Balance Sheet Components - Schedule of Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Personnel expenses	$ 1,846	$ 1,261
Professional fees	224	96
Research and development expenses	9,751	4,410
Other	279	50
Total accrued expenses and other current liabilities	$ 12,100	$ 5,817