Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Unrealized Gain/(Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		148,074,085
Beginning balance at Dec. 31, 2020	$ 247,618	$ 1	$ 1,425,115	$ 13	$ (1,177,511)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs (in shares)		9,228,017
Issuance of common stock, net of    issuance costs	29,498	$ 1	29,497
Proceeds from sale of stock under employee stock purchase plan (in shares)		154,276
Proceeds from sale of stock under    employee stock purchase plan	367		367
Share-based compensation expense	5,992		5,992
Restricted stock unit vesting (in shares)		1,063,711
Unrealized loss	(4)			(4)
Net loss	(69,580)				(69,580)
Ending balance (in shares) at Mar. 31, 2021		158,520,089
Ending balance at Mar. 31, 2021	$ 213,891	$ 2	1,460,971	9	(1,247,091)
Beginning balance (in shares) at Dec. 31, 2021	177,000,963	177,000,963
Beginning balance at Dec. 31, 2021	$ 76,456	$ 1	1,536,800	6	(1,460,351)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs (in shares)		4,404,600
Issuance of common stock, net of    issuance costs	7,178	$ 1	7,177
Proceeds from sale of stock under employee stock purchase plan (in shares)		191,146
Proceeds from sale of stock under    employee stock purchase plan	367		367
Share-based compensation expense	4,536		4,536
Restricted stock unit vesting (in shares)		1,789,326
Unrealized loss	0
Net loss	$ (62,421)				(62,421)
Ending balance (in shares) at Mar. 31, 2022	183,386,035	183,386,035
Ending balance at Mar. 31, 2022	$ 26,116	$ 2	$ 1,548,880	$ 6	$ (1,522,772)