v3.25.2
Goodwill and intangible assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($)
$ in Millions
 9 Months Ended
Jun. 30, 2025
Sep. 30, 2024
Finite-Lived Intangible Assets [Line Items]    
Cumulative translation adjustment $ 4.0  
Gross Carrying Amount 786.8 $ 786.2
Trademarks and trade names - indefinite lived 640.9 641.6
Total Other intangible assets, net 1,427.7 1,427.8
Accumulated Amortization (401.5) (356.9)
Net Carrying Amount 385.3 429.3
Total Other intangible assets, net 1,026.2 1,070.9
Trademarks and trade names - indefinite lived    
Finite-Lived Intangible Assets [Line Items]    
Trademarks and trade names - indefinite lived   641.6
Trade names    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 155.2 155.0
Accumulated Amortization (44.4) (37.8)
Net Carrying Amount 110.8 117.2
Customer Relationships    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 395.2 395.0
Accumulated Amortization (186.9) (166.8)
Net Carrying Amount 208.3 228.2
Patents    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 34.7 34.5
Accumulated Amortization (22.9) (21.0)
Net Carrying Amount 11.8 13.5
Proprietary Technology    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 172.5 172.5
Accumulated Amortization (130.6) (117.5)
Net Carrying Amount 41.9 55.0
Proprietary Formula    
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 29.2 29.2
Accumulated Amortization (16.7) (13.8)
Net Carrying Amount $ 12.5 $ 15.4