Balance Sheet Information (Details 1) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Summary of property and equipment
Total property and equipment	$ 28,158	$ 27,597
Less: Accumulated depreciation and amortization	(15,226)	(14,590)
Land	1,770	1,770
Property and equipment, net	14,702	14,777
Building [Member]
Summary of property and equipment
Total property and equipment	6,207	6,207
Computers and office equipment [Member]
Summary of property and equipment
Total property and equipment	10,194	9,970
Manufacturing and test equipment [Member]
Summary of property and equipment
Total property and equipment	9,769	9,495
Furniture and fixtures [Member]
Summary of property and equipment
Total property and equipment	1,258	1,256
Leasehold improvements [Member]
Summary of property and equipment
Total property and equipment	580	519
Motor Vehicles [Member]
Summary of property and equipment
Total property and equipment	$ 150	$ 150