PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 189,174	$ 181,367
Accumulated depreciation and amortization	167,592	159,464
Property, plant and equipment, net	21,582	21,903
Capitalized Computer Software, Additions	4,500	1,900	$ 1,300
Capitalized Computer Software, Amortization	2,500	2,800	3,000
Annual depreciation and amortization	$ 11,900	13,100	$ 15,200
Internal Use Software [Domain]
Property, Plant and Equipment [Line Items]
Capitalized Computer Software, Useful Life	3 years
Computer and video equipment and software [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 132,531	127,322
Manufacturing tooling and testbeds [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	3,635	3,591
Office equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,957	5,036
Furniture, fixtures and other [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	10,458	10,639
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 37,593	$ 34,779