Balance Sheet Components - Components of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 34,096	$ 14,388
Less: accumulated depreciation and amortization	(7,632)	(5,230)
Total property and equipment, net	26,464	9,158
Laboratory and manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	4,238	2,750
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,315	1,062
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	3,669	925
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	7,597	726
Internal-use software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 16,277	$ 8,925