Acquisitions and Dispositions (Assets Held For Sale) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	$ (57)	$ (113)	$ 34	$ (956)
Charge for agreement in principle	46		53
Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	(65)	(135)	25	(1,010)
Charge for agreement in principle	46		53
Midwest Generation Business [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues		245	543	613
Gain (Loss) on disposition	6	(20)	(37)	(1,307)
(Loss) Income before income taxes	(80)	(184)	67	(1,487)
Income tax (benefit) expense	(21)	(73)	30	(539)
(Loss) Income From Discontinued Operations, net of tax	(59)	(111)	37	(948)
Midwest Generation Business [Member] | Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Operating Revenues		122	412	317
Gain (Loss) on disposition		(21)	(44)	(1,344)
(Loss) Income before income taxes	(88)	(210)	52	(1,564)
Income tax (benefit) expense	(23)	(75)	27	(554)
Other Disposal Groups [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
(Loss) Income From Discontinued Operations, net of tax	2	$ (2)	(3)	$ (8)
Antitrust Lawsuit [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Charge for agreement in principle	71		81
Antitrust Lawsuit [Member] | Duke Energy Ohio [Member]
Disposal Group, Including Discontinued Operation, Income Statement Disclosures [Abstract]
Charge for agreement in principle	$ 71		$ 81