v2.4.0.6

Fair Value Of Financial Assets And Liabilities (Narrative) (Details) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Mar. 31, 2013 | Mar. 31, 2012
Auction Rate Securities [Abstract] |  |
Settlements | $ 7 | $ (9)
Interest Rate Current [Member] |  |
Auction Rate Securities [Abstract] |  |
Level 3 ARS Assumptions | 0.30% |
Auction Rate Securities [Member] | Discounted Cash Flow [Member] | Risk Adjusted Discount Rates [Member] |  |
Auction Rate Securities [Abstract] |  |
Level 3 ARS Assumptions | 5.00% |
Duke Energy Carolinas [Member] |  |
Auction Rate Securities [Abstract] |  |
Settlements | 7 |
Duke Energy Ohio [Member] |  |
Auction Rate Securities [Abstract] |  |
Settlements | (3) |
Duke Energy Indiana [Member] |  |
Auction Rate Securities [Abstract] |  |
Settlements |  | $ (10)

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- Details
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- Definition Assumptions used in valuing Level 3 ARS investments + References No definition available. + Details
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Namespace Prefix: | duk_
Data Type: | num:percentItemType
Balance Type: | na
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- Definition Settlements that have taken place during the period in relation to assets measured at fair value and categorized within Level 3 of the fair value hierarchy. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258 + Details
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