INTANGIBLE ASSETS AND GOODWILL (Details) $ in Thousands	3 Months Ended				12 Months Ended
	Jun. 30, 2017 number	Jun. 30, 2016 number	Jun. 30, 2014 number	Jun. 30, 2013 number	Dec. 31, 2017 USD ($) number	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Changes in broadcasting licenses [Line Items]
Beginning of period balance					$ 823,195	$ 807,381
Consolidation of a VIE					(15,738)	15,738
Acquisition of radio stations					17,174	0
Disposition of Licenses - EMF Sale					54,661	0
Acqusition of radio Stations - Beasley Transaction					35,944	0
Acquisition of radio stations - iHeartMedia Transaction					50,621	0
Disposition of radio stations - iHeartMedia Transaction					7,462	0
Assets held for sale					(66,014)	0
Deconsolidation of a subsidiary					0	(36)
Acquisition - other					0	112
Dispositions					(13,500)	0
Indefinitelived Intangible Assets Acquired Through Exchange					0	0
Ending period balance					$ 2,649,959	823,195
Market approach for step one goodwill analysis [Abstract]
Income model years used for the discounted cash flow approach | number					10
Changes in goodwill [Roll Forward]
Goodwill before cumulative loss on impairment						158,333	$ 158,244
Accumulated loss on impairment						(125,615)	$ (125,615)
Beginning balance after cumulative loss on impairment					$ 32,718	32,629
Loss on impairment during the year					(441)	0
Acquisition					820,961	0
Dispositions					0	(3)
Disposition of radio station - EMF sale					266	0
Acquisition of radio station - iHeartMedia Transaction					11,700	0
Disposition of radio station - iHeartMedia Transaction					14	0
Acquisition of radio station - Beasley Transaction					289	0
Assets held for sale					(2,990)	0
Deconsolidation of a subsidiary					0	0
Goodwill Acquired Through Exchange					0	0
Adjustments to acquired goodwill					0	92
Ending balance					862,000	32,718
Broadcasting License Impairment Testing [Member]
Estimates and assumptions used for impairment test [Line Items]
Discount rates	9.25%	9.50%	9.70%	9.60%
Broadcasting License Impairment Testing [Member] | Maximum [Member]
Estimates and assumptions used for impairment test [Line Items]
Operating profit margin ranges of the markets of the Company	40.00%	40.00%	40.00%	40.00%
Long-term revenue growth rate ranges of the markets of the Company	2.00%	2.00%	2.00%	2.00%
Broadcasting License Impairment Testing [Member] | Minimum [Member]
Estimates and assumptions used for impairment test [Line Items]
Operating profit margin ranges of the markets of the Company	19.00%	14.00%	25.00%	25.00%
Long-term revenue growth rate ranges of the markets of the Company	1.00%	1.00%	1.50%	1.50%
Goodwill Impairment Testing [Member]
Estimates and assumptions used for impairment test [Line Items]
Discount rates	9.25%	9.50%	9.70%	9.60%
Goodwill Impairment Testing [Member] | Maximum [Member]
Estimates and assumptions used for impairment test [Line Items]
Long-term revenue growth rate ranges of the markets of the Company	2.00%	2.00%	2.00%	2.00%
Market approach for step one goodwill analysis [Abstract]
Estimates of market multiples | number	8	8	8	8
Goodwill Impairment Testing [Member] | Minimum [Member]
Estimates and assumptions used for impairment test [Line Items]
Long-term revenue growth rate ranges of the markets of the Company	1.00%	1.00%	1.50%	1.50%
Market approach for step one goodwill analysis [Abstract]
Estimates of market multiples | number	7.5	7.5	7.5	7.5
Radio Broadcasting Licences [Member]
Changes in broadcasting licenses [Line Items]
Acquisition of radio stations - CBS Radio Merger					$ 1,880,400	$ 0