Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Accumulated other comprehensive loss	Accumulated Deficit
Beginning balance at Dec. 31, 2019	$ 87,153	$ 23		$ 237,931		$ (150,801)
Beginning balance, Shares at Dec. 31, 2019		22,654,444
Issuance of common stock under employee benefit plans	286			286
Issuance of common stock under employee benefit plans, Shares		36,472
Vesting of restricted stock awards	4			4
Vesting of restricted stock awards, Shares		102,221
Repurchase of unvested restricted stock awards			8,787
Retirement of treasury shares			(8,787)
Stock-based compensation expense	1,693			1,693
Unrealized loss on marketable securities	(53)				$ (53)
Net loss	(18,452)					(18,452)
Ending balance at Mar. 31, 2020	70,631	$ 23		239,914	(53)	(169,253)
Ending balance, Shares at Mar. 31, 2020		22,793,137
Beginning balance at Dec. 31, 2020	95,181	$ 28		316,775	(2)	(221,620)
Beginning balance, Shares at Dec. 31, 2020		27,941,566
Issuance of common stock in connection with follow-on offering, net of issuance costs	47,407	$ 5		47,402
Issuance of common stock in connection with follow-on offering, net of issuance costs, Shares		4,600,000
Issuance of common stock under employee benefit plans	93			93
Issuance of common stock under employee benefit plans, Shares		11,888
Vesting of restricted stock awards	1			1
Vesting of restricted stock awards, Shares		40,982
Repurchase of unvested restricted stock awards			1,836
Retirement of treasury shares			(1,836)
Stock-based compensation expense	2,073			2,073
Unrealized loss on marketable securities	(2)				(2)
Net loss	(16,999)					(16,999)
Ending balance at Mar. 31, 2021	$ 127,754	$ 33		$ 366,344	$ (4)	$ (238,619)
Ending balance, Shares at Mar. 31, 2021		32,594,436