Balance Sheet Details - Schedule of Accrued Expenses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Accrued Liabilities Current [Abstract]
Accrued R&D expenses	$ 13,361	$ 384
Accrued compensation expenses	2,468	1,052
Accrued professional & consulting expenses	762	478
Accrued other	2	405
Total accrued expenses	$ 16,593	$ 2,319