v3.26.3
Benefit Plans (Net Periodic Benefit Cost (Income)) (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Contributions by employer     $ 7.5 $ 7.5
Pension [Member]        
Service cost     1.5 1.6
Interest cost     9.5 11.0
Expected return on assets     (11.3) (11.8)
Prior service cost     0.7 0.7
Actuarial loss / (gain)     3.2 3.8
Net periodic benefit cost     $ 3.6 $ 5.3
Subsidiaries [Member] | Pension [Member]        
Service cost $ 0.5 $ 0.5    
Interest cost 3.2 3.7    
Expected return on assets (3.8) (3.9)    
Prior service cost 0.2 0.2    
Actuarial loss / (gain) 1.1 1.3    
Net periodic benefit cost $ 1.2 $ 1.8