Preferred Stock - Additional Information (Details) - USD ($)		9 Months Ended
	Jul. 05, 2019	Sep. 30, 2020	Dec. 31, 2019	Jul. 22, 2019
Temporary Equity [Line Items]
Preferred stock, shares authorized		5,000,000	5,000,000	5,000,000
Preferred stock, shares issued		0	0
Preferred stock, shares outstanding		0	0
Gross proceeds threshold of automatic conversion of preferred stock eliminated	$ 45,000,000
IPO | Common Stock
Temporary Equity [Line Items]
Number of preferred stock converted into common stock				16,071,418
Series B Preferred Stock
Temporary Equity [Line Items]
Temporary equity, dividends declared		$ 0
Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, share outstanding				112,500,000
Series A Preferred Stock
Temporary Equity [Line Items]
Temporary equity, dividends declared		$ 0
GSK Agreement | Series B Preferred Stock
Temporary Equity [Line Items]
Issuance of convertible preferred stock		12,500,000