Consolidated Balance Sheet Components - Schedule of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Total property and equipment	$ 24,324	$ 17,342
Accumulated depreciation and amortization	(11,517)	(7,814)
Property and equipment, net	12,807	9,528
Computer and Equipment
Property Plant And Equipment [Line Items]
Total property and equipment	10,982	8,787
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment	7,134	4,201
Website and Internal-Use Software
Property Plant And Equipment [Line Items]
Total property and equipment	4,384	2,902
Office Equipment and Furniture
Property Plant And Equipment [Line Items]
Total property and equipment	$ 1,824	$ 1,452