Acquisitions and Sales of Other Assets (Narrative) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended				6 Months Ended	0 Months Ended	12 Months Ended		0 Months Ended		9 Months Ended	0 Months Ended	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2012	Sep. 30, 2013	Jul. 02, 2012	Dec. 31, 2012 Purchase Price Allocation Adjustments [Member]	Jun. 30, 2012 Sumitomo Corporation of America [Member]	Jan. 12, 2012 Wabash Valley Power Association [Member]	Dec. 31, 2012 Ibener [Member]	Apr. 30, 2013 Ibener [Member]	Oct. 04, 2013 DukeNet [Member] Scenario Forecast [Member]	Jan. 12, 2012 Duke Energy Ohio [Member]	Sep. 30, 2012 Duke Energy Ohio [Member]	Jan. 12, 2012 Duke Energy Indiana [Member]	Sep. 30, 2013 Duke Energy Indiana [Member]	Sep. 30, 2012 Duke Energy Indiana [Member]
Significant Acquisitions and Disposals [Line Items]
Adjusted conversion ratio, after reverse stock split adjustment				87.083%
Fair value of outstanding earned stock compensation awards				$ 62
Total estimated purchase price			18,071	18,071
Costs to achieve the merger	293	322
Transfer of Vermillion Generating Station											28	28	26	0	26
Proceeds from sale of interest in jointly owned utility plant							14				82		68
Sale of ownership interest in Vermillion Generating Station											75.00%
Equity ownership interest rate						50.00%	37.50%						62.50%
Construction and 12-year amortizing term loan facility						330
Proceeds from issuance of other long-term debt						319
Cash collateral returned									192
Cash paid								415
Property, plant and equipment			23,141		(138)			383
Intangibles								30
Deferred tax								57
Working capital			3,204					6
Goodwill			12,469		2			54
Proceeds from divestiture of interest in joint venture										210
Other long-term assets, excluding goodwill			$ 9,990		$ (4)