Employee Benefits - Amounts Recognized on the Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	$ 968.5	$ 870.9
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	562.4	475.2
Pension and OPEB obligations	147.3	161.8
Total net assets	415.1	313.4
OPEB Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	406.1	395.7
Pension and OPEB obligations	17.0	14.2
Total net assets	$ 389.1	$ 381.5