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hedging instruments. 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Notional amount refers to the monetary amount specified in the interest rate derivative contract.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 false2Fair value hedges39false 5us-gaap_NotionalAmountOfInterestRateDerivativesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse2700000027USD$falsefalsefalse2truefalsefalse277000000277USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 true2Total notional amount40true 4duk_NotionalAmountOfDerivativesAtFairValueAbstractduk_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]41false 5duk_ElectricityEnergyGigawattHoursduk_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse6459964599[2]falsefalsefalse2truefalsefalse5121551215[2]falsefalsefalsexbrli:integerItemTypeintegerElectricity energy gigawatt hoursNo definition available.false256Electricity-energy (Gigawatt-hours)42false 5duk_NaturalGasDecathermsduk_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse197000000197000000falsefalsefalse2truefalsefalse180000000180000000falsefalsefalsexbrli:decimalItemTypedecimalAggregate notional amount of natural gas of derivatives not designated as a hedging instrument.No definition available.false256Natural gas (millions of decatherms)43false 0truefalsetruefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalse15false USDtruefalseFROM_Jan01_2013_TO_Jun30_2013_dei_LegalEntityAxis_DukeEnergyIndianaMemberhttp://www.sec.gov/CIK0001326160duration2013-01-01T00:00:002013-06-30T00:00:00falsefalseDuke Energy Indiana [Member]dei_LegalEntityAxisxbrldihttp://xbrl.org/2006/xbrldiduk_DukeEnergyIndianaMemberdei_LegalEntityAxisexplicitMemberGigawattHoursStandardhttp://www.duke-energy.com/20130630GWhduk0USDollarStandardhttp://www.xbrl.org/2003/iso4217USDiso42170$nanafalse0Duke Energy Indiana [Member]44true 4us-gaap_NotionalAmountOfDerivativesTotalAbstractus-gaap_truenadurationfalsefalsefalsefalsefalsefalsefalsefalse1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Notional Amounts Of Derivative Instruments Related To Interest Rate Risk [Abstract]45false 5us-gaap_NotionalAmountOfInterestRateDerivativeInstrumentsNotDesignatedAsHedgingInstrumentsus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse200000000200[3]USD$falsefalsefalse2truefalsefalse200000000200USD$falsefalsefalsexbrli:monetaryItemTypemonetaryAggregate notional amount of all interest rate derivatives not designated as hedging instruments. Notional amount refers to the monetary amount specified in the interest rate derivative contract.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 false2Undesignated contracts46false 5us-gaap_NotionalAmountOfInterestRateDerivativesus-gaap_truedebitinstantfalsefalsefalsefalsefalsefalsefalsefalsetotalLabel1truefalsefalse200000000200USD$falsetruefalse2truefalsefalse200000000200USD$falsetruefalsexbrli:monetaryItemTypemonetaryAggregate notional amount of interest rate derivatives, which relates to the currency amount specified in the interest rate derivative instruments.Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Notional Amount -URI http://asc.fasb.org/extlink&oid=6519104 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959 true2Total notional amount47true 4duk_NotionalAmountOfDerivativesAtFairValueAbstractduk_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1falsefalsefalse00falsefalsefalse2falsefalsefalse00falsefalsefalsexbrli:stringItemTypestringfalse0Underlying Notional Amounts For Derivative Instruments Accounted For At Fair Value [Abstract]48false 5duk_ElectricityEnergyGigawattHoursduk_falsenadurationfalsefalsefalsefalsefalsefalsefalsefalseterseLabel1truefalsefalse815815falsefalsefalse2truefalsefalse9797falsefalsefalsexbrli:integerItemTypeintegerElectricity energy gigawatt hoursNo definition available.false256Electricity-energy (Gigawatt-hours)1Duke Energy includes amounts related to non-recourse variable rate long-term debt of VIEs of $592 million and $620 million at June 30, 2013, and at December 31, 2012, respectively.2Amounts at Duke Energy Ohio included intercompany positions that were eliminated at Duke Energy.3In July 2013, $200 million of undesignated interest rate swaps at Duke Energy Indiana were terminated due to a new debt issuance. See Note 6 for more information.falseRisk Management, Derivative Instruments and Hedging Activities (Notional Amounts of Derivative Instruments) (Details) (USD $)MillionsUnKnownUnKnownUnKnowntruefalsefalseSheethttp://www.duke-energy.com/role/RiskManagementDerivativeInstrumentsAndHedgingActivitiesNotionalAmountsOfDerivativeInstrumentsDetails248