Stockholders' Equity (Schedule of Stockholders' Equity) (Details) (USD $) In Millions, unless otherwise specified	9 Months Ended				9 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Redeemable Noncontrolling Interests (Non- Equity) [Member]	Sep. 30, 2014 Common Stock [Member]	Dec. 31, 2013 Common Stock [Member]	Sep. 30, 2014 Additional Paid-in Capital [Member]	Sep. 30, 2014 Treasury Stock [Member]	Dec. 31, 2013 Treasury Stock [Member]	Sep. 30, 2014 Accumulated Other Comprehensive (Loss) Income [Member]	Sep. 30, 2014 Retained Earnings	Sep. 30, 2014 Noncontrolling Interests
Equity, beginning balance	$ 3,132	$ 358	$ 1	$ 1	$ 1,256	$ (7)	$ (7)	$ (67)	$ 1,885	$ 64
Comprehensive income (loss) attributable to redeemable noncontrolling interest		59
Comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interests	27							19	(8)	16
Distributions to noncontrolling interests, net of contributions	(23)	(52)								(23)
Purchase of subsidiary shares from noncontrolling interests	(1)	(7)			(1)
Noncontrolling interests in acquired entity	31	335								31
Adjustment to redemption value of redeemable noncontrolling interests	(2)	2			(2)
Issuance of common stock in connection with the exercise of stock options	42				42
Issuance of shares in exchange for HMA common stock	736				736
Cancellation of restricted stock for tax withholdings on vested shares	(11)				(11)
Excess tax benefit from exercise of stock options	3				3
Stock-based compensation	36				36
Equity, ending balance	$ 3,970	$ 695	$ 1	$ 1	$ 2,059	$ (7)	$ (7)	$ (48)	$ 1,877	$ 88