BUSINESS COMBINATIONS - Purchase Price Allocation (Details) - USD ($) $ in Thousands		12 Months Ended
	Nov. 09, 2020	Dec. 31, 2020	Dec. 31, 2019	Oct. 16, 2019	Jul. 19, 2019	May 09, 2019	Dec. 31, 2018	Sep. 27, 2018	Apr. 30, 2018
Business Acquisition [Line Items]
Goodwill		$ 62,215	$ 43,920				$ 539,469
QL Gaming Group
Business Acquisition [Line Items]
Net property and equipment	$ 8
Other assets, net of accumulated amortization	14,608
Goodwill	18,323
Total intangible and other assets	32,931
Deferred tax liabilities	(1,348)
Net working capital	12
Fair value of net assets acquired	$ 31,603
Cadence 13
Business Acquisition [Line Items]
Net property and equipment				$ 654
Operating lease right-of-use asset				62
Deferred tax asset				2,900
Other assets, net of accumulated amortization				5,977
Goodwill				31,392
Total intangible and other assets				40,331
Operating lease liabilities				(985)
Net working capital				(757)
Fair value of net assets acquired				$ 39,243
Pineapple Street Media
Business Acquisition [Line Items]
Accounts receivable, net of allowance for doubtful accounts					$ 997
Other assets, net of accumulated amortization					1,793
Goodwill					12,445
Assets					15,235
Other current liabilities					238
Accounts payable					30
Total liabilities					268
Fair value of net assets acquired					$ 14,967
2019 Cumulus Exchange
Business Acquisition [Line Items]
Net property and equipment						$ 844
Radio broadcasting licenses						19,576
Goodwill						2,080
Total intangible and other assets						21,656
Assets						22,500
Fair value of net assets acquired						$ 22,500
Jerry Lee
Business Acquisition [Line Items]
Net property and equipment								$ 981
Other assets, net of accumulated amortization								477
Radio broadcasting licenses								27,346
Goodwill								24,396
Total intangible and other assets								55,453
Assets								56,434
Net working capital								3,234
Fair value of net assets acquired								$ 56,434
Emmis
Business Acquisition [Line Items]
Net property and equipment									$ 1,558
Other assets, net of accumulated amortization									325
Radio broadcasting licenses									12,785
Goodwill									332
Total intangible and other assets									13,442
Assets									15,000
Fair value of net assets acquired									$ 15,000
Minimum | QL Gaming Group
Business Acquisition [Line Items]
Property and equipment, useful life	3 years
Finite-lived intangible assets acquired, useful life	3 years
Maximum
Business Acquisition [Line Items]
Property and equipment, useful life		40 years
Maximum | QL Gaming Group
Business Acquisition [Line Items]
Property and equipment, useful life	7 years
Finite-lived intangible assets acquired, useful life	10 years