Stock-Based Compensation, Dividend Restrictions, And Calculations Of Earnings Per Share Of Common Stock (Calculations of Earnings Per Share Of Common Stock) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011		Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Net income from continuing operations	$ 23	$ 80	$ 95	[1]	$ 62	$ 14	$ 21	$ 76	$ 28	$ 260	$ 139	$ 223
Loss (income) from discontinued operations	(4)		(1)		2	19	(4)	(130)	8	(3)	(107)	12
Net Income	$ 19	$ 80	$ 94		$ 64	$ 33	$ 17	$ (54)	$ 36	$ 257	$ 32	$ 235
Average shares outstanding										226,000,000	224,000,000	221,000,000
Weighted Average Shares Outstanding for Computation of Basic Earnings Per Share of Common Stock										226,000,000	224,000,000	221,000,000
Weighted Average Shares Outstanding for Computation of Diluted Earnings Per Share of Common Stock										226,000,000	224,000,000	221,000,000
Basic and diluted earnings per share of common stock from continuing operations	$ 0.10	$ 0.35	$ 0.42		$ 0.27	$ 0.06	$ 0.09	$ 0.34	$ 0.13	$ 1.15	$ 0.62	$ 1.01
Basic and diluted (loss) earnings per share of common stock from discontinued operations	$ (0.02)				$ 0.01	$ 0.08	$ (0.01)	$ (0.58)	$ 0.03	$ (0.01)	$ (0.48)	$ 0.05
Basic and diluted earnings per share	$ 0.08	$ 0.35	$ 0.42		$ 0.28	$ 0.14	$ 0.08	$ (0.24)	$ 0.16	$ 1.14	$ 0.14	$ 1.06
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount										14,900	280,266	334,966

[1] Includes $39 million pre-tax ($3 million after-tax) gain from the early termination of cross-border energy leases held in trust.