Long-lived Assets (Schedule of PP&E) (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 14,387.7	$ 15,062.5
Accumulated depreciation	(7,707.2)	(8,081.0)
Total property and equipment, net	6,680.5	6,981.5
Distribution systems
Property, Plant and Equipment [Line Items]
Property and equipment gross	9,237.5	9,472.8
Support equipment, buildings and land
Property, Plant and Equipment [Line Items]
Property and equipment gross	3,839.8	4,310.5
Customer premises equipment
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 1,310.4	$ 1,279.2