GOODWILL, RADIO BROADCASTING LICENSES AND OTHER INTANGIBLE ASSETS - Radio Market Reporting Units (Details) - USD ($)					3 Months Ended		12 Months Ended
	Oct. 01, 2021	Oct. 01, 2020	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Pre-tax impairment charge							$ 0	$ 84,400,000
Radio Market Reporting Units [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Pre-tax impairment charge	$ 0	$ 0	$ 10,000,000.0	$ 5,900,000	$ 10,000,000.0	$ 5,900,000
Discount Rate	9.00%	9.00%	9.00%	9.50%	9.00%	9.50%
Radio Market Reporting Units [Member] | Minimum
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range	(10.70%)	(12.90%)	(26.60%)	(14.50%)	(26.60%)	(14.50%)
Long-term Market Revenue Growth Rate Range (Years 6 - 10)	0.70%	0.70%	0.90%	0.90%	0.90%	0.90%
Mature Market Share Range	6.20%	6.80%	8.40%	11.10%	8.40%	11.10%
Operating Profit Margin Range	21.20%	27.70%	27.70%	29.40%	27.70%	29.40%
Radio Market Reporting Units [Member] | Maximum
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range	25.40%	25.90%	34.70%	(12.90%)	34.70%	(12.90%)
Long-term Market Revenue Growth Rate Range (Years 6 - 10)	1.00%	1.10%	1.10%	1.10%	1.10%	1.10%
Mature Market Share Range	16.00%	16.80%	12.70%	13.00%	12.70%	13.00%
Operating Profit Margin Range	47.30%	49.10%	48.10%	39.00%	48.10%	39.00%