Pension and Postretirement Benefits (Amounts Recognized in Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Total recognized in accumulated other comprehensive loss	$ (8.8)	$ (7.7)
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	14.0	6.6
Prior service credit	(6.6)	(6.7)
Total recognized in accumulated other comprehensive loss	7.4	(0.1)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(7.9)	(5.7)
Prior service credit	$ (0.9)	$ (2.0)