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Components of Net Periodic Benefit Cost (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2024
Mar. 31, 2023
Pension benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Service cost $ 0.6 $ 1.1
Interest cost 3.5 2.6
Expected return on plan assets (3.8) (5.9)
Amortization of prior service costs 0.1 0.0
Amortization of net loss 1.7 0.9
Net periodic benefit cost (income) 2.1 (1.3)
Other postretirement benefits    
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]    
Interest cost 1.0 0.7
Amortization of net loss 0.0 0.3
Net periodic benefit cost (income) $ 1.0 $ 1.0