CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Series A Preferred Stock Preferred Stock	Common Stock	Additional Paid-in Capital	Treasury Stock	Accumulated Deficit	Total
Balance at Dec. 31, 2020	$ 4,469	$ 37	$ 444,622		$ (311,929)	$ 137,199
Balance (in shares) at Dec. 31, 2020	4,753	36,578,460		7,307
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation expense			5,035			5,035
Exercise of stock options			244			244
Exercise of stock options (in shares)		55,030
Financing costs			(3)			(3)
Net loss					(27,141)	(27,141)
Balance at Mar. 31, 2021	$ 4,469	$ 37	449,898		(339,070)	115,334
Balance (in shares) at Mar. 31, 2021	4,753	36,633,490		7,307
Balance at Dec. 31, 2021	$ 4,302	$ 37	459,852		(410,705)	53,486
Balance (in shares) at Dec. 31, 2021	4,575	36,790,254		7,307
Increase (Decrease) in Stockholders' Equity (Deficit)
Stock-based compensation expense			3,379			3,379
Exercise of stock options			1,733			1,733
Exercise of stock options (in shares)		225,165
Issuance of common stock			1,168			1,168
Issuance of common stock (in shares)		123,255
Net loss					(19,361)	(19,361)
Balance at Mar. 31, 2022	$ 4,302	$ 37	$ 466,132		$ (430,066)	$ 40,405
Balance (in shares) at Mar. 31, 2022	4,575	37,138,674		7,307