CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Preferred Stock	Additional Paid-In Capital	Accumulated Deficit	Total
Beginning balance (shares) at Dec. 31, 2018	12,960,450	0
Beginning balance, amount at Dec. 31, 2018	$ 13	$ 0	$ 361,218	$ (327,716)	$ 33,515
Share-based compensation			1,762		$ 1,762
Issuance of common stock upon exercise of stock options (shares)	213,048				213,048
Issuance of common stock upon exercise of stock options, amount			408		$ 408
Cancellation of restricted stock (shares)	(26,667)
Cancellation of restricted stock, amount					0
Net loss				(12,052)	(12,052)
Ending balance (shares) at Sep. 30, 2019	13,146,831	0
Ending balance, amount at Sep. 30, 2019	$ 13	$ 0	363,388	(339,768)	23,633
Beginning balance (shares) at Jun. 30, 2019	13,146,831	0
Beginning balance, amount at Jun. 30, 2019	$ 13	$ 0	362,737	(338,029)	24,721
Share-based compensation			651		$ 651
Issuance of common stock upon exercise of stock options (shares)					0
Net loss				(1,739)	$ (1,739)
Ending balance (shares) at Sep. 30, 2019	13,146,831	0
Ending balance, amount at Sep. 30, 2019	$ 13	$ 0	363,388	(339,768)	23,633
Beginning balance (shares) at Dec. 31, 2019	13,146,831	0
Beginning balance, amount at Dec. 31, 2019	$ 13	$ 0	364,028	(342,945)	21,096
Share-based compensation			1,525		$ 1,525
Issuance of common stock upon exercise of stock options (shares)	22,213				22,213
Issuance of common stock upon exercise of stock options, amount			74		$ 74
Net loss				(5,883)	(5,883)
Ending balance (shares) at Sep. 30, 2020	13,169,044	0
Ending balance, amount at Sep. 30, 2020	$ 13	$ 0	365,627	(348,828)	16,812
Beginning balance (shares) at Jun. 30, 2020	13,146,831	0
Beginning balance, amount at Jun. 30, 2020	$ 13	$ 0	365,056	(348,380)	16,689
Share-based compensation			497		$ 497
Issuance of common stock upon exercise of stock options (shares)	22,213				22,213
Issuance of common stock upon exercise of stock options, amount			74		$ 74
Net loss				(448)	(448)
Ending balance (shares) at Sep. 30, 2020	13,169,044	0
Ending balance, amount at Sep. 30, 2020	$ 13	$ 0	$ 365,627	$ (348,828)	$ 16,812