Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative effect of accounting change	Common Stock	Paid-In Capital	Accumulated Other Comprehensive Loss	Retained Earnings	Retained Earnings Cumulative effect of accounting change	Treasury Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 569,681		$ 1,064	$ 617,276	$ (67,673)	$ 148,802		$ (129,788)
Beginning balance at Dec. 31, 2018	569,681		1,064	617,276	(67,673)	148,802		(129,788)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	559,631		1,064	618,632	(67,673)	148,802		(129,788)
Net loss	4,147					4,147
Employee stock options, restricted stock and employee stock purchase plan	(444)		3	(8,019)		(1,646)		9,218
Stock-based compensation expense	9,375			9,375
Treasury shares purchased at cost	(19,031)							(19,031)
Foreign currency translation, net of tax	(4,097)				(4,097)
Ending balance at Sep. 30, 2019	559,631		1,067	618,632	(71,770)	151,303		(139,601)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	566,129		1,067	618,626	(67,873)	153,395		(139,086)
Beginning balance at Jun. 30, 2019	566,129		1,067	618,626	(67,873)	153,395		(139,086)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	559,631		1,067	618,632	(71,770)	151,303		(139,601)
Net loss	(1,441)					(1,441)
Employee stock options, restricted stock and employee stock purchase plan	(167)			(2,495)		(651)		2,979
Stock-based compensation expense	2,501			2,501
Treasury shares purchased at cost	(3,494)							(3,494)
Foreign currency translation, net of tax	(3,897)				(3,897)
Ending balance at Sep. 30, 2019	559,631		1,067	618,632	(71,770)	151,303		(139,601)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	559,631		1,067	618,632	(71,770)	151,303		(139,601)
Cumulative effect of accounting change	548,645	$ (735)	1,067	620,626	(67,947)	134,119	$ (735)	(139,220)
Beginning balance at Dec. 31, 2019	548,645	(735)	1,067	620,626	(67,947)	134,119	(735)	(139,220)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	548,645	$ (735)	1,076	620,626	(67,947)	69,422	$ (735)	(139,220)
Net loss	(62,262)					(62,262)
Employee stock options, restricted stock and employee stock purchase plan	466		9	(167)		(1,700)		2,324
Stock-based compensation expense	4,869			4,869
Foreign currency translation, net of tax	(1,900)				(1,900)
Ending balance at Sep. 30, 2020	489,083		1,076	625,328	(69,847)	69,422		(136,896)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	507,437		1,074	623,269	(73,308)	93,292		(136,890)
Beginning balance at Jun. 30, 2020	507,437		1,074	623,269	(73,308)	93,292		(136,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	507,437		1,076	625,328	(69,847)	69,422		(136,896)
Net loss	(23,870)					(23,870)
Employee stock options, restricted stock and employee stock purchase plan	263		2	267				(6)
Stock-based compensation expense	1,792			1,792
Foreign currency translation, net of tax	3,461				3,461
Ending balance at Sep. 30, 2020	489,083		1,076	625,328	(69,847)	69,422		(136,896)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 489,083		$ 1,076	$ 625,328	$ (69,847)	$ 69,422		$ (136,896)