Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 10,328	$ 3,725
Less accumulated depreciation and amortization	(1,148)	(645)
Total property and equipment, net	9,180	3,080
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	3,992	287
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment	322	265
Research Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	3,839	2,929
Computers and Software
Property Plant And Equipment [Line Items]
Total property and equipment	95	61
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 2,080	$ 183