Balance Sheet Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 33,293	$ 32,300
Less: Accumulated depreciation and amortization	(21,448)	(20,231)
Land	1,770	1,770
Property and equipment, net	13,615	13,839
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6,227	6,227
Computers and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	11,609	10,931
Manufacturing and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	12,952	12,826
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,230	1,273
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,233	1,001
Motor Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 42	$ 42