SUPPLEMENTAL CASH FLOW DISCLOSURES ON NON-CASH ACTIVITIES (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Operating Activities
Barter revenues	$ 9,616	$ 16,914	$ 19,365
Barter expenses	9,604	16,741	19,324
Transition services costs incurred in the integration of CBS Radio	0	0	5,456
Reduction to the transition services asset	0	0	(5,456)
Financing Activities
Increase in paid-in capital from the issuance of RSUs	10,073	12,926	10,078
Decrease in paid-in capital from the forfeiture of RSUs	(624)	(1,753)	(1,228)
Net paid-in capital of RSUs issued (forfeited)	9,449	11,173	8,850
Investing Activities
Noncash additions to property and equipment and intangibles	2,901	803	818
Net radio station assets given up in a market	0	22,795	0
Net radio station assets acquired in a market	$ 0	$ 22,500	$ 0