Financial Statement Components - Summary of Carrying Values of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite Lived Intangible Assets [Line Items]
Cost	$ 3,850	$ 3,850
Accumulated Amortization	2,388	1,606
Acquired Intangibles, Net	$ 1,462	$ 2,244
Customer Relationships
Finite Lived Intangible Assets [Line Items]
Estimated Lives	2 years	2 years
Cost	$ 840	$ 840
Accumulated Amortization	$ 840	660
Acquired Intangibles, Net		$ 180
Developed Technology
Finite Lived Intangible Assets [Line Items]
Estimated Lives	5 years	5 years
Cost	$ 3,010	$ 3,010
Accumulated Amortization	1,548	946
Acquired Intangibles, Net	$ 1,462	$ 2,064