Long-lived Assets (Schedule of PP&E) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 13,522.1	$ 28,646.2
Accumulated depreciation	(7,349.5)	(14,802.8)
Accumulated depreciation	6,172.6	13,843.4
Distribution systems
Property, Plant and Equipment [Line Items]
Property and equipment gross	8,439.4	19,007.2
Customer premises equipment
Property, Plant and Equipment [Line Items]
Property and equipment gross	1,618.1	4,294.7
Support equipment, buildings and land
Property, Plant and Equipment [Line Items]
Property and equipment gross	$ 3,464.6	$ 5,344.3