Income Taxes - Differences in Total Provision for (Benefit from) Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Tax benefit at U.S. statutory rate	$ (5,126)	$ (10,997)	$ (11,773)
State income taxes, net of federal benefit	(147)	(104)	(105)
Foreign income and withholding taxes	4,317	6,033	3,593
Stock-based compensation	2,231	1,039	984
Change in valuation allowance	155	3,807	5,982
Research and development credits	(736)	(1,067)	(807)
Uncertain tax positions	1,146	1,277	52
Provision to return adjustments	(484)	848	(53)
Other	48	169	671
Provision for (benefit from) income taxes	$ 1,404	$ 1,005	$ (1,456)