Balance Sheet Components - Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Prepaid expenses and other current assets, net
Prepaid expenses	$ 5,990	$ 9,893
Other current assets, net	331	169
Total prepaid expenses and other current assets, net	$ 6,321	$ 10,062