Condensed Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Unaudited) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Series B Convertible Preferred Stock	Common Stock	Additional Paid-in Capital	Accumulated Deficit
Balance at Sep. 20, 2019	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Convertible preferred stock balance, shares at Sep. 20, 2019		0	0
Balance, shares at Sep. 20, 2019				0
Issuance of Founders Shares, shares				8,715,999
Net loss	(31)					(31)
Balance at Sep. 30, 2019	(31)	$ 0	$ 0	$ 0	0	(31)
Convertible preferred stock balance, shares at Sep. 30, 2019		0	0
Balance, shares at Sep. 30, 2019				8,715,999
Balance at Dec. 31, 2019	$ (135)				980	(1,115)
Balance, shares at Dec. 31, 2019	10,894,999			10,894,999
Issuance of convertible preferred stock		$ 28,345	$ 95,815
Issuance of convertible preferred stock, shares		10,000,000	5,647,048
Reclassification of preferred stock tranche liability upon issuance of Series A milestone shares		$ 18,080
Conversion of Series A and Series B convertible preferred stock to common stock		$ (46,425)	$ (95,815)
Conversion of Series A and Series B convertible preferred stock to common stock, shares		(10,000,000)	(5,647,048)
Conversion of Series A and Series B convertible preferred stock to common stock	$ 142,240				142,240
Conversion of convertible to common stock, shares				17,047,378
Issuance of shares of common stock	165,889				165,889
Issuance of shares of common stock, shares				9,050,000
Issuance of restricted stock award, shares				769,058
Stock-based compensation	1,341				1,341
Net loss	(41,693)					(41,693)
Balance at Sep. 30, 2020	$ 267,642				310,450	(42,808)
Balance, shares at Sep. 30, 2020	37,761,435			37,761,435
Balance at Jun. 30, 2020	$ (26,786)				980	(27,766)
Convertible preferred stock balance, shares at Jun. 30, 2020		6,200,000
Convertible preferred stock balance at Jun. 30, 2020		$ 18,014
Balance, shares at Jun. 30, 2020				10,894,999
Issuance of convertible preferred stock		$ 11,235	$ 95,815
Issuance of convertible preferred stock, shares		3,800,000	5,647,048
Reclassification of preferred stock tranche liability upon issuance of Series A milestone shares		$ 17,176
Conversion of Series A and Series B convertible preferred stock to common stock		$ (46,425)	$ (95,815)
Conversion of Series A and Series B convertible preferred stock to common stock, shares		(10,000,000)	(5,647,048)
Conversion of Series A and Series B convertible preferred stock to common stock	142,240				142,240
Conversion of convertible to common stock, shares				17,047,378
Issuance of shares of common stock	165,889				165,889
Issuance of shares of common stock, shares				9,050,000
Issuance of restricted stock award, shares				769,058
Stock-based compensation	1,341				1,341
Net loss	(15,042)					(15,042)
Balance at Sep. 30, 2020	$ 267,642				$ 310,450	$ (42,808)
Balance, shares at Sep. 30, 2020	37,761,435			37,761,435