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			1,111		$ 1,111
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)
Net loss				(10,313)	(10,313)
Ending balance (shares) at Jun. 30, 2019	13,146,831	0
Ending balance, amount at Jun. 30, 2019	$ 13	$ 0	362,737	(338,029)	24,721
Beginning balance (shares) at Mar. 31, 2019	13,116,462	0
Beginning balance, amount at Mar. 31, 2019	$ 13	$ 0	362,076	(333,076)	29,013
Share-based compensation			560		$ 560
Issuance of common stock upon exercise of stock options (shares)	57,036				57,036
Issuance of common stock upon exercise of stock options, amount			101		$ 101
Cancellation of restricted stock (shares)	(26,667)
Net loss				(4,953)	(4,953)
Ending balance (shares) at Jun. 30, 2019	13,146,831	0
Ending balance, amount at Jun. 30, 2019	$ 13	$ 0	362,737	(338,029)	24,721
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			1,028		$ 1,028
Issuance of common stock upon exercise of stock options (shares)					0
Net loss				(5,435)	$ (5,435)
Ending balance (shares) at Jun. 30, 2020	13,146,831	0
Ending balance, amount at Jun. 30, 2020	$ 13	$ 0	365,056	(348,380)	16,689
Beginning balance (shares) at Mar. 31, 2020	13,146,831	0
Beginning balance, amount at Mar. 31, 2020	$ 13	$ 0	364,537	(347,006)	17,544
Share-based compensation			519		$ 519
Issuance of common stock upon exercise of stock options (shares)					0
Net loss				(1,374)	$ (1,374)
Ending balance (shares) at Jun. 30, 2020	13,146,831	0
Ending balance, amount at Jun. 30, 2020	$ 13	$ 0	$ 365,056	$ (348,380)	$ 16,689