Balance Sheet Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 31,959	$ 30,784
Less: Accumulated depreciation and amortization	(19,687)	(17,712)
Land	1,770	1,770
Property and equipment, net	14,042	14,842
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6,231	6,229
Computers and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	10,816	10,435
Manufacturing and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	12,720	11,880
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,275	1,214
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	875	909
Motor Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 42	$ 117