Condensed Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]
Balance at Dec. 31, 2013	$ 3,613	$ 595	$ 2,054	$ 1,063	$ (136)	$ (8)	$ 45
Balance, shares (in Shares) at Dec. 31, 2013		118,900,000
Net income	356			342			14
Other comprehensive income	3				3
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	20	$ 3	17
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	$ 3,860	$ 598	2,073	1,288	(133)	(8)	42
Balance, shares (in Shares) at Jun. 30, 2014	119,464,063	119,500,000
Balance at Dec. 31, 2014	$ 3,828	$ 599	2,087	1,312	(206)	(8)	44
Balance, shares (in Shares) at Dec. 31, 2014	119,647,149	119,600,000
Net income	$ 249			235			14
Other comprehensive income	38				37		1
Dividends on common stock	(122)			(122)
Distributions to noncontrolling interest	(18)						(18)
Stock granted, share-based compensation, net of forfeitures	(13)		(13)
Stock issued, dividend reinvestment plan	6	$ 1	5
Stock issued, dividend reinvestment plan (in Shares)		100,000
Stock issued, share-based compensation, net of forfeitures	15	$ 1	14
Stock issued, share-based compensation, net of forfeitures (in Shares)		400,000
Stock-based compensation expense, net of tax	6		6
Balance at Jun. 30, 2015	$ 3,989	$ 601	$ 2,099	$ 1,425	$ (169)	$ (8)	$ 41
Balance, shares (in Shares) at Jun. 30, 2015	120,081,995	120,100,000