.0300.0133.3100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.26.36.30.0630.063-0.0010.0630.0630.06300.0630.0630.064-0.0010.0520.0520.053
Percentage of EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.26.36.20.0620.063-0.0010.0620.0620.06200.0620.0620.0600.0510.0510.051
Percentage of EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes100.0100.098.498.4100.0100.098.498.498.40.098.498.493.8-0.098.198.196.2

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.31.60.10.0010.00100.0010.0010.00100.0010.0010.001-0.0030.0030.0030.001
Percentage of EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment100.0100.0100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1.51.80.10.0010.00100.0010.0010.00100.0010.0010.001-0.0040.0040.0040.001
Percentage of EffectiveIncomeTaxRateReconciliationTaxCreditsInvestment115.4112.5100.0100.0100.00.0100.0100.0100.00.0100.0100.0100.0133.3133.3133.3100.0

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsOther

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsOther


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.37.15.00.0670.0690.0010.0480.0620.05900.0030.0040.0050.0030.0110.0150.018
Percentage of EffectiveIncomeTaxRateReconciliationTaxCreditsOther100.0100.0100.0100.0100.0100.0100.0100.0100.00.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EffectiveIncomeTaxRateReconciliationTaxCreditsOther dei:LegalEntity

mgee:Mge


Effective
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value6.87.85.40.0730.0750.0010.0520.0680.0650.0010.0020.0040.0050.0030.0110.0160.02
Percentage of EffectiveIncomeTaxRateReconciliationTaxCreditsOther107.9109.9108.0109.0108.7100.0108.3109.7110.20.066.7100.0100.0100.0100.0106.7111.1

us-gaap:EquityMethodInvestmentDividendsOrDistributions

us-gaap:EquityMethodInvestmentDividendsOrDistributions


Equity
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1933000.01967000.02069000.02348000.01880000.02700000.01821000.01781000.01733000.02012000.01622000.01581000.02959000.02348000.02661000.02070000.02000000.02072000.03712000.01486000.01863000.0865000.01913000.01841000.01471000.01420000.01978000.01927000.01918000.01917000.01906000.01860000.01831000.01807000.01846000.01806000.01754000.01740000.01716000.01685000.01645000.01682000.01693000.0
Percentage of EquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:EquityMethodInvestmentDividendsOrDistributions dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:MgeTransco, mgee:ATCequitymethodinvesteemember


Equity
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value1933000.01967000.02349000.01880000.02391000.01781000.01733000.02012000.01581000.02959000.002070000.02000000.001486000.01863000.0865000.01841000.0
Percentage of EquityMethodInvestmentDividendsOrDistributions100.0100.0100.0100.088.6100.0100.0100.0100.0100.00.0100.0100.00.0100.0100.0100.0100.0

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value98000.0-307000.0-11126000.01524000.0-1710000.01453000.0-5693000.0492000.0-792000.0-644000.0566000.026000.082000.0-542000.0-1104000.0-1478000.0-550000.0-586000.0-1097000.0-278000.0-1809000.0-2163000.0-2138000.0-2285000.0
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings us-gaap:IncomeStatementLocation

mgee:CostOfGasSoldExpense


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value33000.0395000.0-207000.0-28000.0-47000.0269000.0-161000.0-83000.0-99000.0-88000.0-426000.0022000.0181000.0-167000.0-18000.0-63000.0-155000.0-85000.000010000.017000.0
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings33.7-128.71.9-1.82.718.52.8-16.912.513.7-75.30.026.8-33.415.11.211.526.57.7-0.0-0.0-0.0-0.5-0.7

mgee:PurchasedPowerExpense


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value65000.0-702000.0-1545000.0-1496000.0-1663000.01184000.0-1676000.0-409000.0-693000.0-556000.0992000.026000.060000.0-723000.0-937000.0-1460000.0-487000.0-431000.0-1012000.0-278000.0-1809000.0-2163000.0-2148000.0-2302000.0
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings66.3228.713.9-98.297.381.529.4-83.187.586.3175.3100.073.2133.484.998.888.573.592.3100.0100.0100.0100.5100.7

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value6.3775.8846.3955.5055.3175.0156.1475.2055.8585.7656.0415.7366.0325.8345.76.2996.1865.9966.5955.8145.6365.3015.5556.364
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements

us-gaap:FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements


Fair
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-30
Value6.0996.5464.6583.9443.2963.814.4374.7174.695.2947.0575.7375.8165.1194.6984.8075.4135.5365.3555.5373.8273.1383.4164.079
Percentage of FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromEquityMethodInvestments

us-gaap:IncomeLossFromEquityMethodInvestments


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value2.4642.4442.4412.3753.1392.2663.012.3642.2972.2182.7081.6721.992.4512.6932.3382.4862.6082.4052.0231.7672.2331.162.3982.2891.8811.8442.4232.4022.4812.3892.342.3092.3962.3152.282.2422.2422.1812.1672.172.0972.186
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromEquityMethodInvestments dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:MgeTransco, mgee:ATCequitymethodinvesteemember


Income
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value2.4132.422.3193.1392.2662.3642.2972.2181.6721.992.4512.3382.4862.6082.0231.7672.2332.398
Percentage of IncomeLossFromEquityMethodInvestments97.999.097.6100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncomeLossFromEquityMethodInvestments us-gaap:ConsolidationItems

us-gaap:OperatingSegments


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2.4642.4442.4412.3533.1412.2862.7392.3722.2672.168
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.099.1100.1100.991.0100.398.797.7

us-gaap:IncomeLossFromEquityMethodInvestments us-gaap:ConsolidationItems, us-gaap:StatementBusinessSegments

us-gaap:OperatingSegments, mgee:TransmissionInvestment


Income
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value2.4642.4442.4412.3533.1412.2862.7392.3722.2672.168
Percentage of IncomeLossFromEquityMethodInvestments100.0100.0100.099.1100.1100.991.0100.398.797.7

us-gaap:IncreaseDecreaseInOtherCurrentAssets

us-gaap:IncreaseDecreaseInOtherCurrentAssets


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value2.1482.8516.5514.444.155-14.089141.042-1.684-13.665253.59-3.912-25.208193.1266.904-28.19133-6.155-5.274-22.31138-9.435-11.614-17.985194.031-14.066-3.283132.297-0.009-17.341
Percentage of IncreaseDecreaseInOtherCurrentAssets100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherCurrentAssets dei:LegalEntity

mgee:Mge


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value9.1333.0374.5094.1085.493-12.953141.609-2.108-13.737243.822-3.907-24.779182.8586.839-27.23331-4.929-5.575-22.053
Percentage of IncreaseDecreaseInOtherCurrentAssets425.2106.568.892.5132.291.998.7154.4125.2100.597.3106.599.998.396.891.499.196.696.480.1105.798.8

us-gaap:IncreaseDecreaseInOtherCurrentLiabilities

us-gaap:IncreaseDecreaseInOtherCurrentLiabilities


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value-11.282-4.2133.173-0.613-5.457-2.73813-23.137-4.1333.1825.9317.3596.438-7.77121-6.099-2.198-9.3181.409-15.377101.48717-3.442-3.698-11.0913.32-1.675-25.44419110.021-0.927-4.59
Percentage of IncreaseDecreaseInOtherCurrentLiabilities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherCurrentLiabilities dei:LegalEntity

mgee:Mge


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-9.836-4.0370.303-0.773-4.7290.2912-23.33-4.4365.532-0.2567.9987.692-5.74918-5.649-1.999-9.022-0.354-13.906101.524
Percentage of IncreaseDecreaseInOtherCurrentLiabilities87.295.89.5126.186.7-10.691.3100.8107.3173.9-4.3108.7119.574.086.392.690.996.8-25.190.498.7102.5

us-gaap:IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet

us-gaap:IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-4274000.01115000.0863000.0-2801000.0-2978000.0-47000.03418000.0150000.0-2806000.03416000.04289000.01859000.0-2805000.0419000.0-6437000.0586000.0-1731000.0-1526000.0-51000.0-1328000.0-379000.0-937000.08230000.0-3060000.0-4378000.0-5935000.04570000.0-347000.0776000.0-547000.0-3686000.0-4592000.0-3644000.01077000.02526000.0-6366000.0-3898000.0746000.05175000.0-2244000.02080000.0-1135000.0
Percentage of IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet dei:LegalEntity

mgee:Mge


Increase
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-4033000.01380000.01110000.0-2678000.0-2840000.0428000.03398000.0439000.0-3188000.03629000.04320000.01919000.0-2761000.0468000.0-6399000.0662000.0-1653000.0-1488000.0-25000.0-1232000.0-334000.0-906000.0
Percentage of IncreaseDecreaseInOtherNoncurrentAssetsAndLiabilitiesNet94.4123.8128.695.695.4-910.699.4292.7113.6106.2100.7103.298.4111.799.4113.095.597.549.092.888.196.7

us-gaap:OtherNoncashIncomeExpense

us-gaap:OtherNoncashIncomeExpense


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-31
Value-4271000.0277000.03132000.0-1388000.0-968000.01974000.0935000.0-1409000.0749000.0-32000.0845000.0129000.0-312000.0152000.0323000.0-291000.0-171000.0-609000.0-733000.0-301000.0-306000.0-86000.0-875000.0-618000.0114000.0658000.0-1572000.0-234000.0398000.0679000.0133000.0297000.0203000.0-750000.0148000.0-530000.0-442000.0-660000.0-684000.0-319000.0-547000.0-178000.0
Percentage of OtherNoncashIncomeExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:OtherNoncashIncomeExpense dei:LegalEntity

mgee:Mge


Other
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-5144000.0252000.03062000.0-1614000.0-1341000.01721000.0803000.0-1834000.0785000.0-604000.0875000.0-61000.0-724000.017000.0-171000.0-373000.0-313000.0-658000.0-898000.0-286000.0-658000.0-112000.0
Percentage of OtherNoncashIncomeExpense120.491.097.8116.3138.587.285.9130.2104.81887.5103.6-47.3232.111.2-52.9128.2183.0108.0122.595.0215.0130.2

us-gaap:PaymentsForProceedsFromOtherInvestingActivities

us-gaap:PaymentsForProceedsFromOtherInvestingActivities


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-418000.0419000.0374000.0399000.0501000.0398000.0260000.092000.0-50000.0206000.0573000.0230000.0-633000.035000.0-396000.01142000.0-237000.0-541000.0-101000.0126000.01000.0183000.0145000.033000.04000.048000.032000.0142000.0441000.0682000.0425000.0322000.0179000.0279000.0408000.0-49000.0447000.0-109000.0-1793000.0-170000.0-362000.0452000.052000.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsForProceedsFromOtherInvestingActivities dei:LegalEntity

mgee:Mge


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
Value493000.0462000.0610000.0622000.0484000.0406000.0305000.0206000.043000.0228000.0425000.0258000.0224000.0198000.0-322000.0561000.0-220000.0229000.0-145000.09000.0455000.072000.0
Percentage of PaymentsForProceedsFromOtherInvestingActivities-117.9110.3163.1155.996.6102.0117.3223.9-86.0110.774.2112.2-35.4565.781.349.192.8-42.3143.67.145500.039.3

us-gaap:PaymentsToAcquireInterestInSubsidiariesAndAffiliates

us-gaap:PaymentsToAcquireInterestInSubsidiariesAndAffiliates


Payments
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1.670.671.5941.430.3551.6431.9190.8881.0650.741.1250.5331.0651.8774.2180.710.8882.9390.9220.8880.1770.6710.2680.1770.1770.280.3550.6050.5320.6930.3550.3550.5770.3730.4311.050.5830.3550.050.2670.2660.4250.532
Percentage of PaymentsToAcquireInterestInSubsidiariesAndAffiliates100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PaymentsToAcquireInterestInSubsidiariesAndAffiliates dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName

mgee:MgeTransco, mgee:ATCequitymethodinvesteemember


Payments
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value0.3590.3550.1780.8881.0650.1780.5331.0650.710.710.8881.420.8880.1770.5330.177
Percentage of PaymentsToAcquireInterestInSubsidiariesAndAffiliates25.1100.010.8100.0100.024.1100.0100.037.8100.0100.048.3100.0100.079.4100.0

us-gaap:PaymentsToAcquireInterestInSubsidiariesAndAffiliates dei:LegalEntity, us-gaap:ScheduleOfEquityMethodInvestmentEquityMethodInvesteeName, us-gaap:SubsequentEventType

mgee:MgeTransco, mgee:ATCequitymethodinvesteemember, us-gaap:SubsequentEvent


Payments
Period End2020-10-312020-07-312020-04-302019-10-312019-07-312019-04-302018-10-312018-07-312018-04-30
Value0.40.40.40.90.91.10.50.51.1
Percentage of PaymentsToAcquireInterestInSubsidiariesAndAffiliates0.00.00.00.00.00.00.00.00.0

us-gaap:PensionAndOtherPostretirementBenefitContributions

us-gaap:PensionAndOtherPostretirementBenefitContributions


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value1.5351.5521.721.6331.4731.472.0071.3881.3620.9571.6171.3271.3211.3191.5871.4331.1167.1681.3181.0380.937111.2160.8340.817100.8720.8160.8150.8180.8462.4120.743304.5212.7430.804201.1862.5520.744198.733
Percentage of PensionAndOtherPostretirementBenefitContributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionAndOtherPostretirementBenefitContributions dei:LegalEntity

mgee:Mge


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value1.5351.5521.721.6331.4731.472.0071.3881.3620.9571.6171.3271.3211.3191.5871.4331.1167.1681.3181.0380.93711
Percentage of PensionAndOtherPostretirementBenefitContributions100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionAndOtherPostretirementBenefitExpense

us-gaap:PensionAndOtherPostretirementBenefitExpense


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-1.1421.461-0.903-0.938-0.935-0.94-0.947-0.946-2.3940.474-0.458-0.468-0.515-0.5610.0530.0510.5250.2020.130.1350.087-0.0570.8330.840.8680.792-0.266-0.259-0.223-0.3323.3953.353.2223.3364.5384.5934.544.6823.4443.4413.4243.3943.149
Percentage of PensionAndOtherPostretirementBenefitExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:PensionAndOtherPostretirementBenefitExpense dei:LegalEntity

mgee:Mge


Pension
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-1.1421.461-0.903-0.938-0.935-0.94-0.947-0.946-2.3940.474-0.458-0.468-0.515-0.5610.0530.0510.5250.2020.130.1350.087-0.057
Percentage of PensionAndOtherPostretirementBenefitExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProceedsFromContributionsFromParent dei:LegalEntity

us-gaap:ProceedsFromContributionsFromParent

mgee:Mge


Proceeds
Period End2020-12-312020-09-302020-06-30
Value0.00.030
Percentage of ProceedsFromContributionsFromParent0.00.0100.0

us-gaap:ProceedsFromContributionsFromParent dei:LegalEntity, us-gaap:StatementEquityComponents

mgee:Mge, us-gaap:AdditionalPaidInCapital


Proceeds
Period End2020-12-312020-09-302020-06-30
Value0.00.030
Percentage of ProceedsFromContributionsFromParent0.00.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock

us-gaap:ProceedsFromIssuanceOfCommonStock


Proceeds
Period End2020-12-312020-09-302020-06-30
Value0.00.079
Percentage of ProceedsFromIssuanceOfCommonStock0.00.0100.0

us-gaap:ProceedsFromIssuanceOfCommonStock us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Proceeds
Period End2020-12-312020-09-302020-06-30
Value0.00.078
Percentage of ProceedsFromIssuanceOfCommonStock0.00.098.1

us-gaap:CommonStock


Proceeds
Period End2020-12-312020-09-302020-06-30
Value0.00.01.495
Percentage of ProceedsFromIssuanceOfCommonStock0.00.01.9

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value-815000.0-523000.0-378000.0-145000.0-366000.0-664000.0-507000.0-138000.0-194000.0-999000.0-3000.0-659000.000-231000.0-49000.0-28000.0-289000.0-5000.0-25000.0-40000.000-531000.0-487000.000-50000.00-80000.0-5000.0-755000.0-10000.000-29000.0-796000.0-19000.00-37000.012000.0-311000.00
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.0100.0100.0100.0100.0100.00.00.0100.0100.00.00.0100.00.0100.0100.0100.0100.00.00.0100.0100.0100.00.0100.0100.0100.00.0

us-gaap:ProceedsFromPaymentsForOtherFinancingActivities dei:LegalEntity

mgee:Mge


Proceeds
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value-815000.0-523000.0-379000.0-145000.0-335000.0-664000.0-507000.0-95000.0-194000.0-844000.0-3000.0-659000.000-224000.0-10000.0-16000.0-289000.0-16000.0-18000.0-29000.00
Percentage of ProceedsFromPaymentsForOtherFinancingActivities100.0100.0100.3100.091.5100.0100.068.8100.084.5100.0100.00.00.097.020.457.1100.0320.072.072.50.0

us-gaap:ProvisionForDoubtfulAccounts

us-gaap:ProvisionForDoubtfulAccounts


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value387000.0388000.0337000.0261000.083000.0734000.0637000.0246000.098000.0634000.0724000.0288000.090000.0264000.0366000.0283000.0113000.0254000.0613000.0100000.0-109000.0592000.0674000.0-163000.0-12000.097000.0897000.017000.0241000.0743000.0897000.0467000.0341000.0743000.0961000.0330000.040000.01167000.0871000.0428000.0-25000.01038000.0848000.0
Percentage of ProvisionForDoubtfulAccounts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ProvisionForDoubtfulAccounts dei:LegalEntity

mgee:Mge


Provision
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value387000.0388000.0337000.0261000.083000.0734000.0637000.0246000.098000.0634000.0724000.0288000.090000.0264000.0366000.0283000.0113000.0254000.0613000.0100000.0-109000.0592000.0
Percentage of ProvisionForDoubtfulAccounts100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

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

us-gaap:PublicUtilitiesApprovedEquityCapitalStructurePercentage

mgee:Mge, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-55.53955.53900.5610000.566
Percentage of PublicUtilitiesApprovedEquityCapitalStructurePercentage100.0100.00.0100.00.00.00.0100.0

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

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreaseAmount

mgee:Mge, mgee:ElectricRateProceeding, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312017-12-312017-09-302017-06-302017-03-31
Value0.00.00.0-3.40.00.00.0-9.20.00.00.0-3.3
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount0.00.00.0100.00.00.00.0100.00.00.00.0100.0

mgee:Mge, mgee:GasRateProceeding, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312017-12-312017-09-302017-06-302017-03-31
Value0.00.00.02.40.00.00.01.70.00.00.03.1
Percentage of PublicUtilitiesApprovedRateIncreaseDecreaseAmount0.00.00.0-70.60.00.00.0-18.50.00.00.0-93.9

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

us-gaap:PublicUtilitiesApprovedRateIncreaseDecreasePercentage

mgee:Mge, mgee:ElectricRateProceeding, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312017-12-312017-09-302017-06-302017-03-31
Value0.84-0.83160-0.0084000-0.0224000-0.008
Percentage of PublicUtilitiesApprovedRateIncreaseDecreasePercentage100.0100.00.0100.00.00.00.0100.00.00.00.0100.0

mgee:Mge, mgee:GasRateProceeding, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312017-12-312017-09-302017-06-302017-03-31
Value-1.44541.445400.01460000.01060000.019
Percentage of PublicUtilitiesApprovedRateIncreaseDecreasePercentage-172.1-173.80.0-173.80.00.00.0-47.30.00.00.0-237.5

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

us-gaap:PublicUtilitiesApprovedReturnOnEquityPercentage

mgee:Mge, mgee:PublicServiceCommissionOfWisconsin


Public
Period End2020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-31
Value-9.7029.70200.0980000.098
Percentage of PublicUtilitiesApprovedReturnOnEquityPercentage100.0100.00.0100.00.00.00.0100.0

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

us-gaap:PublicUtilitiesRequestedRateIncreaseDecreasePercentage

mgee:Mge, mgee:ElectricRateProceeding, mgee:PublicServiceCommissionOfWisconsin, us-gaap:SubsequentEvent


Public
Period End2020-07-13
Value0
Percentage of PublicUtilitiesRequestedRateIncreaseDecreasePercentage0.0

mgee:Mge, mgee:GasRateProceeding, mgee:PublicServiceCommissionOfWisconsin, us-gaap:SubsequentEvent


Public
Period End2020-07-13
Value0.04
Percentage of PublicUtilitiesRequestedRateIncreaseDecreasePercentage0.0

us-gaap:RegulatedOperatingRevenueElectricNonNuclear

us-gaap:RegulatedOperatingRevenueElectricNonNuclear


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value1021009011693939312097978811999949212010298
Percentage of RegulatedOperatingRevenueElectricNonNuclear100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedOperatingRevenueElectricNonNuclear dei:LegalEntity

mgee:Mge


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
Value10210090116939393120979788119999492120
Percentage of RegulatedOperatingRevenueElectricNonNuclear100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedOperatingRevenueGas

us-gaap:RegulatedOperatingRevenueGas


Regulated
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-31
Value286745182356471725705118246247182458
Percentage of RegulatedOperatingRevenueGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RegulatedOperatingRevenueGas dei:LegalEntity

mgee:Mge


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
Value28674518235647172570511824624718
Percentage of RegulatedOperatingRevenueGas100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty us-gaap:RelatedPartyTransactionsByRelatedParty

us-gaap:RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty

mgee:ATCequitymethodinvesteemember


Related
Period End2021-06-302021-03-312020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-30
Value8.08.07.77.67.77.67.67.67.27.27.27.37.39.27.47.49.77.0
Percentage of RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid us-gaap:PlanName

us-gaap:ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid

mgee:Performanceunitplananddirectorincentiveplan


Share
Period End2021-01-31
Value1900000.0
Percentage of ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsShareBasedLiabilitiesPaid100.0

us-gaap:StockIssuedDuringPeriodSharesNewIssues

us-gaap:StockIssuedDuringPeriodSharesNewIssues


Stock
Period End2020-09-302020-06-302020-03-312019-09-302019-06-302019-03-312018-09-302018-06-302018-03-312017-09-302017-06-302017-03-312016-09-302016-06-302016-03-312015-09-302015-06-302015-03-312014-09-302014-06-302014-03-312013-09-302013-06-302013-03-312012-09-302012-06-302012-03-312011-09-302011-06-302011-03-31
Value01500000.00000000000000000000000000000
Percentage of StockIssuedDuringPeriodSharesNewIssues0.0100.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.00.0

us-gaap:StockIssuedDuringPeriodSharesNewIssues us-gaap:StatementEquityComponents

us-gaap:CommonStock


Stock
Period End2020-09-302020-06-30
Value01495000.0
Percentage of StockIssuedDuringPeriodSharesNewIssues0.099.7

us-gaap:StockholdersEquityOther

us-gaap:StockholdersEquityOther


Stockholders
Period End2021-06-302021-03-31
Value120000.0158000.0
Percentage of StockholdersEquityOther100.0100.0

us-gaap:StockholdersEquityOther us-gaap:StatementEquityComponents

us-gaap:AdditionalPaidInCapital


Stockholders
Period End2021-06-302021-03-31
Value120000.0158000.0
Percentage of StockholdersEquityOther100.0100.0

us-gaap:UnrealizedGainLossOnDerivatives us-gaap:BalanceSheetLocation

us-gaap:UnrealizedGainLossOnDerivatives

mgee:RegulatoryAsset


Unrealized
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-30
Value8.0493.588-3.1374.6952.6480.6893.2374.56-3.2280.9225.1882.0074.027-0.128-0.9551.2771.7310.689-0.4470.6634.58-6.37-0.072-4.036-3.16-1.318-3.572-5.3299.817133.739-2.331.9631.6974.8110.468-9.791
Percentage of UnrealizedGainLossOnDerivatives100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpense

us-gaap:UtilitiesOperatingExpense


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
Value1071281179695118119991021371169710013111496991231149093117108949813811695104166129100103129117979212011397941331159388137
Percentage of UtilitiesOperatingExpense100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpense dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value10712811796951181189910213612110610413699110107133121104101126
Percentage of UtilitiesOperatingExpense99.899.999.899.899.799.899.899.999.799.8104.4109.1104.7104.087.7114.4107.5108.0106.0116.4108.8107.4

us-gaap:UtilitiesOperatingExpenseDepreciationAndAmortization

us-gaap:UtilitiesOperatingExpenseDepreciationAndAmortization


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value18181818181818181817141413131313131211111111111110101010109.7469.9749.719.539.6249.6659.7069.7129.624101010109.222
Percentage of UtilitiesOperatingExpenseDepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseDepreciationAndAmortization dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value18181818181818181817141413131313131211111111
Percentage of UtilitiesOperatingExpenseDepreciationAndAmortization100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.099.999.9

us-gaap:UtilitiesOperatingExpenseFuelUsed

us-gaap:UtilitiesOperatingExpenseFuelUsed


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-31
Value101310128.6929.70611151013121615111315111213201512121712116.9929.838111411139.8110
Percentage of UtilitiesOperatingExpenseFuelUsed100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseFuelUsed dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value101310128.6929.70611151013121615111315111213201512
Percentage of UtilitiesOperatingExpenseFuelUsed100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value50455045464449484846454443444541434244404042433841404337404046414141464141424639403941
Percentage of UtilitiesOperatingExpenseMaintenanceAndOperations100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseMaintenanceAndOperations dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value50454945454449474846454343444541434243404042
Percentage of UtilitiesOperatingExpenseMaintenanceAndOperations99.599.799.699.599.399.599.699.799.499.499.499.799.099.599.599.599.599.199.699.699.499.2

us-gaap:UtilitiesOperatingExpensePurchasedPower

us-gaap:UtilitiesOperatingExpensePurchasedPower


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value109.35510101010109.12611107.77113121710151615179.1671414181821221421181819212118181817191418141721
Percentage of UtilitiesOperatingExpensePurchasedPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpensePurchasedPower dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value109.35510101010109.12611107.77113121710151615179.1711414
Percentage of UtilitiesOperatingExpensePurchasedPower100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseTaxes

us-gaap:UtilitiesOperatingExpenseTaxes


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-312015-12-312015-09-302015-06-302015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-302011-03-312010-03-31
Value5.0254.8274.8625.014.9754.9074.8325.0784.9854.9634.7574.874.9144.8694.7854.734.8524.9275.2214.8464.9675.0284.9284.8774.995.0844.7914.8725.1284.8614.5584.6054.7654.6794.4234.3834.5545.04.2914.3474.0054.7014.564
Percentage of UtilitiesOperatingExpenseTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

us-gaap:UtilitiesOperatingExpenseTaxes dei:LegalEntity

mgee:Mge


Utilities
Period End2021-06-302021-03-312020-12-312020-09-302020-06-302020-03-312019-12-312019-09-302019-06-302019-03-312018-12-312018-09-302018-06-302018-03-312017-12-312017-09-302017-06-302017-03-312016-12-312016-09-302016-06-302016-03-31
Value5.0254.8274.8585.014.9754.9074.8325.0784.9854.9634.7574.874.9144.8694.7854.734.8524.9275.2214.8464.9675.028
Percentage of UtilitiesOperatingExpenseTaxes100.0100.099.9100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

dei:EntityCommonStockSharesOutstanding

dei:EntityCommonStockSharesOutstanding


Entity
Period End2020-07-312020-04-302020-01-312019-10-312019-07-312019-04-302019-02-012018-10-312018-07-312018-04-302018-02-012017-10-312017-07-312017-04-302017-02-012016-10-312016-07-292016-04-302016-02-012015-10-312015-07-312015-03-312014-12-312014-09-302014-06-302014-03-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-09-302011-06-30
Value36343434343434343434343434343434343434343434343434343423232323232323232323
Percentage of EntityCommonStockSharesOutstanding100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:AccountsReceivableLatePaymentChargeOnUnpaidReceivablesSuspended

mgee:AccountsReceivableLatePaymentChargeOnUnpaidReceivablesSuspended


Accounts
Period End2020-12-31
Value1.0
Percentage of AccountsReceivableLatePaymentChargeOnUnpaidReceivablesSuspended100.0

mgee:AccruedInterestAndTaxes

mgee:AccruedInterestAndTaxes


Accrued
Period End2020-12-312019-12-312018-12-312017-12-312016-12-312015-12-312014-12-312013-12-312013-09-302013-06-302013-03-312012-12-312012-09-302012-06-302012-03-312011-12-312011-03-312010-12-312009-12-31
Value8.5397.2447.3845.6025.4955.0675.0865.6614.0414.1994.0994.2964.0644.1314.5424.0854.1773.994.028
Percentage of AccruedInterestAndTaxes100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0100.0

mgee:AccruedInterestAndTaxes dei:LegalEntity

mgee:Mge


Accrued</