PROPERTY, PLANT AND EQUIPMENT, INTANGIBLE ASSETS AND GOODWILL - Narrative (Detail) $ in Thousands		3 Months Ended				9 Months Ended		12 Months Ended
	Oct. 24, 2016 USD ($)	Sep. 30, 2016 USD ($)	Jun. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) station market	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Disposal Groups, Including Discontinued Operations [Line Items]
Current assets		$ 55,184				$ 55,184		$ 295,075
Impairment charges related to indefinite-lived intangible assets		700			$ 21,600	700	$ 21,600
Amortization expense		55,600			$ 57,300	167,700	180,900
Goodwill impairment								$ 7,274
Disposed of by sale | Broadcast communication tower sites and related assets
Disposal Groups, Including Discontinued Operations [Line Items]
Number of radio stations sold | station				6
Disposal proceeds				$ 5,500
Gain (loss) on disposal				2,700
Deferred portion of gain on asset disposal				1,900
Disposed of by sale | Non-strategic outdoor markets
Disposal Groups, Including Discontinued Operations [Line Items]
Disposal proceeds				592,600
Gain (loss) on disposal				$ 278,300
Number of markets sold | market				9
Disposed of by sale | International Outdoor, Turkey
Disposal Groups, Including Discontinued Operations [Line Items]
Gain (loss) on disposal			$ (56,600)
Foreign currency translation adjustments			$ 32,200
Disposed of by sale | Australia Outdoor
Disposal Groups, Including Discontinued Operations [Line Items]
Current assets		48,600				48,600
Property, plant and equipment		56,200				56,200
Other assets		5,700				5,700
Current liabilities		31,100				31,100
Long-term liabilities		9,000				9,000
Revenue						96,000	83,600
Direct expenses						56,200	51,900
SG&A expenses						18,500	16,100
Depreciation and amortization						9,400	$ 7,300
Held-for-sale | Outdoor market Indianapolis
Disposal Groups, Including Discontinued Operations [Line Items]
Disposal proceeds				$ 41,200
International Outdoor
Disposal Groups, Including Discontinued Operations [Line Items]
Goodwill impairment		$ 7,300				$ 7,300
Subsequent Event | Disposed of by sale | Australia Outdoor
Disposal Groups, Including Discontinued Operations [Line Items]
Cash proceeds from sale of ownership interest	$ 203,900