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	569,681		1,064	618,626	(67,873)	148,802		(139,086)
Net income (loss)	5,588					5,588
Employee stock options, restricted stock and employee stock purchase plan	(277)		3	(5,524)		(995)		6,239
Stock-based compensation expense	6,874			6,874
Treasury shares purchased at cost	(15,537)							(15,537)
Foreign currency translation, net of tax	(200)				(200)
Ending 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	569,788		1,064	622,554	(69,594)	150,084		(134,320)
Beginning balance at Mar. 31, 2019	569,788		1,064	622,554	(69,594)	150,084		(134,320)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	566,129		1,067	618,626	(67,873)	153,395		(139,086)
Net income (loss)	4,306					4,306
Employee stock options, restricted stock and employee stock purchase plan	(1,067)		3	(5,833)		(995)		5,758
Stock-based compensation expense	1,905			1,905
Treasury shares purchased at cost	(10,524)							(10,524)
Foreign currency translation, net of tax	1,721				1,721
Ending 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	566,129		1,067	618,626	(67,873)	153,395		(139,086)
Cumulative effect of accounting change	548,645		1,067	620,626	(67,947)	134,119	$ (735)	(139,220)
Beginning balance at Dec. 31, 2019	548,645		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)	1,067	620,626	(73,308)	93,292	$ (735)	(139,220)
Net income (loss)	(38,392)					(38,392)
Employee stock options, restricted stock and employee stock purchase plan	203		7	(434)		(1,700)		2,330
Stock-based compensation expense	3,077			3,077
Foreign currency translation, net of tax	(5,361)				(5,361)
Ending balance at Jun. 30, 2020	507,437	(735)	1,074	623,269	(73,308)	93,292		(136,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	530,359		1,067	622,115	(75,440)	120,501		(137,884)
Beginning balance at Mar. 31, 2020	530,359		1,067	622,115	(75,440)	120,501		(137,884)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	530,359	(735)	1,074	623,269	(73,308)	93,292		(136,890)
Net income (loss)	(26,244)					(26,244)
Employee stock options, restricted stock and employee stock purchase plan	(295)		7	(331)		(965)		994
Stock-based compensation expense	1,485			1,485
Foreign currency translation, net of tax	2,132				2,132
Ending balance at Jun. 30, 2020	507,437	(735)	1,074	623,269	(73,308)	93,292		(136,890)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change	$ 507,437	$ (735)	$ 1,074	$ 623,269	$ (73,308)	$ 93,292		$ (136,890)