Property and Equipment Details of property and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 76,775	$ 68,568
Less: Accumulated depreciation	(63,438)	(58,923)
Property and equipment, net	13,337	9,645
Buildings and Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,581	1,623
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	32,743	30,479
Computer and Communication Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	24,637	19,744
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	1,267	1,319
Vehicles [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	357	215
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	15,546	15,173
Construction in Process [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 644	$ 15