Condensed Consolidated Statement of Changes in Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Dec. 31, 2016					$ (331)
Increase (Decrease) in Stockholders' Equity
Net loss	$ (9,160)
Foreign currency translation adjustment	127
Ending balance at Jun. 30, 2017					(204)
Beginning balance at Mar. 31, 2017					(245)
Increase (Decrease) in Stockholders' Equity
Net loss	(2,300)
Foreign currency translation adjustment	41
Ending balance at Jun. 30, 2017					(204)
Beginning balance at Dec. 31, 2017	83,139	$ 5	$ (8,443)	$ 288,277	(232)	$ (196,468)
Balance (in shares) at Dec. 31, 2017		55,136,038	3,845,496
Increase (Decrease) in Stockholders' Equity
Exercise of stock options awards	1,178			1,178
Exercise of stock options awards (in shares)		399,246
Stock-based compensation expense	1,836			1,836
Common stock issued for settlement of restricted stock units net of 222,202 shares withheld to satisfy income tax withholding obligations	(1,014)			(1,014)
Common stock issued for settlement of restricted stock units net of 222,202 shares withheld to satisfy income tax withholding obligations (in shares)		639,565
Common stock issuance in connection with employee stock purchase plan	239			239
Common stock issuance about employee stock purchase plan (in shares)		84,415
Net loss	(9,222)					(9,222)
Foreign currency translation adjustment	(272)				(272)
Ending balance at Jun. 30, 2018	75,884	$ 5	$ (8,443)	290,516	(504)	(205,690)
Balance (in shares) at Jun. 30, 2018		56,259,264	3,845,496
Beginning balance at Mar. 31, 2018					(302)
Increase (Decrease) in Stockholders' Equity
Net loss	(3,121)
Foreign currency translation adjustment	(202)
Ending balance at Jun. 30, 2018	$ 75,884	$ 5	$ (8,443)	$ 290,516	$ (504)	$ (205,690)
Balance (in shares) at Jun. 30, 2018		56,259,264	3,845,496