Long-lived Assets - Property and Equipment, Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 7,594.3	$ 7,119.8
Accumulated depreciation	(3,293.2)	(2,882.9)
Accumulated depreciation	4,301.1	4,236.9
Depreciation expense	697.0	641.0	$ 596.0
Non-cash increases related to vendor financing arrangements	96.1	53.9	$ 54.9
Distribution systems
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 4,299.6	4,115.0
Distribution systems | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Distribution systems | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	25 years
Customer premises equipment
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,763.8	1,606.0
Customer premises equipment | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Customer premises equipment | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	5 years
Support equipment, buildings and land
Property, Plant and Equipment [Line Items]
Property and equipment, gross	$ 1,530.9	$ 1,398.8
Support equipment, buildings and land | Minimum
Property, Plant and Equipment [Line Items]
Estimated useful life	3 years
Support equipment, buildings and land | Maximum
Property, Plant and Equipment [Line Items]
Estimated useful life	40 years