Organization and Description of Business - Additional Information (Details) $ / shares in Units, $ in Thousands			3 Months Ended	9 Months Ended
	Jul. 14, 2020 USD ($) $ / shares shares	Jul. 01, 2020 USD ($) shares	Sep. 30, 2020 USD ($) shares	Sep. 30, 2020 USD ($) Segment shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($) shares
Class Of Stock [Line Items]
Number of operating segments | Segment				1
Shares issued during period | shares			32,568,332	32,568,332		1,600,601
Proceeds from initial public offering, net of issuance costs				$ 265,461
Accumulated deficit			$ 100,124	100,124		$ 26,660
Cash, cash equivalents restricted cash and short-term investments			$ 330,200	$ 330,200
Proceeds from issuance of convertible notes, net of issuance costs					$ 5,986
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Proceeds from issuance of convertible notes, net of issuance costs		$ 64,400
Temporary equity, shares issued | shares		27,066,206
IPO
Class Of Stock [Line Items]
Shares issued during period | shares	16,100,000
Shares issued, price per share | $ / shares	$ 18.00
Proceeds from initial public offering, net of issuance costs	$ 265,100	$ 265,100
Underwriters Option to Purchase Additional Shares
Class Of Stock [Line Items]
Shares issued during period | shares	2,100,000
Common Stock
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock, Shares | shares			14,689,215
Common Stock | IPO
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock, Shares | shares	14,689,215
Proceeds from initial public offering, net of issuance costs	$ 265,100