Condensed Consolidated Statements of Stockholders' (Deficit) Equity - USD ($) shares in Thousands, $ in Thousands	Total	Convertible Preferred Stock	At-the-Market Offering	Common Stock	Common Stock At-the-Market Offering	Additional Paid-In Capital	Additional Paid-In Capital At-the-Market Offering	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance at Dec. 31, 2020	$ 102,371			$ 7		$ 478,599		$ (376,238)	$ 3
Balance, shares at Dec. 31, 2020				70,686
Issuance of common stock			$ 9,488				$ 9,488
Issuance of common stock, shares					3,197
Exercise of stock options	2					2
Exercise of stock options, shares				1
Stock-based compensation expense	2,695					2,695
Net loss	(20,395)							(20,395)
Unrealized gain (loss) on available-for-sale securities	(3)								(3)
Balance at Mar. 31, 2021	94,158			$ 7		490,784		(396,633)
Balance, shares at Mar. 31, 2021				73,884
Balance at Dec. 31, 2020	102,371			$ 7		478,599		(376,238)	$ 3
Balance, shares at Dec. 31, 2020				70,686
Net loss	(115,100)
Balance at Dec. 31, 2021	8,382			$ 8		499,700		(491,326)
Balance, shares at Dec. 31, 2021				77,144
Temporary equity, Balance at Dec. 31, 2021	$ 40,702	$ 40,702
Temporary equity, Balance, shares at Dec. 31, 2021	1,000	1,000
Issuance of common stock			$ 1,137				$ 1,137
Issuance of common stock, shares					1,234
Issuance of common stock pursuant to equity incentive plans, Shares				340
Stock-based compensation expense	$ 1,180					1,180
Net loss	(13,835)							(13,835)
Balance at Mar. 31, 2022	(3,136)			$ 8		$ 502,017		$ (505,161)
Balance, shares at Mar. 31, 2022				78,718
Temporary equity, Balance at Mar. 31, 2022	$ 40,702	$ 40,702
Temporary equity, Balance, shares at Mar. 31, 2022	1,000	1,000