PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 171,682	$ 164,897
Less: Accumulated depreciation and amortization	(145,594)	(139,716)
Property and equipment, net	26,088	25,181
Land and improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 3,491	2,391
Property, Plant and Equipment, Estimated Useful Lives	0 years
Buildings [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 2,754	2,660
Property, Plant and Equipment, Estimated Useful Lives	31 years
Transmitters and towers [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 41,854	40,343
Transmitters and towers [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	15 years
Transmitters and towers [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	7 years
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 60,872	59,024
Equipment [Member] | Maximum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	7 years
Equipment [Member] | Minimum [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Estimated Useful Lives	3 years
Furniture and fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 9,699	10,354
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	$ 27,330	25,398
Property, Plant and Equipment, Estimated Useful Lives	3 years
Leasehold improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 25,407	24,543
Property, Plant and Equipment, Estimated Useful Lives	Lease Term
Construction-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 275	$ 184
Property, Plant and Equipment, Estimated Useful Lives	0 years