v3.26.1
Financial Instruments and Risk Management - Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) (Details) - Designated as Hedging Instrument - Cash Flow Hedging - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Derivative Instruments, Gain (Loss) [Line Items]          
Derivatives - Foreign Currency contracts $ 23.6   $ 23.6   $ 22.9
(Loss)/Gain Recognized in OCI 4.9 $ (10.5) 8.8 $ 4.9  
(Loss)/Gain Reclassified From OCI into Income 3.3 6.5 8.1 22.8  
Foreign currency contracts          
Derivative Instruments, Gain (Loss) [Line Items]          
Derivatives - Foreign Currency contracts 0.8   0.8   (3.9)
(Loss)/Gain Recognized in OCI 0.8 (9.7)      
(Loss)/Gain Reclassified From OCI into Income (1.3) 0.3      
Interest rate swap          
Derivative Instruments, Gain (Loss) [Line Items]          
Derivatives - Foreign Currency contracts 19.4   19.4   25.3
(Loss)/Gain Recognized in OCI 2.1 (1.4) 5.6 6.9  
(Loss)/Gain Reclassified From OCI into Income 3.4 5.1 11.5 16.9  
Zinc contracts          
Derivative Instruments, Gain (Loss) [Line Items]          
Derivatives - Foreign Currency contracts 3.4   3.4   $ 1.5
(Loss)/Gain Recognized in OCI 2.0 0.6 3.0 (1.4)  
(Loss)/Gain Reclassified From OCI into Income $ 1.2 $ 1.1 1.1 3.4  
Foreign currency contracts          
Derivative Instruments, Gain (Loss) [Line Items]          
(Loss)/Gain Recognized in OCI     0.2 (0.6)  
(Loss)/Gain Reclassified From OCI into Income     $ (4.5) $ 2.5