Nature of the Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended						9 Months Ended
	Aug. 03, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019	Aug. 04, 2020	Dec. 31, 2019
Net proceeds from issuance initial public offering	$ 292,000							$ 295,449
Preferred stock, shares outstanding											59,398,350
Cash, cash equivalents, and short-term investments		$ 378,500						378,500
Net losses attributable to common stockholders		(23,614)	$ (11,632)	$ (9,339)	$ (7,270)	$ (5,302)	$ (2,524)	(44,585)	$ (15,096)
Accumulated deficit		$ (99,904)						$ (99,904)			$ (55,319)
Convertible Preferred Stock
Preferred stock, shares outstanding										0
Common Stock
Common stock issued and sold		18,687,500
Stock issued upon conversion of preferred stock		39,859,139
IPO
Common stock issued and sold	18,687,500
Public offering price per share	$ 17.00
Gross proceeds from issuance of common stock	$ 317,700
Stock issued upon conversion of preferred stock	39,859,139
IPO | Common Stock
Stock issued upon conversion of preferred stock	39,859,139