GOODWILL, RADIO BROADCASTING LICENSES AND OTHER INTANGIBLE ASSETS (Details 2) - USD ($) $ in Millions		Dec. 31, 2018	Oct. 01, 2018		Mar. 31, 2018		Dec. 31, 2017	Oct. 01, 2017
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Impairment charge (in millions)		$ 21.3					$ 29.1
Radio Market Reporting Units [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Impairment charge (in millions)			$ 14.7	[1]	$ 2.7	[2]		$ 0.0	[1]
Discount Rate			9.00%	[1]		[2]		9.00%	[1]
Year 1 Market Revenue Growth Rate Range	[2]
Long-term Market Revenue Growth Rate Range (Years 6 – 10)	[2]
Mature Market Share Range	[2]
Mature Operating Profit Margin Range	[2]
Radio Market Reporting Units [Member] | Minimum [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range			(8.00%)					(8.40%)	[1]
Long-term Market Revenue Growth Rate Range (Years 6 – 10)	[1]		0.70%					0.50%
Mature Market Share Range	[1]		7.60%					8.00%
Mature Operating Profit Margin Range	[1]		26.80%					25.10%
Radio Market Reporting Units [Member] | Maximum [Member]
Schedule of Goodwill, Radio Broadcasting Licenses And Other Intangible Assets [Line Items]
Year 1 Market Revenue Growth Rate Range			27.50%					46.60%	[1]
Long-term Market Revenue Growth Rate Range (Years 6 – 10)	[1]		1.10%					1.50%
Mature Market Share Range	[1]		17.80%					18.20%
Mature Operating Profit Margin Range	[1]		46.90%					50.10%

[1] Reflects changes only to the key assumptions used in the interim testing for certain units of accounting.

[2] Goodwill fair value based on estimated asset sale consideration.