CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance (in shares) at Dec. 31, 2018		42,353,301
Balance at Dec. 31, 2018	$ 242,877	$ 424	$ 732,727	$ (490,271)	$ (3)
Share-based compensation	19,571		19,571
Issuance of common stock, net of offering costs (in shares)		6,325,000
Issuance of common stock, net of offering costs	118,657	$ 63	118,594
Stock plan related activity (in shares)		280,462
Stock plan related activity	1,315	$ 3	1,312
Unrealized gain on investments	19				19
Net loss	(151,811)			(151,811)
Balance (in shares) at Dec. 31, 2019		48,958,763
Balance at Dec. 31, 2019	230,628	$ 490	872,204	(642,082)	16
Share-based compensation	20,676		20,676
Issuance of common stock, net of offering costs (in shares)		6,612,815
Issuance of common stock, net of offering costs	170,456	$ 66	170,390
Stock plan related activity (in shares)		673,193
Stock plan related activity	3,886	$ 6	3,880
Unrealized gain on investments	(23)				(23)
Net loss	(129,739)			(129,739)
Balance (in shares) at Dec. 31, 2020		56,244,771
Balance at Dec. 31, 2020	295,884	$ 562	1,067,150	(771,821)	(7)
Share-based compensation	23,126		23,126
Issuance of common stock, net of offering costs (in shares)		4,580,653
Issuance of common stock, net of offering costs	117,818	$ 46	117,772
Stock plan related activity (in shares)		482,004
Stock plan related activity	4,959	$ 5	4,954
Unrealized gain on investments	(54)				(54)
Net loss	(202,115)			(202,115)
Balance (in shares) at Dec. 31, 2021		61,307,428
Balance at Dec. 31, 2021	$ 239,618	$ 613	$ 1,213,002	$ (973,936)	$ (61)