Condensed Consolidated Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total	$ 19,841	$ 18,750
Less: Accumulated depreciation and amortization	(9,479)	(7,643)
Property and equipment, net	10,362	11,107	[1]
Scientific Equipment
Property Plant And Equipment [Line Items]
Total	7,536	6,628
Furniture and Equipment
Property Plant And Equipment [Line Items]
Total	1,040	813
Capitalized Software
Property Plant And Equipment [Line Items]
Total	146	146
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total	10,834	10,828
Construction in Progress
Property Plant And Equipment [Line Items]
Total	$ 285	$ 335

[1] The Condensed Consolidated Balance Sheet as of December 31, 2018 has been derived from the audited financial statements as of that date.