PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 164,897	$ 158,793
Less: Accumulated depreciation and amortization	(139,716)	(133,942)
Property and equipment, net	25,181	24,851
Land and improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,391	2,830
Property, Plant and Equipment, Estimated Useful Lives	0 years
Building [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,660	1,264
Property, Plant and Equipment, Estimated Useful Lives	31 years
Transmitters and towers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 40,343	39,266
Transmitters and towers [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	7 years
Transmitters and towers [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	15 years
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 59,024	57,218
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 years
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	7 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 10,354	10,153
Property, Plant and Equipment, Estimated Useful Lives	6 years
Software and web development [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 25,398	23,679
Property, Plant and Equipment, Estimated Useful Lives	3 years
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 24,543	24,248
Property, Plant and Equipment, Estimated Useful Lives	Lease Term
Construction-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 184	$ 135
Property, Plant and Equipment, Estimated Useful Lives	0 years