Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in-Capital	Accumulated Other Comprehensive Loss	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2017		64,075,000	10,020,000
Beginning balance at Dec. 31, 2017	$ 284,545	$ 6	$ (55,873)	$ 235,199	$ (19,229)	$ 124,442
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(46,921)					(46,921)
Total other comprehensive income - foreign currency translation adjustments	(3,951)				(3,951)
Comprehensive loss	(50,872)
Issuance of common stock upon exercise of stock awards, net of withheld shares (in shares)		359,000
Issuance of common stock upon exercise of stock awards, net of withheld shares	$ (438)			(438)
Acquisition of treasury shares (in shares)	2,667,732		2,668,000
Acquisition of treasury shares	$ (25,598)		$ (25,598)
Stock-based compensation expense	3,624			3,624
Ending balance (in shares) at Sep. 30, 2018		64,434,000	12,688,000
Ending balance at Sep. 30, 2018	211,896	$ 6	$ (81,471)	238,385	(23,180)	78,156
Beginning balance (in shares) at Jun. 30, 2018		64,372,000	12,688,000
Beginning balance at Jun. 30, 2018	257,791	$ 6	$ (81,471)	237,634	(21,472)	123,094
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(44,937)					(44,937)
Total other comprehensive income - foreign currency translation adjustments	(1,708)				(1,708)
Comprehensive loss	(46,646)
Issuance of common stock upon exercise of stock awards, net of withheld shares (in shares)		62,000
Issuance of common stock upon exercise of stock awards, net of withheld shares	(50)			(50)
Stock-based compensation expense	801			801
Ending balance (in shares) at Sep. 30, 2018		64,434,000	12,688,000
Ending balance at Sep. 30, 2018	211,896	$ 6	$ (81,471)	238,385	(23,180)	78,156
Beginning balance (in shares) at Dec. 31, 2018		64,495,000	12,688,000
Beginning balance at Dec. 31, 2018	183,091	$ 6	$ (81,471)	239,960	(24,309)	48,905
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(5,805)					(5,805)
Total other comprehensive income - foreign currency translation adjustments	(736)				(736)
Comprehensive loss	(6,541)
Issuance of common stock upon exercise of stock awards, net of withheld shares (in shares)		307,000
Issuance of common stock upon exercise of stock awards, net of withheld shares	(179)			(179)
Stock-based compensation expense	3,925			3,925
Ending balance (in shares) at Sep. 30, 2019		64,802,000	12,688,000
Ending balance at Sep. 30, 2019	180,455	$ 6	$ (81,471)	243,706	(25,045)	43,259
Beginning balance (in shares) at Jun. 30, 2019		64,629,000	12,688,000
Beginning balance at Jun. 30, 2019	182,669	$ 6	$ (81,471)	242,010	(23,309)	45,433
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(2,174)
Total other comprehensive income - foreign currency translation adjustments	(1,736)				(1,736)
Comprehensive loss	(3,910)
Issuance of common stock upon exercise of stock awards, net of withheld shares (in shares)		173,000
Issuance of common stock upon exercise of stock awards, net of withheld shares	(88)			(88)
Stock-based compensation expense	1,784			1,784
Ending balance (in shares) at Sep. 30, 2019		64,802,000	12,688,000
Ending balance at Sep. 30, 2019	$ 180,455	$ 6	$ (81,471)	$ 243,706	$ (25,045)	$ 43,259