CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning Balance at Dec. 31, 2015	$ 1,324,458	$ 378	$ 0	$ 1,425,344	$ (101,264)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(49,141)				(49,141)
Net income (loss)	93,221			93,221
Comprehensive income (loss)	44,080
Options exercised and awards vested	2,206	1	2,205
Stock option expense	12,217		12,217
Excess tax benefits - stock options and awards	(2,241)		(2,241)
Repurchase of common stock	(24,234)	(4)	(6,713)	(17,517)
Other	(62)			(60)	(2)
Ending Balance at Dec. 31, 2016	1,356,424	375	5,468	1,500,988	(150,407)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	24,117				24,117
Net income (loss)	(100,639)			(100,639)
Comprehensive income (loss)	(76,522)
Options exercised and awards vested	560		560
Stock option expense	14,270		14,270
Other	(271)	(3)	(215)	(53)
Ending Balance at Dec. 31, 2017	1,294,461	372	20,083	1,400,296	(126,290)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(18,823)				(18,823)
Net income (loss)	(95,695)			(95,695)
Comprehensive income (loss)	(114,518)
Options exercised and awards vested	1,616	25	1,591
Stock option expense	13,459		13,459
Repurchase of common stock	(100,000)	(20)		(99,980)
Other	(539)	(1)	(180)	(358)
Ending Balance at Dec. 31, 2018	$ 1,096,162	$ 376	$ 34,953	$ 1,205,946	$ (145,113)