INTANGIBLE ASSETS AND GOODWILL - Changes in Carrying Value of Broadcasting Licenses (Details) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Indefinite-lived Intangible Assets [Roll Forward]
Broadcasting licenses balance as of January 1,	$ 2,229,016	$ 2,508,121
Disposition of radio stations (See Note 2)	0	(432)
Acquisitions	23,233	0
Loss on impairment	0	(261,929)
Assets held for sale (See Note 14)	0	(16,744)
Ending period balance	$ 2,252,249	$ 2,229,016