Other Balance Sheet Accounts - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total of property and equipment	$ 25,473	$ 25,563
Less accumulated depreciation and amortization	(23,600)	(22,924)
Property and equipment, net	1,873	2,639
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total of property and equipment	17,425	17,515
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total of property and equipment	$ 8,048	$ 8,048