CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment	Common Stock	Additional Paid-In Capital	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment Revision of Prior Period, Adjustment	Accumulated Other Comprehensive Losses
Beginning 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)
Repurchase of common stock	(100,000)		(20)		(99,980)
Options exercised and awards vested	1,616		25	1,591
Stock option expense	13,459			13,459
Other	(539)		(1)	(180)	(358)
Ending Balance at Dec. 31, 2018	1,096,162	$ 1,683	376	34,953	1,205,946	$ 1,683	(145,113)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	1,550						1,550
Net income (loss)	1,720				1,720
Comprehensive income (loss)	3,270
Repurchase of common stock	(26,570)		(6)		(26,564)
Options exercised and awards vested	2,181			2,181
Stock option expense	15,721			15,721
Other	(63)		1	15	(79)
Ending Balance at Dec. 31, 2019	1,090,701		371	52,870	1,181,023		(143,563)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Foreign currency translation adjustment	(6,148)						(6,148)
Net income (loss)	(30,768)				(30,768)
Comprehensive income (loss)	(36,916)
Repurchase of common stock	(25,000)		(8)		(24,992)
Shares withheld for payment of employee payroll taxes	(171)			(171)
Stock option expense	12,914			12,914
Ending Balance at Dec. 31, 2020	$ 1,041,528		$ 363	$ 65,613	$ 1,125,263		$ (149,711)