Balance Sheet Accounts and Supplemental Disclosures - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Dec. 31, 2019
Property Plant And Equipment [Line Items]
Total property and equipment	$ 7,650	$ 6,639
Less: accumulated depreciation	1,893	1,214
Property and equipment, net	5,757	5,425
Office Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,097	1,097
Office Equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	3 years
Office Equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	7 years
Computer Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 143	124
Property and equipment, estimated useful life	5 years
Software
Property Plant And Equipment [Line Items]
Total property and equipment	$ 114	87
Property and equipment, estimated useful life	3 years
Lab Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	$ 3,765	3,054
Lab Equipment | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	2 years
Lab Equipment | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	5 years
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	$ 2,474	2,229
Leasehold Improvements | Minimum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	6 years
Leasehold Improvements | Maximum
Property Plant And Equipment [Line Items]
Property and equipment, estimated useful life	7 years
Construction in Process
Property Plant And Equipment [Line Items]
Total property and equipment	$ 57	$ 48