Condensed Consolidated Statements of Equity (Unaudited) (USD $) In Thousands, except Share data	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Retained Earnings	Noncontrolling Interests
Beginning Balance at Dec. 31, 2010	$ 1,370,418	$ 1,139	$ 509,218	$ (3,095)	$ 858,887	$ 4,269
Beginning Balance, shares at Dec. 31, 2010		113,950,081
Vesting of restricted stock units		5	(5)
Vesting of restricted stock units, shares		521,069
Tax withholdings related to net share settlements of restricted stock units	(5,271)	(2)	(5,269)
Tax withholdings related to net share settlements of restricted stock units, shares		(179,375)
Equity-based compensation	5,962		5,962
Exercise of stock options and warrants	2,776	2	2,774
Exercise of stock options and warrants, shares		202,756
Excess tax benefit associated with equity-based compensation	2,829		2,829
Repurchase of common stock	(42,381)	(14)	(42,367)
Repurchase of common stock, shares	(1,460,399)	(1,460,399)
Cash dividends on common stock	(17,041)				(17,041)
Amounts reclassified into earnings, net of taxes	848			848
Changes in fair value of swaps, net of taxes	819			819
Distributions to noncontrolling interests	(675)					(675)
Fair value of noncontrolling interest associated with business acquired	208					208
Net income	81,398				80,952	446
Ending Balance at Jun. 30, 2011	1,399,890	1,130	473,142	(1,428)	922,798	4,248
Ending Balance, shares at Jun. 30, 2011		113,034,132
Beginning Balance at Dec. 31, 2011	1,399,687	1,109	408,721	(3,480)	988,560	4,777
Beginning Balance, shares at Dec. 31, 2011	110,907,782	110,907,782
Vesting of restricted stock units		6	(6)
Vesting of restricted stock units, shares		585,808
Tax withholdings related to net share settlements of restricted stock units	(6,010)	(2)	(6,008)
Tax withholdings related to net share settlements of restricted stock units, shares		(188,237)
Equity-based compensation	10,821		10,821
Exercise of stock options and warrants	851	1	850
Exercise of stock options and warrants, shares		80,065
Issuance of common stock, net of issuance costs of $376	369,584	120	369,464
Issuance of common stock, net of issuance costs of $376, shares		12,000,000
Excess tax benefit associated with equity-based compensation	3,283		3,283
Repurchase of common stock	(5,233)	(2)	(5,231)
Repurchase of common stock, shares	(180,875)	(180,875)
Cash dividends on common stock	(21,122)				(21,122)
Amounts reclassified into earnings, net of taxes	169			169
Changes in fair value of swaps, net of taxes	(2,555)			(2,555)
Distributions to noncontrolling interests	(94)					(94)
Net income	73,953				73,719	234
Ending Balance at Jun. 30, 2012	$ 1,823,334	$ 1,232	$ 781,894	$ (5,866)	$ 1,041,157	$ 4,917
Ending Balance, shares at Jun. 30, 2012	123,204,543	123,204,543