Condensed Consolidated Balance Sheet Components - Summary of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Property Plant And Equipment [Line Items]
Total	$ 19,622	$ 18,750
Less: Accumulated depreciation and amortization	(8,596)	(7,643)
Property and equipment, net	11,026	11,107	[1]
Scientific Equipment
Property Plant And Equipment [Line Items]
Total	7,400	6,628
Furniture and Equipment
Property Plant And Equipment [Line Items]
Total	862	813
Capitalized Software
Property Plant And Equipment [Line Items]
Total	146	146
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total	10,828	10,828
Construction in Progress
Property Plant And Equipment [Line Items]
Total	$ 386	$ 335

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