Long-lived Assets (Property and Equipment, Net) (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 9,748.4	$ 9,063.8
Accumulated depreciation	(5,158.7)	(4,737.8)
Total property and equipment, net	4,589.7	4,326.0
Distribution systems
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	6,149.7	5,702.7
Support equipment, buildings and land
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	2,686.5	2,518.0
CPE
Property, Plant and Equipment [Line Items]
Total property and equipment, gross	$ 912.2	$ 843.1