CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Balance at Dec. 31, 2020	$ 240,578	$ 34	$ 742,387	$ (270)	$ (501,573)
Balance (in shares) at Dec. 31, 2020		34,026,680
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs	34,137	$ 6	34,131
Issuance of common stock under at-the-market (ATM) equity offering program, net of issuance costs (share)		5,991,858
Issuance of shares of common stock for settlement of restricted stock units (RSUs) (in shares)		86,146
Unrealized loss on marketable debt securities	(1)			(1)
Stock-based compensation	(270)		(270)
Net loss	(27,200)				(27,200)
Balance at Mar. 31, 2021	247,244	$ 40	776,248	(271)	(528,773)
Balance (in shares) at Mar. 31, 2021		40,104,684
Balance at Dec. 31, 2021	168,929	$ 48	800,728	(419)	(631,428)
Balance (in shares) at Dec. 31, 2021		48,120,437
Issuance of shares of common stock for settlement of restricted stock units (RSUs) (in shares)		12,500
Unrealized loss on marketable debt securities	(489)			(489)
Stock-based compensation	1,442		1,442
Net loss	(23,091)				(23,091)
Balance at Mar. 31, 2022	$ 146,791	$ 48	$ 802,170	$ (908)	$ (654,519)
Balance (in shares) at Mar. 31, 2022		48,132,937