Stockholders' Equity (Schedule of Stockholders' Equity) (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended				3 Months Ended			3 Months Ended
	Dec. 17, 2012	Mar. 31, 2014	Mar. 31, 2014 Redeemable Noncontrolling Interests (Non- Equity) [Member]	Mar. 31, 2014 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Mar. 31, 2014 Additional Paid-in Capital [Member]	Mar. 31, 2014 Treasury Stock [Member]	Dec. 31, 2013 Treasury Stock [Member]	Mar. 31, 2014 Accumulated Other Comprehensive (Loss) Income [Member]	Mar. 31, 2014 Retained Earnings	Mar. 31, 2014 Noncontrolling Interests
Equity, beginning balance		$ 3,132	$ 358	$ 1	$ 1	$ 1,256	$ (7)	$ (7)	$ (67)	$ 1,885	$ 64
Equity, beginning balance, shares		95,011,483
Comprehensive income (loss) attributable to redeemable noncontrolling interest			11
Comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interests		(98)							9	(111)	4
Distributions to noncontrolling interests, net of contributions		(7)	(12)								(7)
Purchase of subsidiary shares from noncontrolling interests		(1)	(4)			(1)
Noncontrolling interests in acquired entity		20	335								20
Adjustment to redemption value of redeemable noncontrolling interests		(4)	4			(4)
Issuance of common stock in connection with the exercise of stock options		6				6
Issuance of shares in exchange for HMA common stock		736				736
Cancellation of restricted stock for tax withholdings on vested shares		(11)				(11)
Net distribution to shareholders	(23)
Excess tax benefit from exercise of stock options		2				2
Stock-based compensation		11				11
Equity, ending balance		$ 3,786	$ 692	$ 1	$ 1	$ 1,995	$ (7)	$ (7)	$ (58)	$ 1,774	$ 81
Equity, ending balance, shares		115,260,904