Nature of Business - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		9 Months Ended
	Nov. 03, 2020	Nov. 30, 2020	Oct. 31, 2020	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Nature of Business [Line Items]
Shares issued				48,958,829	33,645,447
Gross proceeds from issuance of preferred stock				$ 106,631
Convertible preferred stock converted into shares				48,958,829
Accumulated deficit				$ 85,816	$ 54,213
Cash and cash equivalents				$ 105,383	$ 21,661	$ 25,604
Subsequent Event | IPO
Nature of Business [Line Items]
Share price	$ 24.00	$ 24.00
Aggregated gross proceeds from initial public offering ("IPO")	$ 345,000	$ 345,000
Underwriting discounts and commissions	24,150	24,150
Offering expenses	$ 3,200	$ 3,200
Subsequent Event | IPO | Common Stock
Nature of Business [Line Items]
Shares issued	14,375,000	14,375,000
Subsequent Event | Over-Allotment Option | Maximum
Nature of Business [Line Items]
Shares issued	1,875,000	1,875,000
Subsequent Event | Roche License Agreement
Nature of Business [Line Items]
Upfront payment received		$ 350,000
Series D-1 Convertible Preferred Stock | Subsequent Event
Nature of Business [Line Items]
Shares issued			8,973,261
Share price			$ 11.98
Gross proceeds from issuance of preferred stock			$ 107,500
Series A, B, C, D and D-1 Convertible Preferred Stock | Subsequent Event | IPO | Common Stock
Nature of Business [Line Items]
Convertible preferred stock converted into shares	57,932,090	57,932,090