INTANGIBLE ASSETS AND GOODWILL - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived permits	$ 843,849		$ 965,863
Gross Carrying Amount	1,530,167		1,754,095
Accumulated Amortization	(378,143)		(461,567)
Impairment of indefinite-lived permits	123,137	$ 0	0
Transit, street furniture and other outdoor contractual rights
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	434,171		535,912
Accumulated Amortization	(366,112)		(451,021)
Permanent easements
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	163,399		163,399
Accumulated Amortization	0		0
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	83,569		83,569
Accumulated Amortization	(7,981)		(5,898)
Other
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	5,179		5,352
Accumulated Amortization	$ (4,050)		$ (4,648)