CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Common Stock	Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2020		128,138,311,000
Beginning balance at Dec. 31, 2020	$ 146,379	$ 1,282	$ 643,269	$ 0	$ (498,172)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock, net of issuance costs (in shares)		68,170,579,000
Issuance of common stock, net of issuance costs	457,483	$ 682	456,801
Issuance of common stock upon exercise of warrants (in shares)		1,866,758,000
Issuance of common stock upon exercise of warrants	1,121	$ 18	1,103
Non-cash stock-based compensation	3,300		3,300
Issuance of common stock under stock plans, net of taxes ( in shares)		3,704,330,000
Issuance of common stock under stock plans, net of taxes	(5,497)	$ 37	(5,534)
Other comprehensive loss	(296)			(296)
Net loss	(42,690)				(42,690)
Ending balance (in shares) at Sep. 30, 2021		201,879,978,000
Ending balance at Sep. 30, 2021	559,800	$ 2,019	1,098,939	(296)	(540,862)
Beginning balance (in shares) at Jun. 30, 2021		197,964,476,000
Beginning balance at Jun. 30, 2021	576,123	$ 1,980	1,100,932	(307)	(526,482)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock warrants, net of issuance costs	(162)		(162)
Non-cash stock-based compensation	1,880		1,880
Issuance of common stock under stock plans, net of taxes ( in shares)		3,915,502,000
Issuance of common stock under stock plans, net of taxes	(3,672)	$ 39	(3,711)
Other comprehensive loss	11			11
Net loss	(14,380)				(14,380)
Ending balance (in shares) at Sep. 30, 2021		201,879,978,000
Ending balance at Sep. 30, 2021	$ 559,800	$ 2,019	1,098,939	(296)	(540,862)
Beginning balance (in shares) at Dec. 31, 2021	201,988,662	201,988,662,000
Beginning balance at Dec. 31, 2021	$ 547,255	$ 2,020	1,103,224	(614)	(557,375)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock and common stock warrants, net of issue costs (in shares)		33,333,336,000
Issuance of common stock and common stock warrants, net of issuance costs	139,008	$ 333	138,675
Issuance of common stock upon exercise of warrants (in shares)		4,677,000
Issuance of common stock upon exercise of warrants	3		3
Non-cash stock-based compensation	12,625		12,625
Issuance of common stock under stock plans, net of taxes ( in shares)		1,895,057,000
Issuance of common stock under stock plans, net of taxes	225	$ 19	206
Other comprehensive loss	(1,554)			(1,554)
Net loss	$ (72,620)				(72,620)
Ending balance (in shares) at Sep. 30, 2022	237,221,732	237,221,732,000
Ending balance at Sep. 30, 2022	$ 624,942	$ 2,372	1,254,733	(2,168)	(629,995)
Beginning balance (in shares) at Jun. 30, 2022		235,165,951,000
Beginning balance at Jun. 30, 2022	663,768	$ 2,353	1,249,880	(2,256)	(586,209)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Non-cash stock-based compensation	4,361		4,361
Issuance of common stock under stock plans, net of taxes ( in shares)		2,055,781,000
Issuance of common stock under stock plans, net of taxes	511	$ 19	492
Other comprehensive loss	88			88
Net loss	$ (43,786)				(43,786)
Ending balance (in shares) at Sep. 30, 2022	237,221,732	237,221,732,000
Ending balance at Sep. 30, 2022	$ 624,942	$ 2,372	$ 1,254,733	$ (2,168)	$ (629,995)