Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common stock	Additional paid-in capital	Accumulated deficit	Series A	Series B	Series C
Beginning balance (in shares) at Dec. 31, 2017	12,501,503
Beginning balance at Dec. 31, 2017	$ 12,458
Convertible preferred stock
Issuance of convertible preferred stock, net (in shares)					10,000,000	11,166,572
Issuance of convertible preferred stock, net					$ 9,899	$ 38,413
Ending balance (in shares) at Dec. 31, 2018	33,668,075				22,501,503	11,166,572
Ending balance at Dec. 31, 2018	$ 60,770				$ 22,357	$ 38,413
Beginning balance (in shares) at Dec. 31, 2017		2,081,187
Beginning balance at Dec. 31, 2017	(6,675)	$ 1	$ 105	$ (6,781)
Common stock
Grant of restricted common stock awards (in shares)		92,497
Grant of restricted common stock awards	0
Stock-based compensation	64		64
Net loss	$ (8,931)			(8,931)
Ending balance (in shares) at Dec. 31, 2018	2,173,684	2,173,684
Ending balance at Dec. 31, 2018	$ (15,542)	$ 1	169	(15,712)
Convertible preferred stock
Issuance of convertible preferred stock, net (in shares)						11,751,154	19,420,124
Issuance of convertible preferred stock, net						$ 55,066	$ 84,737
Ending balance (in shares) at Dec. 31, 2019	64,839,353				22,501,503	22,917,726	19,420,124
Ending balance at Dec. 31, 2019	$ 200,573				$ 22,357	$ 93,479	$ 84,737
Common stock
Grant of restricted common stock awards (in shares)		62,988
Grant of restricted common stock awards	0
Stock-based compensation	3,643		3,643
Net loss	$ (35,258)			(35,258)
Ending balance (in shares) at Dec. 31, 2019	2,236,672	2,236,672
Ending balance at Dec. 31, 2019	$ (47,157)	$ 1	$ 3,812	$ (50,970)