Property, Plant and Equipment (Details) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Years	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Land and rights-of-way	$ 4.3	$ 4.3
Buildings and leasehold improvements	173.7	165.0
Network equipment	3,165.7	2,959.3
Office software, furniture, fixtures and vehicles	150.6	131.4
Construction in process	17.0	29.2
Gross value	3,511.3	3,289.2
Accumulated depreciation	(2,425.8)	(2,313.7)
Property, plant and equipment, net	1,085.5	975.5
Depreciation	$ 182.0	$ 141.3	$ 127.2
Depreciation associated with cost of providing services	85.00%	79.00%	81.00%
Impairment of assets, excluding goodwill	$ 0.0	$ 0.0
Capital Lease and Other Financing Arrangements Assets, Gross	$ 96.8	91.2
Capital Leases, Net of Depreciation, Retained After Sale of Business, Affiliate and Productive Assets		$ 57.7
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	20 years
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life, Minimum in Practice | Years	7
Property, Plant and Equipment, Useful Life, Maximum in Practice | Years	22
copper assets [Member]
Property, Plant and Equipment [Line Items]
property, plant, and equipment, copper asset useful life, prior to remeasurement		15
property, plant, and equipment, copper assets useful life, after remeasurement		7
Entertainment and Communications [Member]
Property, Plant and Equipment [Line Items]
Impairment of assets, excluding goodwill			$ 4.6
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Minimum [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	40 years
Maximum [Member] | Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	50 years
Maximum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Useful Life	14 years