Balance Sheet Components - Summary of Cash and Cash Equivalents (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Cash and Cash Equivalents [Abstract]
Cash	$ 2,210	$ 1,576
Cash equivalents:
Money market accounts	128,340	148,604
Total cash and cash equivalents	$ 130,550	$ 150,180	$ 15,800	$ 29,154