PROPERTY AND EQUIPMENT (Schedule of Property and Equipment) (Details) - USD ($) $ in Millions	8 Months Ended	12 Months Ended
	Feb. 28, 2018	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 8,075.5	$ 6,962.5
Less accumulated depreciation		(2,592.6)	(1,946.5)
Less property and equipment held for sale		(35.7)
Property, Plant and Equipment, Net, Total		5,447.2	5,016.0
Land [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		29.6	28.9
Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 321.8	277.1
Building Improvements [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		15 years
Building Improvements [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		45 years
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 61.7	27.3
Furniture and Fixtures [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		3 years
Furniture and Fixtures [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		7 years
Computer Hardware [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 42.7	33.1
Computer Hardware [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		3 years
Computer Hardware [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		5 years
Software [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life in years		3 years
Property and equipment, gross		$ 70.1	56.5
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 585.1	483.4
Machinery and Equipment [Member] | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		5 years
Machinery and Equipment [Member] | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life in years		7 years
Fiber Optic Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life in years		8 years
Property and equipment, gross		$ 1,086.6	904.9
Circuit Switch Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life in years		10 years
Property and equipment, gross		$ 399.4	337.6
Packet Switch Equipment [Member]
Property, Plant and Equipment [Line Items]
Estimated useful life in years		5 years
Property and equipment, gross		$ 58.1	51.9
Fiber optic network
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 4,954.9	4,110.3
Fiber optic network | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life in years	15 years	33 years
Fiber optic network | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life in years	20 years
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, gross		$ 465.5	$ 651.5