Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Accumulated Deficit
Beginning balance at Dec. 31, 2016	$ 29,938	$ 1	$ 126,875	$ (1)	$ (96,937)
Beginning balance (in shares) at Dec. 31, 2016		11,711
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock purchase plans	130		130
Issuance of common stock under employee stock option and stock purchase plans (in shares)		173
Common stock withheld in lieu of income tax withholding from share-based compensation	(49)		(49)
Common stock withheld in lieu of income tax withholding from share-based compensation (in shares)		(15)
Stock-based compensation	807		807
Stock-based compensation reversal	(270)		(270)
Foreign currency translation adjustment	3			3
Net loss	(11,267)				(11,267)
Ending balance at Dec. 31, 2017	19,292	$ 1	127,493	2	(108,204)
Ending balance (in shares) at Dec. 31, 2017		11,869
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock purchase plans	28		28
Issuance of common stock under employee stock option and stock purchase plans (in shares)		249
Common stock withheld in lieu of income tax withholding from share-based compensation	(62)		(62)
Common stock withheld in lieu of income tax withholding from share-based compensation (in shares)		(27)
Stock-based compensation	908		908
Foreign currency translation adjustment	(3)			(3)
Net loss	(9,111)				(9,111)
Ending balance at Dec. 31, 2018	11,052	$ 1	128,367	(1)	(117,315)
Ending balance (in shares) at Dec. 31, 2018		12,091
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock option and stock purchase plans	5		5
Issuance of common stock under employee stock option and stock purchase plans (in shares)		387
Common stock withheld in lieu of income tax withholding from share-based compensation	(116)		(116)
Common stock withheld in lieu of income tax withholding from share-based compensation (in shares)		(50)
Stock-based compensation	616		616
Foreign currency translation adjustment	(2)			(2)
Net loss	(7,373)				(7,373)
Ending balance at Dec. 31, 2019	$ 3,996	$ 1	$ 128,872	$ (3)	$ (124,874)
Ending balance (in shares) at Dec. 31, 2019		12,428