GOODWILL, RADIO BROADCASTING LICENSES AND OTHER INTANGIBLE ASSETS - Goodwill Valuation Results (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
GOODWILL AND RADIO BROADCASTING LICENSES
Gross goodwill	$ 378,079	$ 378,079	$ 378,079
Accumulated impairment losses	(132,507)	(138,307)	(132,507)
Additions		0	0
Impairments		(15,900)	(5,800)
Assets held for sale		(470)
Net goodwill	239,772	223,402	239,772
Radio Broadcasting Segment [Member]
GOODWILL AND RADIO BROADCASTING LICENSES
Gross goodwill	155,000	155,000	155,000
Accumulated impairment losses	(101,848)	(101,848)	(101,848)
Additions		0	0
Impairments		(15,900)	0
Assets held for sale		(470)
Net goodwill	53,152	36,782	53,152
Reach Media Segment [Member]
GOODWILL AND RADIO BROADCASTING LICENSES
Gross goodwill	30,468	30,468	30,468
Accumulated impairment losses	(16,114)	(16,114)	(16,114)
Additions		0	0
Impairments		0	0
Assets held for sale		0
Net goodwill	14,354	14,354	14,354
Digital Segment [Member]
GOODWILL AND RADIO BROADCASTING LICENSES
Gross goodwill	27,567	27,567	27,567
Accumulated impairment losses	(14,545)	(20,345)	(14,545)
Additions		0	0
Impairments	(5,800)	0	(5,800)
Assets held for sale		0
Net goodwill	7,222	7,222	7,222
Cable Television Segment [Member]
GOODWILL AND RADIO BROADCASTING LICENSES
Gross goodwill	165,044	165,044	165,044
Accumulated impairment losses	0	0	0
Additions		0	0
Impairments		0	0
Assets held for sale		0
Net goodwill	$ 165,044	$ 165,044	$ 165,044