Condensed Consolidated Statements of Shareholders’ Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]
Beginning balance (in shares) at Dec. 31, 2013		173,452,896
Beginning balance at Dec. 31, 2013	$ 961,439	$ 1,735	$ 851,017	$ 117,127	$ (8,440)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	66,767			66,767
Share-based compensation	15,426		15,426
Excess tax benefit from share-based compensation	3,010		3,010
Shares issued in connection with share-based compensation (in shares)		659,672
Shares issued in connection with share-based compensation	1,287	$ 6	1,281
Minimum tax withholdings related to net share settlements of restricted stock units	(3,491)		(3,491)
Conversion of phantom shares into restricted stock units	956		956
Other comprehensive loss	271				271
Ending balance (in shares) at Jun. 30, 2014		174,112,568
Ending balance at Jun. 30, 2014	1,045,665	$ 1,741	868,199	183,894	(8,169)
Beginning balance (in shares) at Dec. 31, 2014		174,388,132
Beginning balance at Dec. 31, 2014	1,076,487	$ 1,744	878,549	257,312	(61,118)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	70,791			70,791
Share-based compensation	20,433		20,433
Excess tax benefit from share-based compensation	11,345		11,345
Shares issued in connection with share-based compensation (in shares)		1,233,481
Shares issued in connection with share-based compensation	3,570	$ 12	3,558
Minimum tax withholdings related to net share settlements of restricted stock units	(7,565)		(7,565)
Other comprehensive loss	(27,023)				(27,023)
Ending balance (in shares) at Jun. 30, 2015		175,621,613
Ending balance at Jun. 30, 2015	$ 1,148,038	$ 1,756	$ 906,320	$ 328,103	$ (88,141)