Accrued Expenses and Other Liabilities - Schedule of Accrued Expenses and Other Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Payables And Accruals [Abstract]
Accrued compensation and benefits	$ 5,641	$ 4,551
Accrued research and development expenses	1,997	2,258
Accrued professional fees	461	542
Accrued unvested common stock subject to repurchase	16	37
Accrued other	311	256
Total accrued expenses and other liabilities	$ 8,426	$ 7,644