CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit	Total
Balance at beginning of period at Dec. 31, 2018		$ 507,366	$ (69)	$ (292,173)	$ 215,124
Balance at beginning of period (in shares) at Dec. 31, 2018	41,210,725
Increase (Decrease) in Stockholders' Equity
Vesting of restricted stock units		(38)			(38)
Vesting of restricted stock units (in shares)	274,913
Unrealized gain (loss) on marketable securities			28		28
Foreign currency translation adjustment			(25)		(25)
Stock-based compensation expense		16,177			16,177
Net loss				(161,354)	(161,354)
Balance at end of period at Dec. 31, 2019		523,505	(66)	(453,527)	69,912
Balance at end of period (in shares) at Dec. 31, 2019	41,485,638
Increase (Decrease) in Stockholders' Equity
Vesting of restricted stock units		(669)			(669)
Vesting of restricted stock units (in shares)	1,390,922
Issuance of common stock in connection with public offering		7,865			7,865
Issuance of common stock in connection with public offering (in shares)	2,232,754
Unrealized gain (loss) on marketable securities		378	(2)		376
Foreign currency translation adjustment			(26)		(26)
Stock-based compensation expense		11,207			11,207
Net loss				(51,015)	(51,015)
Balance at end of period at Dec. 31, 2020		542,286	(94)	(504,542)	$ 37,650
Balance at end of period (in shares) at Dec. 31, 2020	45,109,314				45,109,314
Increase (Decrease) in Stockholders' Equity
Vesting of restricted stock units		(1,574)			$ (1,574)
Vesting of restricted stock units (in shares)	1,714,269
Issuance of common stock in connection with public offering	$ 1	238,199			238,200
Issuance of common stock in connection with public offering (in shares)	14,404,863
Unrealized gain (loss) on marketable securities			(229)		(229)
Foreign currency translation adjustment			99		99
Stock-based compensation expense		14,060			14,060
Net loss				(90,865)	(90,865)
Balance at end of period at Dec. 31, 2021	$ 1	$ 792,971	$ (224)	$ (595,407)	$ 197,341
Balance at end of period (in shares) at Dec. 31, 2021	61,228,446				61,228,446