PROPERTY, PLANT AND EQUIPMENT, INTANGIBLE ASSETS AND GOODWILL - Annual Impairment Test to Goodwill (Narrative) (Details)	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($) market	Dec. 31, 2016 USD ($) market
Goodwill [Line Items]
Goodwill impairment	$ 0	$ 1,591,000
iHM
Goodwill [Line Items]
Goodwill impairment		0
Cumulative impairments			$ 3,500,000,000
Americas Outdoor Advertising
Goodwill [Line Items]
Goodwill impairment		0
Cumulative impairments			2,600,000,000
International Outdoor Advertising
Goodwill [Line Items]
Goodwill impairment		$ 1,591,000	7,300,000
Cumulative impairments			$ 270,500,000
International Outdoor Advertising | Goodwill
Goodwill [Line Items]
Number of markets | market		1	1
Other
Goodwill [Line Items]
Goodwill impairment		$ 0
Cumulative impairments			$ 212,000,000