Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Loss [Member]	Accumulated Deficit [Member]
BALANCE at Dec. 31, 2014	$ 75,029	$ 297	$ 210,989	$ (119,878)	$ (220)	$ (16,159)
BALANCE, Shares at Dec. 31, 2014		29,736,000		(18,296,000)
Issuance of common stock related to employee stock plans	1,488		(2,258)	$ 3,746
Issuance of common stock related to employee stock plans, Shares				468,000
Repurchases of common stock	(332)			$ (332)
Repurchases of common stock, Shares				(46,000)
Share-based compensation expense	1,593		1,593
Currency translation adjustment	(334)				(334)
Net loss	(4,060)					(4,060)
BALANCE at Dec. 31, 2015	73,384	$ 297	210,324	$ (116,464)	(554)	(20,219)
BALANCE, Shares at Dec. 31, 2015		29,736,000		(17,874,000)
Issuance of common stock related to employee stock plans	$ 3,964		(4,165)	$ 8,129
Issuance of common stock related to employee stock plans, Shares				1,016,000
Repurchases of common stock, Shares	0
Share-based compensation expense	$ 1,286		1,286
Currency translation adjustment	(26)				(26)
Net loss	(2,834)					(2,834)
BALANCE at Dec. 31, 2016	75,774	$ 297	207,445	$ (108,335)	(580)	(23,053)
BALANCE, Shares at Dec. 31, 2016		29,736,000		(16,858,000)
Issuance of common stock related to employee stock plans	5,219		(5,718)	$ 10,937
Issuance of common stock related to employee stock plans, Shares				1,367,000
Repurchases of common stock	$ (1,286)			$ (1,286)
Repurchases of common stock, Shares	(199,053)			(199,000)
Share-based compensation expense	$ 1,022		1,022
Currency translation adjustment	(2)				(2)
Net loss	(29,136)					(29,136)
BALANCE at Dec. 31, 2017	52,983	$ 297	$ 202,749	$ (98,684)	$ (582)	(50,797)
BALANCE, Shares at Dec. 31, 2017		29,736,000		(15,690,000)
Impact of adoption of Stock compensation - Improvements to employee share-based payment accounting	$ 1,392					$ 1,392