Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	At The Market Facility Member	Common Stock [Member]	Common Stock [Member] At The Market Facility Member	Additional Paid-in Capital [Member]	Additional Paid-in Capital [Member] At The Market Facility Member	Accumulated Deficit [Member]
Beginning balance at Dec. 31, 2020	$ 254,344		$ 4		$ 518,756		$ (264,416)
Beginning balance, shares at Dec. 31, 2020			41,569,000
Stock-based compensation expense	14,494				14,494
Exercise of stock options, shares			206,000
Exercise of stock options	872				872
Issuance of common stock under ATM facility, net of offering costs of $67, shares				1,829,000
Issuance of common stock under ATM facility, net of offering costs of $67		$ 14,550				$ 14,550
Issuance of common stock under 2018 employee stock purchase plan	208				208
Issuance of common stock under 2018 employee stock purchase plan, shares			28,000
Net loss	(90,899)						(90,899)
Ending balance at Sep. 30, 2021	193,569		$ 4		548,880		(355,315)
Ending balance, shares at Sep. 30, 2021			43,632,000
Beginning balance at Jun. 30, 2021	220,992		$ 4		543,690		(322,702)
Beginning balance, shares at Jun. 30, 2021			43,623,000
Stock-based compensation expense	5,168				5,168
Exercise of stock options, shares			9,000
Exercise of stock options	22				22
Net loss	(32,613)						(32,613)
Ending balance at Sep. 30, 2021	193,569		$ 4		548,880		(355,315)
Ending balance, shares at Sep. 30, 2021			43,632,000
Beginning balance at Dec. 31, 2021	169,476		$ 4		553,014		(383,542)
Beginning balance, shares at Dec. 31, 2021			43,652,000
Stock-based compensation expense	$ 9,267				9,267
Exercise of stock options, shares	0
Issuance of common stock under 2018 employee stock purchase plan	$ 203				203
Issuance of common stock under 2018 employee stock purchase plan, shares			121,000
Net loss	(80,856)						(80,856)
Ending balance at Sep. 30, 2022	98,090		$ 4		562,484		(464,398)
Ending balance, shares at Sep. 30, 2022			43,773,000
Beginning balance at Jun. 30, 2022	118,343		$ 4		559,768		(441,429)
Beginning balance, shares at Jun. 30, 2022			43,696,000
Stock-based compensation expense	2,656				2,656
Issuance of common stock under 2018 employee stock purchase plan	60				60
Issuance of common stock under 2018 employee stock purchase plan, shares			77,000
Net loss	(22,969)						(22,969)
Ending balance at Sep. 30, 2022	$ 98,090		$ 4		$ 562,484		$ (464,398)
Ending balance, shares at Sep. 30, 2022			43,773,000