CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2020	$ 103,891	$ 502,217	$ (95)	$ (398,231)
Balance, Shares at Dec. 31, 2020		27,175,305
Issuance of common stock upon the exercise of common stock options	372	$ 372
Issuance of common stock upon the exercise of common stock options, Shares		287,705
Issuance of common stock in connection with employee stock purchase plan	211	$ 211
Issuance of common stock in connection with employee stock purchase plan , Shares		14,951
Stock-based compensation expense	1,112	$ 1,112
Foreign currency translation adjustment	(2)		(2)
Unrealized gains (losses) on marketable securities	8		8
Net loss	(7,917)			(7,917)
Balance at Mar. 31, 2021	97,675	$ 503,912	(89)	(406,148)
Balance, Shares at Mar. 31, 2021		27,477,961
Balance at Dec. 31, 2020	103,891	$ 502,217	(95)	(398,231)
Balance, Shares at Dec. 31, 2020		27,175,305
Net loss	(44,200)
Balance at Dec. 31, 2021	67,854	$ 510,488	(188)	(442,446)
Balance, Shares at Dec. 31, 2021		27,791,615
Issuance of common stock upon the exercise of common stock options	202	$ 202
Issuance of common stock upon the exercise of common stock options, Shares		164,503
Issuance of common stock in connection with employee stock purchase plan	203	$ 203
Issuance of common stock in connection with employee stock purchase plan , Shares		12,465
Stock-based compensation expense	2,310	$ 2,310
Foreign currency translation adjustment	(24)		(24)
Unrealized gains (losses) on marketable securities	(73)		(73)
Net loss	(10,562)			(10,562)
Balance at Mar. 31, 2022	$ 59,910	$ 513,203	$ (285)	$ (453,008)
Balance, Shares at Mar. 31, 2022		27,968,583