Acquisitions And Dispositions Of Businesses And Sales Of Other Assets (Cash proceeds and related net pre-tax gains related to the Sales of Asset) (Details) (Duke Energy Corp [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Duke Energy Corp [Member]
Proceeds	$ 12		$ 160		$ 63
Net pre-tax gains	$ 8	[1]	$ 153	[2]	$ 36	[3]

[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.