Business Segments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Net Income (Loss)	$ 598	$ 470	$ 1,345	$ 1,424
Costs to Achieve Merger	293		306
Costs To Achieve Merger Tax	164		166
International Energy Interest In National Methanol [Member]
Equity ownership interest rate	25.00%		25.00%
Duke Energy Interest In DukeNet [Member]
Equity ownership interest rate	50.00%		50.00%
Exxon Mobil Interest In DETM [Member]
Equity ownership interest rate	40.00%		40.00%
Duke Energy Interest In DETM [Member]
Equity ownership interest rate	60.00%		60.00%
Edwardsport IGCC Plant [Member]
Asset Impairment Charges Edwardsport			600	222
Duke Energy Carolinas [Member]
Net Income (Loss)	258	311	735	709
Duke Energy Carolinas [Member] \| Other [Member]
Net Income (Loss)	119		137
Duke Energy Indiana [Member]
Net Income (Loss)	(19)	(31)	(109)	113
Duke Energy Indiana [Member] \| Other [Member]
Net Income (Loss)	$ 14		$ 19

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References+ Details

The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest.

+ References

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+ Details