Employee Benefits - Amounts Recognized on the Balance Sheets (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	$ 916.7	$ 881.3
Pension and OPEB obligations	171.6	219.0
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	470.6	389.0
Pension and OPEB obligations	158.5	196.7
Total net assets	312.1	192.3
OPEB Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension and OPEB assets	446.1	492.3
Pension and OPEB obligations	13.1	22.3
Total net assets	$ 433.0	$ 470.0