Income Taxes - Differences in Provision for Income Taxes from Amount Computed by Applying Statutory U.S. Federal Income Tax Rate to Loss from Operations Before Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Abstract]
U.S. statutory rate	$ (4,122)	$ (828)	$ (21,181)
Permanent items and foreign tax credits	(476)	149	292
Uncertain tax positions	2,523	817	809
Research credits	(120)	(1,204)	(1,346)
State and local taxes	478	234	(1,780)
Impact of rate change on deferred taxes	749	61	31
True-up of prior year tax	1,191	1,065	(1,465)
Foreign tax rate differential	46	437	92
Valuation allowance	2,704	958	25,631
Tax on repatriation		(500)	(18)
Other	(5)	6	(51)
Provision (benefit) for income taxes	$ 2,968	$ 1,195	$ 1,014