Acquisitions and Dispositions (Assets Held For Sale) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	$ (5)	$ 378	$ 29	$ (578)
Charge for settlement agreement			53
Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	(2)	413	23	(597)
Charge for settlement agreement			53
Midwest Generation Business [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues		620	543	1,233
(Loss) Gain on disposition	(5)	460	(42)	(847)
(Loss) Income before income taxes	(5)	623	62	(864)
Income tax (benefit) expense	(1)	218	29	(321)
(Loss) Income From Discontinued Operations, net of tax	(4)	405	33	(543)
Midwest Generation Business [Member] | Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues		536	412	853
(Loss) Gain on disposition	(4)	466	(48)	(878)
(Loss) Income before income taxes	(4)	647	48	(917)
Income tax (benefit) expense	(2)	234	25	(320)
Other Disposal Groups [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	$ (1)	$ (27)	(4)	$ (35)
Antitrust Lawsuit [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Charge for settlement agreement			81
Antitrust Lawsuit [Member] | Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Charge for settlement agreement			$ 81