GOODWILL, RADIO BROADCASTING LICENSES AND OTHER INTANGIBLE ASSETS - Valuation of Broadcasting Licenses (Details) - USD ($) $ in Millions	Dec. 31, 2019	Oct. 01, 2019	Jun. 30, 2019	Dec. 31, 2018	Oct. 01, 2018	Mar. 31, 2018
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Impairment charge (in millions)	$ 10.6			$ 21.3
Radio Broadcasting Licenses [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Impairment charge (in millions)		$ 1.0	$ 3.8			$ 3.9
Discount Rate		9.00%			9.00%
Radio Broadcasting Licenses [Member] | Maximum [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range		1.80%			(0.60%)
Long-term Market Revenue Growth Rate Range (Years 6 - 10)		1.10%			1.10%
Mature Market Share Range		25.00%			25.00%
Mature Operating Profit Margin Range		39.70%			41.10%
Radio Broadcasting Licenses [Member] | Minimum [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range		0.90%			(1.20%)
Long-term Market Revenue Growth Rate Range (Years 6 - 10)		0.70%			0.70%
Mature Market Share Range		6.90%			5.30%
Mature Operating Profit Margin Range		27.60%			28.30%