CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Beginning Balance at Dec. 31, 2012	$ 2,640,657	$ 1,841	$ 863,558	$ 2,548,542	$ 21,767	$ (795,051)
Beginning Balance (in shares) at Dec. 31, 2012		184,060,000
Net income (loss)	188,009			188,009
Foreign currency translation adjustment	(7,691)				(7,691)
Issuance of restricted stock (in shares)		1,312,000
Issuance of restricted stock		$ 13	(13)
Vesting of restricted stock units (in shares)		9,000
Forfeitures of restricted stock (in shares)		(84,000)
Forfeitures of restricted stock		$ (1)	1
Exercise of stock options (in shares)		1,190,000
Exercise of stock options	19,286	$ 12	19,274
Stock-based compensation	25,891		25,891
Tax benefit (expense) related to stock-based compensation	4,794		4,794
Payment of cash dividends	(29,112)			(29,112)
Purchase of treasury stock	(85,837)					(85,837)
Ending Balance at Dec. 31, 2013	2,755,997	$ 1,865	913,505	2,707,439	14,076	(880,888)
Ending Balance (in shares) at Dec. 31, 2013		186,487,000
Net income (loss)	162,664			162,664
Foreign currency translation adjustment	(7,613)				(7,613)
Issuance of restricted stock (in shares)		1,102,000
Issuance of restricted stock		$ 11	(11)
Vesting of restricted stock units (in shares)		10,000
Vesting of restricted stock units	1	$ 1
Forfeitures of restricted stock (in shares)		(61,000)
Forfeitures of restricted stock		$ (1)	1
Exercise of stock options (in shares)		1,725,000
Exercise of stock options	35,435	$ 17	35,418
Stock-based compensation	27,032		27,032
Tax benefit (expense) related to stock-based compensation	8,729		8,729
Payment of cash dividends	(58,288)			(58,288)
Purchase of treasury stock	(18,147)					(18,147)
Ending Balance at Dec. 31, 2014	$ 2,905,810	$ 1,893	984,674	2,811,815	6,463	(899,035)
Ending Balance (in shares) at Dec. 31, 2014	189,262,876	189,263,000
Net income (loss)	$ (294,486)			(294,486)
Foreign currency translation adjustment	(10,556)				(10,556)
Issuance of restricted stock (in shares)		1,180,000
Issuance of restricted stock		$ 12	(12)
Vesting of restricted stock units (in shares)		14,000
Forfeitures of restricted stock (in shares)		(82,000)
Forfeitures of restricted stock		$ (1)	1
Stock-based compensation	28,510		28,510
Tax benefit (expense) related to stock-based compensation	(1,362)		(1,362)
Payment of cash dividends	(58,775)			(58,775)
Purchase of treasury stock	(8,010)					(8,010)
Ending Balance at Dec. 31, 2015	$ 2,561,131	$ 1,904	$ 1,011,811	$ 2,458,554	$ (4,093)	$ (907,045)
Ending Balance (in shares) at Dec. 31, 2015	190,374,801	190,375,000