XML 186 R120.htm IDEA: XBRL DOCUMENT v2.4.1.9
Fair Value Measurements (Reconciliation of Assets and Liabilities Measured At Fair Value On A Recurring Basis Using Unobservable Inputs) (Details) (USD $)
In Millions, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Beginning balance $ 111us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue $ 13us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue $ 85us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Amounts Acquired in Progress Energy Merger     (30)duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetAcquisition
Total pretax gains (losses) included in earnings (7)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 (42)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 8us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1
Total pretax gains (losses) included in comprehensive income     13us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
Purchases 84us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases 30us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases 36us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Sales (58)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales (6)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales (2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
Issuances   (11)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues (15)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
Settlements (54)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements 16us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements (87)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Transfers in and/or out of level 3 74us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet 86us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet  
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 6us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3 86us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3  
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability 5duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet 3duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet 5duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
Ending balance 155us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue 111us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue 13us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance 13us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs (85)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs (39)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
Amounts Acquired in Progress Energy Merger     (30)duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisNetDerivativeAcquisition
Total pretax gains (losses) included in earnings (7)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings (42)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings 8us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
Purchases 50us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases 21us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases 22us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases
Issuances   (11)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues (15)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
Settlements (54)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements 25us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements (32)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability (9)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability (3)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability 1duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
Ending balance (1)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs 13us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs (85)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at end of period (14)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss    
Investments [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Beginning balance 98us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
98us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
124us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Total pretax gains (losses) included in comprehensive income     13us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Purchases 34us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
9us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
14us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Sales (58)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
(6)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
(2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Settlements   (9)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
(55)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Transfers in and/or out of level 3 68us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
   
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability 14duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
6duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
4duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Ending balance 156us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
98us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
98us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
Derivative [Member]      
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Pretax amounts included in the Consolidated Statements of Comprehensive Income related to Level 3 measurements outstanding at end of period (14)us-gaap_FairValueAssetsMeasuredOnRecurringBasisChangeInUnrealizedGainLoss
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_DerivativeMember
   
Duke Energy Carolinas [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Beginning balance 79us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
60us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
65us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Total pretax gains (losses) included in comprehensive income     2us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Purchases 34us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
9us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
14us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Sales (43)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
  (14)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Issuances   (6)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
(2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Settlements 2us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
10us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
(9)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Transfers in and/or out of level 3 68us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
   
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability 14duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
6duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
4duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Ending balance 154us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
79us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
60us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance (2)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
(12)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
 
Sales     (14)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSales
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Settlements 2us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
10us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
2us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Ending balance   (2)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
(12)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Duke Energy Carolinas [Member] | Investments [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Beginning balance 81us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
72us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
65us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Total pretax gains (losses) included in comprehensive income     2us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Purchases 34us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
9us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
14us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Sales (43)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
   
Issuances   (6)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
(2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Settlements     (11)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Transfers in and/or out of level 3 68us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
   
Total gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability 14duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
6duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
4duk_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisDeferredGainsOrLossesAsRegulatoryAssetsAndLiabilitiesNet
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Ending balance 154us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
81us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
72us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue
/ us-gaap_FairValueByAssetClassAxis
= us-gaap_InvestmentsMember
/ dei_LegalEntityAxis
= duk_DukeEnergyCarolinasMember
Progress Energy [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3   34us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
 
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance   (38)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
(24)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Total pretax gains (losses) included in earnings     1us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Issuances   (10)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
16us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Settlements     4us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability   (6)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
(3)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Ending balance     (38)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_ProgressEnergyMember
Duke Energy Progress [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3   34us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
 
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance   (38)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
(24)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Total pretax gains (losses) included in earnings     1us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Issuances   (10)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
16us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Settlements     4us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability   (6)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
(3)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Ending balance     (38)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyProgressMember
Duke Energy Ohio [Member]      
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]      
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Transfers out of Level 3 6us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
43us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationTransfersOutOfLevel3
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
 
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance (4)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(6)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(3)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Total pretax gains (losses) included in earnings (9)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(42)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(3)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Purchases 1us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
1us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
 
Settlements (13)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
  1us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability 1duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
  (1)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Ending balance (18)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(4)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
(6)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyOhioMember
Duke Energy Indiana [Member]      
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]      
Beginning balance 12us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
10us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
4us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
Total pretax gains (losses) included in earnings 3us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
8us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
36us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationGainLossIncludedInEarnings
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
Purchases 49us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
20us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationPurchases
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
 
Issuances     (22)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationIssues
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
Settlements (41)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
(30)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
(52)us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsReconciliationSettlements
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
Total Gains (losses) included on the Consolidated Balance Sheet as regulatory asset or liability (9)duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
4duk_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputsDeferredGainsOrLossesAsRegulatoryAssetOrLiability
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
 
Ending balance $ 14us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
$ 12us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember
$ 10us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisWithUnobservableInputs
/ dei_LegalEntityAxis
= duk_DukeEnergyIndianaMember