v3.24.1.u1
Pensions and Postretirement Benefits Other than Pensions (Components of Net Periodic Postretirement Benefit Cost) (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2024
Mar. 31, 2023
Total $ (2.7) $ (5.6)
Postretirement Benefit Costs [Member]    
Service cost 0.3 0.4
Interest cost 2.9 3.3
Net amortization of prior service gains 0.1 0.2
Net amortization of plan net actuarial losses (3.3) (3.3)
Total 0.0 0.6
Postretirement Benefit Costs [Member] | Discontinued Operations [Member]    
Total (0.3) (0.1)
Operating Income (Loss) [Member] | Postretirement Benefit Costs [Member] | Continuing Operations [Member]    
Total 0.3 0.4
Other Nonoperating Income (Expense) [Member] | Postretirement Benefit Costs [Member] | Continuing Operations [Member]    
Total $ 0.0 $ 0.3