Balance Sheet Components - Summary of Gross Unrealized Gains and Unrealized Losses of Investment Securities (Parenthetical) (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 87,036	$ 25,287	$ 12,409	$ 5,618
Commercial Paper [Member]
Schedule of Available-for-sale Securities [Line Items]
Cash and cash equivalents	$ 33,200	$ 8,000