Consolidated Statements of Changes in Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid in Capital	Accumulated Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Interests
Balance at Dec. 31, 2009	$ 1,762,818	$ 174	$ 71,368	$ 1,774,625	$ (100,090)		$ 16,741
Balance (in shares) at Dec. 31, 2009		173,000,000
Increase (Decrease) In Shareholders' Equity
Net income	502,413			496,405			6,008
Other comprehensive income	16,372				15,333		1,039
Purchase of noncontrolling interests	(20,167)		(12,375)				(7,792)
Acquisitions resulting in noncontrolling interests	10,285						10,285
Distributions to shareholders of noncontrolling interests	(4,421)						(4,421)
Stock options exercised, including tax benefit	60,479	2	60,477
Stock options exercised, including tax benefit (in shares)		3,000,000
Dividends declared ($0.42, $0.06 and $0.06 per common share) for the year ended December 31, 2012, 2011 and 2010, respectively	(10,449)			(10,449)
Stock-based compensation	25,385		25,385
Balance at Dec. 31, 2010	2,342,715	176	144,855	2,260,581	(84,757)		21,860
Balance (in shares) at Dec. 31, 2010		176,000,000
Increase (Decrease) In Shareholders' Equity
Net income	528,842			524,191			4,651
Other comprehensive income	(34,825)				(35,300)		475
Purchase of noncontrolling interests	(24,854)		(15,962)				(8,892)
Distributions to shareholders of noncontrolling interests	(5,077)						(5,077)
Purchase of treasury stock	(672,191)					(672,191)
Retirement of treasury stock		(13)		(672,178)		672,191
Retirement of treasury stock (in shares)		(13,000,000)
Stock options exercised, including tax benefit	31,594		31,594
Dividends declared ($0.42, $0.06 and $0.06 per common share) for the year ended December 31, 2012, 2011 and 2010, respectively	(10,097)			(10,097)
Stock-based compensation	28,679		28,679
Balance at Dec. 31, 2011	2,184,786	163	189,166	2,102,497	(120,057)		13,017
Balance (in shares) at Dec. 31, 2011	163,122,474	163,000,000
Increase (Decrease) In Shareholders' Equity
Net income	559,508			555,317			4,191
Other comprehensive income	3,274				3,053		221
Distributions to shareholders of noncontrolling interests	(5,206)						(5,206)
Purchase of treasury stock	(380,023)					(380,023)
Retirement of treasury stock		(6)		(380,017)		380,023
Retirement of treasury stock (in shares)		(6,000,000)
Stock options exercised, including tax benefit	116,108	3	116,105
Stock options exercised, including tax benefit (in shares)		3,000,000
Dividends declared ($0.42, $0.06 and $0.06 per common share) for the year ended December 31, 2012, 2011 and 2010, respectively	(67,677)			(67,677)
Stock-based compensation	31,412		31,412
Balance at Dec. 31, 2012	$ 2,442,182	$ 160	$ 336,683	$ 2,210,120	$ (117,004)		$ 12,223
Balance (in shares) at Dec. 31, 2012	159,857,738	160,000,000