Balance Sheet Components - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Cash	$ 1,653	$ 1,576
Cash equivalents:
Money market accounts	139,218	148,604
Total cash and cash equivalents	$ 140,871	$ 150,180	$ 24,054	$ 29,154