v2.4.0.8

Derivatives and Hedging (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 9 Months Ended
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Sep. 30, 2014
Derivative [Line Items] |
Undesignated commodity contracts latest expiration year | 2018
Interest rate cash flow hedge gain (loss) to be reclassified during next 12 months, net | $ 9

X
- Definition Latest year for which outstanding undesignated contracts used to hedge commodity price risk expire + References No definition available. + Details
Name: | duk_UndesignatedCommodityContractsLatestExpirationYear
Namespace Prefix: | duk_
Data Type: | xbrli:gYearItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 30 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=35736893&loc=d3e80748-113994 + Details
Name: | us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant