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, 2017	13,059,341	0
Beginning balance, amount at Dec. 31, 2017	$ 13	$ 0	$ 356,054	$ (288,900)	$ 67,167
Share-based compensation			4,866		$ 4,866
Issuance of common stock upon exercise of stock options (shares)	28,467				28,467
Issuance of common stock upon exercise of stock options, amount			98		$ 98
Cancellation of restricted stock	(188,333)
Issuance of common stock, (shares)	60,975
Issuance of common stock, amount			200		200
Net loss				(38,816)	(38,816)
Ending balance (shares) at Dec. 31, 2018	12,960,450	0
Ending balance, amount at Dec. 31, 2018	$ 13	$ 0	361,218	(327,716)	33,515
Share-based compensation			2,402		$ 2,402
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	(26,667)
Net loss				(15,229)	(15,229)
Ending balance (shares) at Dec. 31, 2019	13,146,831	0
Ending balance, amount at Dec. 31, 2019	$ 13	$ 0	364,028	(342,945)	21,096
Share-based compensation			1,984		$ 1,984
Issuance of common stock upon exercise of stock options (shares)	22,373				22,373
Issuance of common stock upon exercise of stock options, amount	$ 0		75		$ 75
Net loss				(6,820)	(6,820)
Ending balance (shares) at Dec. 31, 2020	13,169,204	0
Ending balance, amount at Dec. 31, 2020	$ 13	$ 0	$ 366,087	$ (349,765)	$ 16,335