Balance Sheet Components - Summary of Property and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Property and equipment	$ 5,624	$ 4,824
Less: Accumulated depreciation and amortization	(2,895)	(2,080)
Property and equipment, net	2,729	2,744
Scientific Equipment
Property Plant And Equipment [Line Items]
Property and equipment	4,597	3,995
Furniture and Equipment
Property Plant And Equipment [Line Items]
Property and equipment	488	301
Capitalized Software
Property Plant And Equipment [Line Items]
Property and equipment	231	225
Leasehold Improvements
Property Plant And Equipment [Line Items]
Property and equipment	$ 308	$ 303