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			150			10	160
Other comprehensive income				7			7
Dividends on common stock			(55)				(55)
Distributions to noncontrolling interest						(17)	(17)
Stock granted, share-based compensation, net of forfeitures		(6)					(6)
Stock issued, dividend reinvestment plan	1	2					3
Stock issued, share-based compensation, net of forfeitures	1	6					7
Stock issued, share-based compensation, net of forfeitures (in Shares)	200,000
Stock-based compensation expense, net of tax		3					3
Balance at Mar. 31, 2013	592	2,020	1,085	(211)	(8)	15	3,493	[1],[2]
Balance (in Shares) at Mar. 31, 2013	118,100,000						118,123,770
Balance at Dec. 31, 2013	595	2,054	1,063	(136)	(8)	45	3,613	[1],[2]
Balance (in Shares) at Dec. 31, 2013	118,900,000						118,888,876
Net income			284			12	296
Other comprehensive income				1			1
Dividends on common stock			(58)				(58)
Distributions to noncontrolling interest						(17)	(17)
Stock granted, share-based compensation, net of forfeitures		(11)					(11)
Stock issued, dividend reinvestment plan		2					2
Stock issued, share-based compensation, net of forfeitures	2	12					14
Stock issued, share-based compensation, net of forfeitures (in Shares)	300,000
Stock-based compensation expense, net of tax		3					3
Balance at Mar. 31, 2014	$ 597	$ 2,060	$ 1,289	$ (135)	$ (8)	$ 40	$ 3,843	[1],[2]
Balance (in Shares) at Mar. 31, 2014	119,200,000						119,247,421

[1] Reflects the reclassification of the Tropical Shipping amounts as held for sale. See Note 12 for additional information.

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