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Defined Benefit Plans - Components of Net Periodic Benefit Cost for Pension and Postretirement Benefits (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2022
Dec. 31, 2021
Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]      
Recognition of actuarial losses (gains) $ 1.2 $ (0.8) $ (3.2)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]     Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 0.2 0.4  
Interest cost 20.4 19.3  
Recognition of actuarial losses (gains) 155.9 26.2  
Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 0.4 0.2  
Interest cost 0.4 0.2  
Recognition of actuarial losses (gains) 1.2 1.0  
Net Periodic Benefit Cost | Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 0.2 0.4 $ 5.2
Interest cost 20.4 19.3 35.2
Expected return on plan assets (28.1) (27.4) (33.3)
Recognition of actuarial losses (gains) (0.3) 1.1 2.1
Settlement/Curtailment losses (gains) 0.0   0.6
Net periodic benefit (income) cost (7.8) (6.6) (0.6)
Net Periodic Benefit Cost | Postretirement Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Service cost 0.4 0.2  
Interest cost 0.4 0.2  
Recognition of actuarial losses (gains) (1.0) (0.5) (0.1)
Net periodic benefit (income) cost $ (0.2) $ (0.1) $ (0.1)