Condensed Consolidated Statements of Equity (Unaudited) (USD $) In Millions, except Share data	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Total
Balance at Dec. 31, 2012	$ 590	$ 2,015	$ 990	$ (218)	$ (8)	$ 22	$ 3,391
Balance (in Shares) at Dec. 31, 2012	117,900,000
Net income			193			11	204
Other comprehensive income				9			9	[1]
Dividends on common stock			(111)				(111)
Distributions to noncontrolling interest						(17)	(17)
Stock granted, share-based compensation, net of forfeitures		(6)					(6)
Stock issued, dividend reinvestment plan	1	5					6
Stock issued, dividend reinvestment plan (in Shares)	100,000
Stock issued, share-based compensation, net of forfeitures	3	18					21
Stock issued, share-based compensation, net of forfeitures (in Shares)	600,000
Stock-based compensation expense, net of tax		5					5
Balance at Jun. 30, 2013	594	2,037	1,072	(209)	(8)	16	3,502	[2]
Balance (in Shares) at Jun. 30, 2013	118,600,000						118,560,687
Balance at Dec. 31, 2013	595	2,054	1,063	(136)	(8)	45	3,613	[2]
Balance (in Shares) at Dec. 31, 2013	118,900,000						118,888,876
Net income			342			14	356
Other comprehensive income				3			3	[1]
Dividends on common stock			(117)				(117)
Distributions to noncontrolling interest						(17)	(17)
Stock granted, share-based compensation, net of forfeitures		(12)					(12)
Stock issued, dividend reinvestment plan		6					6
Stock issued, share-based compensation, net of forfeitures	3	17					20
Stock issued, share-based compensation, net of forfeitures (in Shares)	600,000
Stock-based compensation expense, net of tax		8					8
Balance at Jun. 30, 2014	$ 598	$ 2,073	$ 1,288	$ (133)	$ (8)	$ 42	$ 3,860	[2]
Balance (in Shares) at Jun. 30, 2014	119,500,000						119,464,063

[1] All amounts are net of income taxes. Amounts in parentheses indicate debits to accumulated other comprehensive loss.

[2] Amounts revised to include prior period adjustments. See Note 13 for additional information.