Consolidated Statements of Stockholders' Equity (USD $) In Thousands, except Share data	Redeemable Noncontrolling Interests (Non- Equity) [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings	Noncontrolling Interests	Total
Equity, beginning balance at Dec. 31, 2009		$ 940	$ 1,158,359	$ (6,678)	$ (221,385)	$ 1,019,399	$ 64,782	$ 2,015,417
Redeemable noncontrolling interests, beginning balance at Dec. 31, 2009	368,857
Equity, beginning balance, shares at Dec. 31, 2009		94,013,537		(975,549)
Redeemable noncontrolling interests in equity of consolidated subsidiaries	387,472
Comprehensive income (loss) attributable to redeemable noncontrolling interest	50,292
Comprehensive Income (Loss) Including Portion Attributable to Nonredeemable Noncontrolling Interests					(9,542)	279,983	18,166	288,607
Distributions to noncontrolling interests, net of contributions	(40,068)						(20,046)	(20,046)
Purchase of subsidiary shares from noncontrolling interests	(3,754)		(3,529)					(3,529)
Other reclassifications of noncontrolling interests	1,989						(1,989)	(1,989)
Adjustment to redemption value of redeemable noncontrolling interests	10,156		(10,156)					(10,156)
Issuance of common stock in connection with the exercise of stock options		22	56,916					56,938
Issuance of common stock in connection with the exercise of stock options, shares		2,194,862
Cancellation of restricted stock for tax withholdings on vested shares		(3)	(9,876)					(9,879)
Cancellation of restricted stock for tax withholdings on vested shares, shares		(295,171)
Repurchases of common stock		(34)	(113,961)					(113,995)
Repurchases of common stock, shares		(3,415,800)
Excess tax benefit from exercise of stock options			10,219					10,219
Stock-based compensation		11	38,779					38,790
Stock-based compensation, shares		1,147,434
Equity, ending balance at Dec. 31, 2010		936	1,126,751	(6,678)	(230,927)	1,299,382	60,913	2,250,377
Redeemable noncontrolling interests, ending balance at Dec. 31, 2010	387,472
Equity, ending balance, shares at Dec. 31, 2010		93,644,862		(975,549)
Redeemable noncontrolling interests in equity of consolidated subsidiaries	395,743							395,743
Comprehensive income (loss) attributable to redeemable noncontrolling interest	54,251
Comprehensive Income (Loss) Including Portion Attributable to Nonredeemable Noncontrolling Interests					46,448	201,948	21,424	269,820
Distributions to noncontrolling interests, net of contributions	(39,816)						(15,049)	(15,049)
Purchase of subsidiary shares from noncontrolling interests	(7,426)		(4,556)				(1,040)	(5,596)
Other reclassifications of noncontrolling interests	(2,099)						1,101	1,101
Adjustment to redemption value of redeemable noncontrolling interests	3,361		(3,361)					(3,361)
Issuance of common stock in connection with the exercise of stock options		6	18,910					18,916
Issuance of common stock in connection with the exercise of stock options, shares		623,341
Cancellation of restricted stock for tax withholdings on vested shares		(3)	(13,311)					(13,314)
Cancellation of restricted stock for tax withholdings on vested shares, shares		(346,419)
Repurchases of common stock		(35)	(85,790)					(85,825)
Repurchases of common stock, shares		(3,469,099)
Excess tax benefit from exercise of stock options			4,823					4,823
Stock-based compensation		11	42,542					42,553
Stock-based compensation, shares		1,094,394
Equity, ending balance at Dec. 31, 2011		915	1,086,008	(6,678)	(184,479)	1,501,330	67,349	2,464,445
Redeemable noncontrolling interests, ending balance at Dec. 31, 2011	395,743							395,743
Equity, ending balance, shares at Dec. 31, 2011		91,547,079		(975,549)				90,571,530
Redeemable noncontrolling interests in equity of consolidated subsidiaries	367,666							367,666
Comprehensive income (loss) attributable to redeemable noncontrolling interest	56,235
Comprehensive Income (Loss) Including Portion Attributable to Nonredeemable Noncontrolling Interests					39,169	265,640	23,928	328,737
Distributions to noncontrolling interests, net of contributions	(43,613)						(24,196)	(24,196)
Purchase of subsidiary shares from noncontrolling interests	(21,607)		(21,537)				(1,143)	(22,680)
Other reclassifications of noncontrolling interests	718						(624)	(624)
Adjustment to redemption value of redeemable noncontrolling interests	(19,810)		19,810					19,810
Issuance of common stock in connection with the exercise of stock options		11	20,858					20,869
Issuance of common stock in connection with the exercise of stock options, shares		1,054,075
Cancellation of restricted stock for tax withholdings on vested shares		(4)	(9,314)					(9,318)
Cancellation of restricted stock for tax withholdings on vested shares, shares		(371,946)
Net distribution to shareholders			443			(22,978)		(22,535)
Excess tax benefit from exercise of stock options			1,110					1,110
Stock-based compensation		7	40,896					40,903
Stock-based compensation, shares		696,507
Equity, ending balance at Dec. 31, 2012		929	1,138,274	(6,678)	(145,310)	1,743,992	65,314	2,796,521
Redeemable noncontrolling interests, ending balance at Dec. 31, 2012	$ 367,666							$ 367,666
Equity, ending balance, shares at Dec. 31, 2012		92,925,715		(975,549)				91,950,166