CONDENSED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Dec. 31, 2020		93,599,975
Beginning balance at Dec. 31, 2020	$ 126,112	$ 9	$ 680,872	$ (554,765)	$ (4)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		102,208
Issuance of common stock under employee stock purchase plan	478		478
Issuance of common stock upon exercise of options (in shares)		205,306
Issuance of common stock upon exercise of options	563		563
Issuance of common stock upon vesting of restricted stock units (in shares)		79,784
Issuance of common stock in at the market offering (in shares)		8,979,744
Issuance of common stock in at the market offering	62,446	$ 1	62,445
Stock-based compensation	6,306		6,306
Unrealized (losses) gains on available-for-sale securities	8				8
Net loss	(78,344)			(78,344)
Ending balance (in shares) at Jun. 30, 2021		102,967,017
Ending balance at Jun. 30, 2021	117,569	$ 10	750,664	(633,109)	4
Beginning balance (in shares) at Mar. 31, 2021		98,688,577
Beginning balance at Mar. 31, 2021	130,811	$ 10	718,728	(587,920)	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of options (in shares)		194,799
Issuance of common stock upon exercise of options	543		543
Issuance of common stock upon vesting of restricted stock units (in shares)		44,684
Issuance of common stock in at the market offering (in shares)		4,038,957
Issuance of common stock in at the market offering	28,174		28,174
Stock-based compensation	3,219		3,219
Unrealized (losses) gains on available-for-sale securities	11				11
Net loss	(45,189)			(45,189)
Ending balance (in shares) at Jun. 30, 2021		102,967,017
Ending balance at Jun. 30, 2021	117,569	$ 10	750,664	(633,109)	4
Beginning balance (in shares) at Dec. 31, 2021		130,182,535
Beginning balance at Dec. 31, 2021	82,617	$ 13	795,540	(712,930)	(6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock under employee stock purchase plan (in shares)		127,100
Issuance of common stock under employee stock purchase plan	$ 83		83
Issuance of common stock upon exercise of options (in shares)	0
Issuance of common stock upon vesting of restricted stock units (in shares)		2,996,142
Issuance of common stock in at the market offering (in shares)		20,492,057
Issuance of common stock in at the market offering	$ 18,478	$ 2	18,476
Stock-based compensation	6,976		6,976
Unrealized (losses) gains on available-for-sale securities	(103)				(103)
Net loss	(55,009)			(55,009)
Ending balance (in shares) at Jun. 30, 2022		153,797,834
Ending balance at Jun. 30, 2022	53,042	$ 15	821,075	(767,939)	(109)
Beginning balance (in shares) at Mar. 31, 2022		136,330,360
Beginning balance at Mar. 31, 2022	64,190	$ 14	805,265	(741,001)	(88)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon vesting of restricted stock units (in shares)		2,882,673
Issuance of common stock in at the market offering (in shares)		14,584,801
Issuance of common stock in at the market offering	12,557	$ 1	12,556
Stock-based compensation	3,254		3,254
Unrealized (losses) gains on available-for-sale securities	(21)				(21)
Net loss	(26,938)			(26,938)
Ending balance (in shares) at Jun. 30, 2022		153,797,834
Ending balance at Jun. 30, 2022	$ 53,042	$ 15	$ 821,075	$ (767,939)	$ (109)