Balance Sheet Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 34,435	$ 33,318
Less: Accumulated depreciation and amortization	(23,146)	(22,479)
Land	1,770	1,770
Property and equipment, net	13,059	12,609
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6,351	6,351
Computers and Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	12,393	11,577
Manufacturing and Test Equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	13,160	12,940
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,258	1,239
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,254	1,191
Motor Vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 19	$ 20