v3.26.1
Defined Benefit and Postretirement Benefits (Components Of Net Periodic Cost) (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Pension        
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 0.8 $ 0.9 $ 1.6 $ 1.7
Interest cost 8.1 8.6 16.3 17.2
Expected return on plan assets (10.9) (11.1) (21.9) (22.1)
Amortization of prior service cost 0.2 0.2 0.4 0.4
Amortization of net loss (gain) 3.1 3.5 6.2 7.0
Net periodic loss (benefit) 1.3 2.1 2.6 4.2
Postretirement        
Defined Benefit Plan Disclosure [Line Items]        
Service cost 0.0 0.0 0.0 0.0
Interest cost 0.0 0.1 0.1 0.1
Expected return on plan assets 0.0 0.0 0.0 0.0
Amortization of prior service cost 0.0 0.0 0.0 0.0
Amortization of net loss (gain) (0.1) (0.1) (0.2) (0.2)
Net periodic loss (benefit) $ (0.1) $ 0.0 $ (0.1) $ (0.1)