Goodwill and Other Intangible Assets (Intangible Assets) (Details) - USD ($) $ in Millions		Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance		$ 243	$ 362
Accumulated Amortization		(97)	(158)
Net Balance		146	204
Indefinite-Lived Intangible Assets (Excluding Goodwill)		68	77
Intangible Assets, Gross		311	439
Intangible Assets, Net		214	281
Land Use Rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		38	37
Water rights
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		17	20
Other
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)		13	20
Project development rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	[1]	4	28
Accumulated Amortization	[1]	(1)	(1)
Net Balance	[1]	3	27
Sales concessions
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance		71	86
Accumulated Amortization		(19)	(41)
Net Balance		52	45
Contractual payment rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	[2]	66	69
Accumulated Amortization	[2]	(46)	(40)
Net Balance	[2]	20	29
Management rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance		24	33
Accumulated Amortization		(10)	(13)
Net Balance		14	20
Land Use Rights [Member]
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance		28	25
Accumulated Amortization		0	0
Net Balance		28	25
Contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance		29	36
Accumulated Amortization		(12)	(19)
Net Balance		17	17
Customer relationships & contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	[3]	6	63
Accumulated Amortization	[3]	(6)	(39)
Net Balance	[3]	0	24
All other
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	[4]	15	22
Accumulated Amortization	[4]	(3)	(5)
Net Balance	[4]	$ 12	$ 17

[1] (1) 2014 balance includes U.K. Wind operations. In August 2014 these assets were sold, but did not meet the criteria to be reported as discontinued operations and their results are reflected within continuing operations. See Note 24—Dispositions and Held-for-Sale Businesses for further information.

[2] (2) Represent legal rights to receive system reliability payments from the regulator.

[3] (3) 2014 balance includes DPLER which is considered held-for-sale as of December 31, 2015. See Note 24—Dispositions and Held-for-Sale Businesses for further information.

[4] (4) Includes renewable energy certificates, emission allowances and various other intangible assets none of which is individually significant.