Balance Sheet Components - Components of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 37,612	$ 34,096
Less: accumulated depreciation and amortization	(9,158)	(7,632)
Total property and equipment, net	28,454	26,464	$ 10,278
Laboratory and manufacturing equipment
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	4,409	4,238
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,379	2,315
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	3,803	3,669
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	8,136	7,597
Internal-use software
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 18,885	$ 16,277