CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2017	$ 764,597	$ 702	$ 610,345	$ 550,866	$ (319,960)	$ (77,356)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(34,002)			(34,002)
Other comprehensive loss	(7,248)					(7,248)
Stock-based compensation	14,067		14,067
Shares issued and forfeited, net, under stock plans including income tax benefits	16,435		439		15,996
Repurchase of common stock	(54,527)				(54,527)
Repurchase of restricted share awards and restricted share units for tax withholdings	(2,588)				(2,588)
Cumulative effect of accounting change, ASC 606	243,981			243,981
Ending balance at Jun. 30, 2018	940,715	702	624,851	760,845	(361,079)	(84,604)
Beginning balance at Mar. 31, 2018	979,021	702	616,913	775,419	(342,316)	(71,697)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(14,574)			(14,574)
Other comprehensive loss	(12,907)					(12,907)
Stock-based compensation	7,705		7,705
Shares issued and forfeited, net, under stock plans including income tax benefits	6,558		233		6,325
Repurchase of common stock	(23,414)				(23,414)
Repurchase of restricted share awards and restricted share units for tax withholdings	(1,674)				(1,674)
Ending balance at Jun. 30, 2018	940,715	702	624,851	760,845	(361,079)	(84,604)
Beginning balance at Dec. 31, 2018	1,048,231	702	632,235	863,768	(355,857)	(92,617)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(20,238)			(20,238)
Other comprehensive loss	(409)					(409)
Stock-based compensation	20,957		20,957
Shares issued and forfeited, net, under stock plans including income tax benefits	7,476		(2,395)		9,871
Repurchase of common stock	(631)				(631)
Repurchase of restricted share awards and restricted share units for tax withholdings	(2,809)				(2,809)
Ending balance at Jun. 30, 2019	1,052,577	702	650,797	843,530	(349,426)	(93,026)
Beginning balance at Mar. 31, 2019	1,032,584	702	636,960	837,805	(351,587)	(91,296)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	5,725			5,725
Other comprehensive loss	(1,730)					(1,730)
Stock-based compensation	14,372		14,372
Shares issued and forfeited, net, under stock plans including income tax benefits	1,811		(535)		2,346
Repurchase of restricted share awards and restricted share units for tax withholdings	(185)				(185)
Ending balance at Jun. 30, 2019	$ 1,052,577	$ 702	$ 650,797	$ 843,530	$ (349,426)	$ (93,026)