Balance Sheet Details - 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	$ 6,370	$ 6,373
Less: accumulated depreciation and amortization	(3,831)	(2,982)
Property and equipment, net	2,539	3,391
Furniture and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	397	397
Computers and Computer Software
Property Plant And Equipment [Line Items]
Total property and equipment	169	146
Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	3,887	3,260
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	1,903	1,884
Capital Leases — Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment		686
Less: accumulated depreciation and amortization		(471)
Property and equipment, net		$ 215
Construction in Progress
Property Plant And Equipment [Line Items]
Total property and equipment	$ 14