Acquisitions And Dispositions Of Businesses And Sales Of Other Assets (Details) (USD $) Share data in Millions, unless otherwise specified	0 Months Ended	1 Months Ended	12 Months Ended											1 Months Ended	12 Months Ended
	Sep. 02, 2011	Jun. 30, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Merger Agreement [Member]	Dec. 31, 2011 Progress Energy [Member]	Dec. 31, 2011 Duke Energy Corp [Member]		Dec. 31, 2010 Duke Energy Corp [Member]		Dec. 31, 2009 Duke Energy Corp [Member]		Dec. 31, 2010 DukeNet [Member]	Jun. 30, 2009 North Allegheny [Member]	Dec. 31, 2009 North Allegheny [Member] mW	Dec. 31, 2010 DukeNet and Alinda Capital Partners LLC [Member]	Dec. 31, 2011 Aguaytia [Member]
Conversion of Progress' common stock to Duke's common stock, per share, before reverse stock split adjustment					2.6125
Number of shares to be issued by Duke to acquire Progress, before reverse stock split adjustment			771
Adjusted conversion ratio, after reverse stock split adjustment			0.87083
Number of shares to be issued by Duke to acquire Progress, after reverse stock split adjustment					257
Value of transaction					$ 17,000,000,000
Incremental goodwill as a result of the merger					11,000,000,000
Debt assumed by Duke as a result of the merger					15,000,000,000
Settlement agreement, customer guaranteed savings	650,000,000
Merger agreement, termination fees						400,000,000	675,000,000
Transaction costs			68,000,000
Noncontrolling interest		24.00%
Payments to Acquire Additional Interest in Subsidiaries		28,000,000
Noncontrolling interest carrying amount		42,000,000
Equity increase result of transaction		14,000,000
Number of years under a fixed price purchased power agreement															23.5
MW of power generating assets															70
Payments for Purchase of Other Assets														124,000,000
Proceeds from Divestiture of Interest in Joint Venture				137,000,000
Pre-tax gain							$ 8,000,000	[1]	$ 153,000,000	[2]	$ 36,000,000	[3]	$ 139,000,000
Equity Method Investment, Ownership Percentage									50.00%				50.00%			50.00%	100.00%

[1] These gains primarily relate to sales of emission allowances by USFE&G and Commercial Power.

[2] These gains primarily relate to the DukeNet gain as discussed above and sales of emission allowances by USFE&G and Commercial Power. The loss at Duke Energy Indiana relates primarily to the retirement of certain software assets.

[3] These gains primarily relate to sales of emission allowances by USFE&G and Commercial Power. The loss at Duke Energy Indiana relates primarily to the sale of NOx.