Stockholders' Equity (Schedule of Stockholders' Equity) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended						9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013 Redeemable Noncontrolling Interests (Non- Equity) [Member]	Sep. 30, 2013 Common Stock [Member]	Sep. 30, 2013 Additional Paid-in Capital [Member]	Sep. 30, 2013 Treasury Stock [Member]	Dec. 31, 2012 Treasury Stock [Member]	Sep. 30, 2013 Accumulated Other Comprehensive Income (Loss) [Member]	Sep. 30, 2013 Retained Earnings	Sep. 30, 2013 Noncontrolling Interest
Equity, beginning balance	$ 2,796,521	$ 367,666	$ 929	$ 1,138,274	$ (6,678)	$ (6,678)	$ (145,310)	$ 1,743,992	$ 65,314
Comprehensive income (loss) attributable to redeemable noncontrolling interest		34,924
Comprehensive income (loss) including portion attributable to nonredeemable noncontrolling interests	182,877						52,795	113,022	17,060
Distributions to noncontrolling interests, net of contributions	(21,177)	(39,041)							(21,177)
Purchase of subsidiary shares from noncontrolling interests	(1,311)	(4,410)		(804)					(507)
Other reclassifications of noncontrolling interests	(2,291)	2,291							(2,291)
Noncontrolling interests in acquired entity	4,599								4,599
Adjustment to redemption value of redeemable noncontrolling interests	(5,357)	5,357		(5,357)
Repurchases of Common Stock	(27,140)		(7)	(27,133)
Issuance of common stock in connection with the exercise of stock options	108,559		32	108,527
Cancellation of restricted stock for tax withholdings on vested shares	(14,699)		(3)	(14,696)
Excess tax benefit from exercise of stock options	3,432			3,432
Share-based compensation	28,951		8	28,943
Equity, ending balance	$ 3,052,964	$ 366,787	$ 959	$ 1,231,186	$ (6,678)	$ (6,678)	$ (92,515)	$ 1,857,014	$ 62,998