Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Accumulated Other Comprehensive Income (Loss)	Total
Balance at Dec. 31, 2013	$ 27	$ 511,075	$ (1,218)	$ (346,117)	$ 5,739	$ 169,506
Balance (in shares) at Dec. 31, 2013	27,556
Increase (Decrease) in Stockholders' Equity
Net income (loss)				(11,266)		(11,266)
Foreign currency translation adjustments					(4,150)	(4,150)
Amortization of actuarial gains/losses and other adjustments from pension plan					(313)	(313)
Exercise of stock options	$ 1	2,894				2,895
Exercise of stock options (in shares)	605
Issuance of shares under Employee Stock Purchase Plan		446				446
Issuance of shares under Employee Stock Purchase Plan (in shares)	50
Issuance of restricted common shares		(7)				(7)
Issuance of restricted common shares (in shares)	2
Stock-based compensation expense		4,745				4,745
Balance at Dec. 31, 2014	$ 28	519,153	(1,218)	(357,383)	1,276	161,856
Balance (in shares) at Dec. 31, 2014	28,213
Increase (Decrease) in Stockholders' Equity
Net income (loss)				14,678		14,678
Foreign currency translation adjustments					(2,664)	(2,664)
Amortization of actuarial gains/losses and other adjustments from pension plan					(43)	(43)
Exercise of stock options	$ 1	3,920				3,921
Exercise of stock options (in shares)	759
Issuance of shares under Employee Stock Purchase Plan		441				441
Issuance of shares under Employee Stock Purchase Plan (in shares)	47
Issuance of restricted common shares		(7)				(7)
Issuance of restricted common shares (in shares)	7
Stock-based compensation expense		5,582				5,582
Balance at Dec. 31, 2015	$ 29	529,089	(1,218)	(342,705)	(1,431)	183,764
Balance (in shares) at Dec. 31, 2015	29,026
Increase (Decrease) in Stockholders' Equity
Net income (loss)				11,001		11,001
Foreign currency translation adjustments					(847)	(847)
Amortization of actuarial gains/losses and other adjustments from pension plan					(1)	(1)
Exercise of stock options	$ 1	2,237				2,238
Exercise of stock options (in shares)	392
Issuance of shares under Employee Stock Purchase Plan		325				325
Issuance of shares under Employee Stock Purchase Plan (in shares)	22
Issuance of restricted common shares		(11)				(11)
Issuance of restricted common shares (in shares)	108
Treasury shares returned to authorized, Value		(1,218)	$ 1,218			0
Treasury shares returned to authorized, Shares	(30)
Reverse stock split issuance costs		(145)				(145)
Stock-based compensation expense		5,131				5,131
Balance at Dec. 31, 2016	$ 30	$ 535,408		$ (331,704)	$ (2,279)	$ 201,455
Balance (in shares) at Dec. 31, 2016	29,518