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Derivatives and Hedging (Gains and Losses Recognized on Undesignated Contracts) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings $ 54us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet $ (260)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
Pretax gains (losses) recognized as regulatory assets or liabilities (344)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability 29duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (340)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
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Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts (5)duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
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= duk_RegulatoryAssetMember
Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (2)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember		 27duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
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= duk_RegulatoryLiabilityMember
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts 3duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
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= duk_RegulatoryLiabilityMember		  
Revenue: Regulated electric [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts 1us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
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= duk_RevenueRegulatedElectricMember
Revenue: Nonregulated electric, natural gas and other [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts 17us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueNonRegulatedElectricNaturalGasAndOtherMember		 (397)us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueNonRegulatedElectricNaturalGasAndOtherMember
Fuel used in electric generation and purchased power - regulated [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts   7us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
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= duk_FuelUsedInElectricGenerationAndPurchasedPowerRegulatedMember
Fuel used in electric generation and purchased power - nonregulated [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts 37us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerNonRegulatedMember		 138us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerNonRegulatedMember
Interest expense [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - interest rate contracts (1)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InterestExpenseMember		 (4)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
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= us-gaap_InterestExpenseMember
Duke Energy Carolinas [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities (28)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember		  
Duke Energy Carolinas [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (28)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember		  
Progress Energy [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings (1)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember		  
Pretax gains (losses) recognized as regulatory assets or liabilities (315)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember		 2duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Progress Energy [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (314)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
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/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts (4)duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
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= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Progress Energy [Member] | Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts 3duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember		  
Progress Energy [Member] | Revenue: Regulated electric [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts   (3)us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueRegulatedElectricMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Progress Energy [Member] | Fuel used in electric generation and purchased power - regulated [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts   7us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerRegulatedMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Progress Energy [Member] | Interest expense [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - interest rate contracts (1)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InterestExpenseMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember		 (4)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InterestExpenseMember
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Duke Energy Progress [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings   1us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Pretax gains (losses) recognized as regulatory assets or liabilities (130)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember		 20duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Progress [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (127)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember		 17duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts (5)duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember		 3duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Progress [Member] | Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts 2duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember		  
Duke Energy Progress [Member] | Revenue: Regulated electric [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts   (3)us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueRegulatedElectricMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Progress [Member] | Fuel used in electric generation and purchased power - regulated [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts   7us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerRegulatedMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Progress [Member] | Interest expense [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - interest rate contracts   (3)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InterestExpenseMember
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Florida [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings (1)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember		 (1)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember
Pretax gains (losses) recognized as regulatory assets or liabilities (185)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember		 (18)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember
Duke Energy Florida [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (187)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember		 (19)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts 1duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember		 1duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember
Duke Energy Florida [Member] | Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts 1duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember		  
Duke Energy Florida [Member] | Interest expense [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - interest rate contracts (1)us-gaap_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= us-gaap_InterestExpenseMember
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/ us-gaap_IncomeStatementLocationAxis
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/ dei_LegalEntityAxis
= duk_DukeEnergyFloridaMember
Duke Energy Ohio [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings 50us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		 (311)us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
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Pretax gains (losses) recognized as regulatory assets or liabilities 1duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		 2duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Duke Energy Ohio [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - interest rate contracts (1)duk_GainLossOnInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetOrLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		  
Duke Energy Ohio [Member] | Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts 2duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		 2duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Duke Energy Ohio [Member] | Revenue: Nonregulated electric, natural gas and other [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts 13us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueNonRegulatedElectricNaturalGasAndOtherMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		 (449)us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueNonRegulatedElectricNaturalGasAndOtherMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Duke Energy Ohio [Member] | Fuel used in electric generation and purchased power - nonregulated [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts 37us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerNonRegulatedMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember		 138us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_FuelUsedInElectricGenerationAndPurchasedPowerNonRegulatedMember
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Duke Energy Indiana [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings 1us-gaap_DerivativeInstrumentsNotDesignatedAsHedgingInstrumentsGainLossNet
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember		  
Pretax gains (losses) recognized as regulatory assets or liabilities (2)duk_GainLossOnDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember		  
Duke Energy Indiana [Member] | Regulatory assets [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts 2duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryAssetMember
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember		  
Duke Energy Indiana [Member] | Regulatory liabilities [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized as regulatory assets or liabilities - commodity contracts (4)duk_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsRecordedtoRegulatoryAssetorLiability
/ us-gaap_BalanceSheetLocationAxis
= duk_RegulatoryLiabilityMember
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember		  
Duke Energy Indiana [Member] | Revenue: Regulated electric [Member]    
Derivative Instruments, Gain (Loss) [Line Items]    
Pretax gains (losses) recognized in earnings - commodity contracts $ 1us-gaap_GainLossOnPriceRiskDerivativeInstrumentsNotDesignatedAsHedgingInstruments
/ us-gaap_IncomeStatementLocationAxis
= duk_RevenueRegulatedElectricMember
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember