Balance Sheet Details - Summary of Equipment and Improvements (Detail) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Gross, Total	$ 22,672	$ 22,526
Less accumulated depreciation and amortization	(20,180)	(18,253)
Equipment and improvements, net	2,492	4,273
Computer hardware, software, and equipment [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	16,288	16,143
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	5,170	5,170
Office furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	$ 1,214	$ 1,213