Balance Sheet Details - Summary of Equipment and Improvements (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Gross, Total	$ 22,526	$ 23,059
Less accumulated depreciation and amortization	(18,253)	(16,036)
Equipment and improvements, net	4,273	7,023
Computer hardware, software, and equipment [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	16,143	16,529
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	5,170	5,317
Office furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Gross, Total	$ 1,213	$ 1,213