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Retirement Plans - Components of Net Periodic Benefit Cost (Credit) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2022
Sep. 30, 2021
Sep. 30, 2022
Sep. 30, 2021
Defined Benefit Pension Plan        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 4.7 $ 5.5 $ 14.7 $ 16.6
Interest cost 2.1 1.5 6.6 4.6
Expected return on assets (3.6) (3.1) (11.1) (9.2)
Net loss 0.5 0.0 1.4 0.0
Prior service cost (credit) 0.2 1.4 0.5 4.1
Total benefit cost (credit) 3.9 5.3 12.1 16.1
Retiree Health Care Plan        
Defined Benefit Plan Disclosure [Line Items]        
Interest cost 0.1 0.1 0.2 0.2
Net loss 0.0 0.0 0.1 0.1
Prior service cost (credit) (0.2) (0.2) (0.6) (0.6)
Total benefit cost (credit) $ (0.1) $ (0.1) $ (0.3) $ (0.3)