Balance Sheet Information - Summary of Property and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 28,341	$ 27,595
Less: Accumulated depreciation and amortization	(15,492)	(14,590)
Land	1,770	1,770
Property and equipment, net	14,619	14,775
Building [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	6,207	6,207
Computers and office equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	9,443	9,968
Manufacturing and test equipment [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	10,665	9,495
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	1,211	1,256
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	698	519
Motor vehicles [Member]
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 117	$ 150