v2.4.0.8

Derivatives and Hedging (Interest Rate Risk) (Details) (Interest Rate Contracts [Member], USD $) In Millions, unless otherwise specified | Sep. 30, 2014 | Dec. 31, 2013
--- | --- | ---
Derivative [Line Items] |  |
Notional amount | $ 791 | $ 832
Cash Flow Hedging [Member] |  |
Derivative [Line Items] |  |
Notional amount | 764 | 798
Duke Energy Ohio [Member] |  |
Derivative [Line Items] |  |
Notional amount | 27 | 27
Duke Energy Ohio [Member] | Cash Flow Hedging [Member] |  |
Derivative [Line Items] |  |
Notional amount |  |
Not Designated as Hedging Instrument [Member] |  |
Derivative [Line Items] |  |
Notional amount | 27 | 34
Not Designated as Hedging Instrument [Member] | Duke Energy Ohio [Member] |  |
Derivative [Line Items] |  |
Notional amount | 27 | 27
Variable Interest Entity, Primary Beneficiary [Member] | Cash Flow Hedging [Member] |  |
Derivative [Line Items] |  |
Notional amount | $ 552 | $ 584

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- Definition Aggregate notional amount specified by the derivative(s). Expressed as an absolute value. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 13 -Sentence Column B + Details
Name: | invest_DerivativeNotionalAmount
Namespace Prefix: | invest_
Data Type: | xbrli:monetaryItemType
Balance Type: | na
Period Type: | instant

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- Details
Name: | us-gaap_DerivativeLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration