Income Taxes - Components of Deferred Income Taxes (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Deferred tax liability, net	$ 4,625.6	$ 4,308.5
Deferred Tax Assets
Tax gross up - regulatory items	459.0	469.5
Future tax benefits	187.7	104.6
Deferred revenues	86.8	97.8
Other	190.2	205.9
Total deferred tax assets	923.7	877.8
Valuation allowance	(1.2)	(1.2)
Net deferred tax assets	922.5	876.6
Deferred Tax Liabilities
Property-related	4,072.5	3,909.0
Investment in affiliates	839.7	648.6
Employee benefits and compensation	219.5	170.6
Deferred costs - plant retirements	212.8	223.9
Other	203.6	233.0
Total deferred tax liabilities	$ 5,548.1	$ 5,185.1