Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance, shares at Dec. 31, 2017		37,200
Balance as of December 31, 2018 at Dec. 31, 2017	$ 106,101	$ 3,717	$ 337,541	$ (247,233)	$ 12,076
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation, shares		280
Share-based compensation	1,252	$ 28	1,224
Issuance of common stock for bonuses and director fees, shares		520
Issuance of common stock for bonuses and director fees	3,184	$ 52	3,132
Net loss	(9,205)			(9,205)
Foreign currency translation adjustments	1,437				1,437
Pension adjustment, net of tax provision (benefit)	19				19
Ending balance, shares at Mar. 31, 2018		38,000
Balance as of March 31, 2019 at Mar. 31, 2018	103,066	$ 3,797	341,897	(256,160)	13,532
Beginning balance, shares at Dec. 31, 2018		45,996
Balance as of December 31, 2018 at Dec. 31, 2018	90,591	$ 4,597	369,793	(283,503)	(296)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation, shares		294
Share-based compensation	1,671	$ 29	1,642
Issuance of common stock for bonuses and director fees, shares		211
Issuance of common stock for bonuses and director fees	1,756	$ 21	1,735
Net loss	(17,620)			(17,620)
Foreign currency translation adjustments	(461)				(461)
Ending balance, shares at Mar. 31, 2019		46,501
Balance as of March 31, 2019 at Mar. 31, 2019	$ 75,937	$ 4,647	$ 373,170	$ (301,123)	$ (757)