PROPERTY AND EQUIPMENT (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Towers	$ 12,777.9	$ 12,500.5
Equipment	1,667.3	1,423.0
Buildings and improvements	628.5	631.4
Land and improvements	2,285.4	2,112.9
Construction-in-progress	358.1	282.1
Total	17,717.2	16,949.9
Less accumulated depreciation	(6,470.1)	(5,848.9)
Property and equipment, net	$ 11,247.1	$ 11,101.0
Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Tower | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years
Equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	2 years
Equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	15 years
Buildings and Improvements | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful lives	3 years
Buildings and Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	32 years
Land and Improvements | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful lives	20 years