v3.26.1
Accumulated Other Comprehensive Loss (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2026
Sep. 30, 2025
Mar. 31, 2025
Sep. 30, 2024
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 4,545.3      
Other comprehensive income (loss) (78.0)   $ 11.7  
Ending balance 4,914.7      
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest 322.4   164.4  
Accumulated Other Comprehensive Loss        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (340.2)   (367.2)  
Other comprehensive income (loss) (73.5)   11.5  
Ending balance (413.7) $ (413.7) (355.7) $ (355.7)
Other Comprehensive Income (Loss), before Reclassifications, before Tax   (70.6)   28.8
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax   (7.4)   (17.1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent   (78.0)   11.7
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest   4.5   (0.2)
Foreign Currency Translation Adjustment        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance (355.7)   (450.2)  
Ending balance   (436.1)   (410.9)
Other Comprehensive Income (Loss), before Reclassifications, before Tax   (85.0)   39.5
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax   0.0   0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent   (85.0)   39.5
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest   4.5   (0.2)
Net Unrealized (Loss)/Gain On Hedges        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance 15.3   82.8  
Ending balance   22.3   55.0
Other Comprehensive Income (Loss), before Reclassifications, before Tax   14.4   (10.7)
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax   (7.4)   (17.1)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent   7.0   (27.8)
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest   0.0   0.0
Net Unrealized Gain/(Loss) On  Available-for-sale Securities        
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]        
Beginning balance $ 0.2   $ 0.2  
Ending balance   0.1   0.2
Other Comprehensive Income (Loss), before Reclassifications, before Tax   (0.1)   0.0
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax   0.0   0.0
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent   (0.1)   0.0
Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest   $ 0.0   $ 0.0