v3.26.1
Accumulated Other Comprehensive Loss, Net (Details) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance $ 2,699.3 $ 1,882.0 $ 2,377.4 $ 1,709.1
Other comprehensive loss, net of tax (4.8) 17.6 (22.9) 11.0
Ending balance 2,844.0 1,978.8 2,844.0 1,978.8
Foreign Currency Translation Adjustment        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance     (21.4)  
Other comprehensive loss, net of tax     (0.8)  
Ending balance (22.2)   (22.2)  
Pension Benefits Adjustment        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance     (1.3)  
Other comprehensive loss, net of tax     0.0  
Ending balance (1.3)   (1.3)  
Cash Flow Hedge        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance     6.7  
Other comprehensive loss, net of tax     (22.1)  
Ending balance (15.4)   (15.4)  
Accumulated Other Comprehensive Loss, net        
AOCI Attributable to Parent, Net of Tax [Roll Forward]        
Beginning balance (34.1) (31.8) (16.0) (25.2)
Other comprehensive loss, net of tax (4.8) 17.6 (22.9) 11.0
Ending balance $ (38.9) $ (14.2) $ (38.9) $ (14.2)