Balance Sheet Components - Components of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 59,318	$ 57,125
Less: Accumulated depreciation and amortization	(42,540)	(36,544)
Property and equipment, net	16,778	20,581	[1]
Computer Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	29,855	28,905
Software, Including Internally Developed Software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	22,720	21,323
Office Equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	896	951
Furniture, Fixtures and Leasehold Improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 5,847	$ 5,946

[1] Derived from our audited consolidated financial statements as of December 31, 2016.