2.2.0.7 true Variable Interest Entities (Narrative) (Details) (USD $) 41001 - Disclosure - Variable Interest Entities (Narrative) (Details) true false In Millions false false 1 USD false false Unit13 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Unit12 Standard http://www.xbrl.org/2003/instance pure xbrli 0 Unit1 Standard http://www.xbrl.org/2003/instance shares xbrli 0 Unit14 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 $ false 2 USD false false Unit13 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 Unit14 Divide http://www.xbrl.org/2003/iso4217 USD iso4217 http://www.xbrl.org/2003/instance shares xbrli 0 Unit1 Standard http://www.xbrl.org/2003/instance shares xbrli 0 $ false 3 USD true false false false DERF [Member] dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi duk_DerfMember dei_LegalEntityAxis explicitMember Unit13 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ false 4 USD true false false false Wind Assets [Member] dei_LegalEntityAxis xbrldi http://xbrl.org/2006/xbrldi duk_WindAssetsMember dei_LegalEntityAxis explicitMember Unit13 Standard http://www.xbrl.org/2003/iso4217 USD iso4217 0 $ 5 Subordinated retained interest limitation of the total proceeds 3 duk_SubordinatedRetainedInterestLimitationOfTotalProceeds duk false na duration Subordinated Retained Interest Limitation Of The Total Proceeds false false false false false false false false false false false verboselabel false 1 false true false false 0.25 0.25 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Subordinated Retained Interest Limitation Of The Total Proceeds No authoritative reference available. false 6 Receivables to maintain minimum equity balance 3 duk_ReceivablesToMaintainMinimumEquityBalance duk false debit instant Receivables To Maintain Minimum equity Balance false false false false false false false false false false false terselabel false 1 true true false false 3000000 3 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false xbrli:monetaryItemType monetary Receivables To Maintain Minimum equity Balance No authoritative reference available. false 7 Borrowing Limitation 3 duk_BorrowingLimitation duk false na duration Borrowing limitation. false false false false false false false false false false false label false 1 false true false false 0.75 0.75 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Borrowing limitation. No authoritative reference available. false 8 Restricted Receivables of VIE's, retained interest 3 duk_RestrictedReceivablesOfViesRetainedInterest duk false debit instant Restricted Receivables Of VIEs Retained Interest false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false true false false 340000000 340 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false xbrli:monetaryItemType monetary Restricted Receivables Of VIEs Retained Interest No authoritative reference available. false 9 Secured credit facility of VIE 3 duk_SecuredCreditFacilityOfVie duk false credit instant Secured Credit Facility Of Vie false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false true false false 300000000 300 true false false 4 false false false false 0 0 true false false xbrli:monetaryItemType monetary Secured Credit Facility Of Vie No authoritative reference available. false 10 Line of Credit Facility, Expiration Date 3 us-gaap_LineOfCreditFacilityExpirationDate us-gaap true na duration No definition available. false false false false false false false false false false false false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 August 2012 August 2012 true false false 4 false false false false 0 0 true false false us-types:dateStringItemType normalizedstring Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter). Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 false 11 Long-term loan agreement 3 duk_LongTermDebtAgreement duk false debit duration Long Term Loan Agreement Wind Farms false false false false false false false false false false false terselabel false 1 false false false false 0 0 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 true true false false 325000000 325 true false false xbrli:monetaryItemType monetary Long Term Loan Agreement Wind Farms No authoritative reference available. false 12 Proceeds received for sale of receivables, portion received as note payable 3 duk_ProceedsReceivedForSaleOfReceivablesPortionReceivedAsNotePayable duk false na instant Proceeds Received For Sale Of Receivables Portion Received As Note Payable false false false false false false false false false false false verboselabel false 1 false true false false 0.25 0.25 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Proceeds Received For Sale Of Receivables Portion Received As Note Payable No authoritative reference available. false 13 Effect on fair value assumption 3 duk_EffectOnFairValueAssumption duk false na instant Effect on fair value assumption false false false false false false false false false false false terselabel false 1 false true false false 0.1 0.1 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Effect on fair value assumption No authoritative reference available. false 14 Effect on fair value assumption 3 duk_EffectOnFairValueAssumption20 duk false na duration Effect on fair value assumption 20% false false false false false false false false false false false verboselabel false 1 false true false false 0.2 0.2 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Effect on fair value assumption 20% No authoritative reference available. false 15 Discount rate calculation premium over LIBOR 3 duk_DiscountRateCalculationPremiumOverLibor duk false na instant Discount rate calculation premium over LIBOR. false false false false false false false false false false false terselabel false 1 false true false false 0.0239 0.0239 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Discount rate calculation premium over LIBOR. No authoritative reference available. false 16 Ownership percentage in variable interest entity 3 us-gaap_VariableInterestEntityOwnershipPercentage us-gaap true na duration No definition available. false false false false false false false false false false false terselabel false 1 false true false false 0.09 0.09 false false false 2 false false false false 0 0 false false false 3 false false false false 0 0 true false false 4 false false false false 0 0 true false false us-types:percentItemType pure Percentage of the VIE's voting interest owned by the registrant. In general, a VIE is a corporation, partnership, trust, or any other legal structure used for business purposes that either (a) does not have equity investors with voting rights or (b) has equity investors that do not provide sufficient financial resources for the entity to support its activities. A VIE often holds financial assets, including loans or receivables, real estate or other property. A VIE may be essentially passive or it may engage in research and development or other activities on behalf of another company. No authoritative reference available. false 4 12 false Millions UnKnown UnKnown false true