Condensed Statements of Convertible Preferred Stock/Units and Stockholders'/Members' Equity (Deficit) - USD ($) $ in Thousands	Total	IPO	Preferred Units	Common Units	Predecessor's Deficit	Convertible Preferred Stock	Common Stock	Common Stock IPO	Additional Paid-in Capital	Additional Paid-in Capital IPO	Accumulated Deficit	Accumulated Deficit IPO
Balance at Dec. 31, 2018	$ (41,129)				$ (41,555)		$ 0		$ 0		$ 0
Preferred Units, balance, Units at Dec. 31, 2018			12,459,000
Preferred Units, balance at Dec. 31, 2018			$ 32,693
Temporary equity, balance, Shares at Dec. 31, 2018						0
Temporary equity, balance at Dec. 31, 2018						$ 0
Members' equity, balance, Units at Dec. 31, 2018				2,842,000
Members' equity, balance at Dec. 31, 2018				$ 426
Balance, Shares at Dec. 31, 2018							0
Distribution to members			(106)
Issuance of common units upon exercise of unit options	39		0	$ 39	0	0	$ 0		0		0
Issuance of common units upon exercise of unit options, Units				78,000
Vesting of early exercise options	5		0	$ 5	0	0	0		0		0
Stock-based compensation	17			17	0		0		0		0
Net loss	(2,549)		$ 0	$ 0	(2,549)	$ 0	0		0		0
Balance at Mar. 31, 2019	(43,617)				(44,104)		$ 0		0		0
Preferred Units, balance, Units at Mar. 31, 2019			12,459,000
Preferred Units, balance at Mar. 31, 2019			$ 32,587
Temporary equity, balance, Shares at Mar. 31, 2019						0
Temporary equity, balance at Mar. 31, 2019						$ 0
Members' equity, balance, Units at Mar. 31, 2019				2,920,000
Members' equity, balance at Mar. 31, 2019				$ 487
Balance, Shares at Mar. 31, 2019							0
Balance at Dec. 31, 2018	(41,129)				(41,555)		$ 0		0		0
Preferred Units, balance, Units at Dec. 31, 2018			12,459,000
Preferred Units, balance at Dec. 31, 2018			$ 32,693
Temporary equity, balance, Shares at Dec. 31, 2018						0
Temporary equity, balance at Dec. 31, 2018						$ 0
Members' equity, balance, Units at Dec. 31, 2018				2,842,000
Members' equity, balance at Dec. 31, 2018				$ 426
Balance, Shares at Dec. 31, 2018							0
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	0
Net loss	(14,333)
Balance at Sep. 30, 2019	(55,326)				0		$ 0		(43,542)		(11,784)
Preferred Units, balance, Units at Sep. 30, 2019			0
Preferred Units, balance at Sep. 30, 2019			$ 0
Temporary equity, balance, Shares at Sep. 30, 2019						12,459,000
Temporary equity, balance at Sep. 30, 2019						$ 32,587
Members' equity, balance, Units at Sep. 30, 2019				0
Members' equity, balance at Sep. 30, 2019				$ 0
Balance, Shares at Sep. 30, 2019							2,975,000
Balance at Mar. 31, 2019	(43,617)				(44,104)		$ 0		0		0
Preferred Units, balance, Units at Mar. 31, 2019			12,459,000
Preferred Units, balance at Mar. 31, 2019			$ 32,587
Temporary equity, balance, Shares at Mar. 31, 2019						0
Temporary equity, balance at Mar. 31, 2019						$ 0
Members' equity, balance, Units at Mar. 31, 2019				2,920,000
Members' equity, balance at Mar. 31, 2019				$ 487
Balance, Shares at Mar. 31, 2019							0
Conversion from LLC to C corporation	0			$ (487)	44,104		$ 0		(43,617)		0
Conversion from LLC to C corporation, Temporary equity, Shares			(12,459,000)			12,459,000
Conversion from LLC to C corporation, Temporary equity			$ (32,587)			$ 32,587
Conversion from LLC to C corporation, Shares				(2,920,000)			2,920,000
Issuance of common stock upon exercise of stock options, net of repurchases	3		0	$ 0	0	0	$ 0		3		0
Issuance of common stock upon exercise of stock options, net of repurchases, Shares							7,000
Vesting of early exercise options	16		0	0	0	0	$ 0		16		0
Stock-based compensation	16			0	0		0		16		0
Net loss	(5,116)		$ 0	$ 0	0	$ 0	0		0		(5,116)
Balance at Jun. 30, 2019	(48,698)				0		$ 0		(43,582)		(5,116)
Preferred Units, balance, Units at Jun. 30, 2019			0
Preferred Units, balance at Jun. 30, 2019			$ 0
Temporary equity, balance, Shares at Jun. 30, 2019						12,459,000
Temporary equity, balance at Jun. 30, 2019						$ 32,587
Members' equity, balance, Units at Jun. 30, 2019				0
Members' equity, balance at Jun. 30, 2019				$ 0
Balance, Shares at Jun. 30, 2019							2,927,000
Issuance of common stock upon exercise of stock options	16		0	0	0	0	$ 0		16		0
Issuance of common stock upon exercise of stock options, Shares							48,000
Vesting of early exercise options	2		0	0	0	0	$ 0		2		0
Stock-based compensation	22			0	0		0		22		0
Net loss	(6,668)		$ 0	$ 0	0	$ 0	0		0		(6,668)
Balance at Sep. 30, 2019	(55,326)				$ 0		$ 0		(43,542)		(11,784)
Preferred Units, balance, Units at Sep. 30, 2019			0
Preferred Units, balance at Sep. 30, 2019			$ 0
Temporary equity, balance, Shares at Sep. 30, 2019						12,459,000
Temporary equity, balance at Sep. 30, 2019						$ 32,587
Members' equity, balance, Units at Sep. 30, 2019				0
Members' equity, balance at Sep. 30, 2019				$ 0
Balance, Shares at Sep. 30, 2019							2,975,000
Balance at Dec. 31, 2019	$ (65,357)						$ 0		(43,172)		(22,185)
Temporary equity, balance, Shares at Dec. 31, 2019	37,267,000					37,267,000
Temporary equity, balance at Dec. 31, 2019	$ 134,720					$ 134,720
Balance, Shares at Dec. 31, 2019							2,989,000
Issuance of common stock upon exercise of stock options, net of repurchases	16					0	$ 0		16		0
Issuance of common stock upon exercise of stock options, net of repurchases, Shares							41,000
Vesting of early exercise options	14					0	$ 0		14		0
Issuance of convertible preferred stock, net of issuance costs						$ 2,200
Issuance of convertible preferred stock, net of issuance costs, Shares						538,000
Stock-based compensation	449						0		449		0
Net loss	(6,085)					$ 0	0		0		(6,085)
Balance at Mar. 31, 2020	(70,963)						$ 0		(42,693)		(28,270)
Temporary equity, balance, Shares at Mar. 31, 2020						37,805,000
Temporary equity, balance at Mar. 31, 2020						$ 136,920
Balance, Shares at Mar. 31, 2020							3,030,000
Balance at Dec. 31, 2019	$ (65,357)						$ 0		(43,172)		(22,185)
Temporary equity, balance, Shares at Dec. 31, 2019	37,267,000					37,267,000
Temporary equity, balance at Dec. 31, 2019	$ 134,720					$ 134,720
Balance, Shares at Dec. 31, 2019							2,989,000
Issuance of common stock upon exercise of stock options, Shares	106,000
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	$ 120
Net loss	(28,080)
Balance at Sep. 30, 2020	$ 320,164						$ 4		370,425		(50,265)
Temporary equity, balance, Shares at Sep. 30, 2020	0					0
Temporary equity, balance at Sep. 30, 2020	$ 0					$ 0
Balance, Shares at Sep. 30, 2020							37,527,000
Balance at Mar. 31, 2020	(70,963)						$ 0		(42,693)		(28,270)
Temporary equity, balance, Shares at Mar. 31, 2020						37,805,000
Temporary equity, balance at Mar. 31, 2020						$ 136,920
Balance, Shares at Mar. 31, 2020							3,030,000
Vesting of early exercise options	34					0	$ 0		34		0
Issuance of stock, net of issuance costs, Value		$ 274,054						$ 2		$ 274,052		$ 0
Issuance of stock, net of issuance costs, Shares								16,560,000
Conversion of convertible preferred stock into common stock upon completion of initial public offering	136,920					$ (136,920)	$ 2		136,918		0
Conversion of convertible preferred stock into common stock upon completion of initial public offering, Shares						(37,805,000)	17,921,000
Reclassification of warrant liability to equity due to adjustment from preferred stock warrant to common stock warrant upon completion of initial public offering	120					$ 0	$ 0		120		0
Cashless exercise of common stock warrants	0						$ 0		0		0
Cashless exercise of common stock warrants, Shares							16,000
Stock-based compensation	687						$ 0		687		0
Net loss	(10,556)					$ 0	0		0		(10,556)
Balance at Jun. 30, 2020	330,296						$ 4		369,118		(38,826)
Temporary equity, balance, Shares at Jun. 30, 2020						0
Temporary equity, balance at Jun. 30, 2020						$ 0
Balance, Shares at Jun. 30, 2020							37,527,000
Vesting of early exercise options	11					0	$ 0		11		0
Stock-based compensation	1,296					0	0		1,296		0
Net loss	(11,439)					$ 0	0		0		(11,439)
Balance at Sep. 30, 2020	$ 320,164						$ 4		$ 370,425		$ (50,265)
Temporary equity, balance, Shares at Sep. 30, 2020	0					0
Temporary equity, balance at Sep. 30, 2020	$ 0					$ 0
Balance, Shares at Sep. 30, 2020							37,527,000