Goodwill and Other Intangible Assets (Intangible Assets) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2013		Dec. 31, 2012
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	$ 370		$ 467
Accumulated Amortization	(153)		(222)
Net Balance	217		245
Indefinite-Lived Intangible Assets (Excluding Goodwill)	80		79
Intangible Assets, Gross	450		546
Intangible Assets, Net	297		324
Land use rights
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	46		50
Water rights
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	20		18
Trademark/Trade name
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	5		6
Other
Finite-Lived Intangible Assets, Net [Abstract]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	9		5
Project development rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	31	[1]	32	[1]
Accumulated Amortization	(1)	[1]	(1)	[1]
Net Balance	30	[1]	31	[1]
Sales concessions
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	95	[2]	108	[2]
Accumulated Amortization	(45)	[2]	(49)	[2]
Net Balance	50	[2]	59	[2]
Contractual payment rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	74	[3]	72	[3]
Accumulated Amortization	(33)	[3]	(23)	[3]
Net Balance	41	[3]	49	[3]
Management rights
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	37		40
Accumulated Amortization	(13)		(14)
Net Balance	24		26
Emission allowances
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	4		5
Accumulated Amortization	0		0
Net Balance	4		5
Electric security plan
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	0		87
Accumulated Amortization	0		(87)
Net Balance	0		0
Contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	46		44
Accumulated Amortization	(24)		(20)
Net Balance	22		24
Customer relationships & contracts
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	63		66
Accumulated Amortization	(34)		(26)
Net Balance	29		40
All other
Finite-Lived Intangible Assets, Net [Abstract]
Gross Balance	20	[4]	13	[4]
Accumulated Amortization	(3)	[4]	(2)	[4]
Net Balance	17	[4]	11	[4]
Poland wind projects | Discontinued Operations | Project development rights
Finite-Lived Intangible Assets, Net [Abstract]
Net Balance	70
Cameroon | Discontinued Operations | Contractual payment rights
Finite-Lived Intangible Assets, Net [Abstract]
Net Balance	$ 32		$ 34

[1] Represent development rights, including but not limited to, land control, various permits and right to acquire equity interests in development projects resulting from asset acquisitions by our wind operations in the U.K. The balance excludes project development rights of $70 million relating to our Poland wind operations that were fully impaired in the third quarter of 2013 and subsequently sold in November 2013. See Note 23—Discontinued Operations and Held for Sale Businesses for further information.

[2] Excludes net balance of sales concessions of $32 and $34 million as of December 31, 2013 and 2012, respectively, relating to our utility businesses in Cameroon that have been included in noncurrent assets of Discontinued Operations and Held for Sale Businesses. See Note 23—Discontinued Operations and Held for Sale Businesses for further information.

[3] Represent legal rights to receive system reliability payments from the regulator.

[4] Includes renewable energy certificates, land use rights and various other intangible assets none of which is individually significant.