v3.26.1
Goodwill and intangible assets - Schedule of Finite-Lived Intangible Assets (Details) - USD ($)
$ in Millions
Jun. 30, 2026
Sep. 30, 2025
Jun. 30, 2025
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount $ 786.0 $ 786.2  
Trademarks and trade names - indefinite lived 641.1 640.8  
Accumulated Amortization (454.5) (415.6)  
Accumulated Impairment (5.9) (5.9)  
Net Carrying Amount 325.6 364.7  
Total Other intangible assets, net 966.7 1,005.5  
Trade names      
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount 154.9 155.0  
Accumulated Amortization (52.8) (46.4)  
Accumulated Impairment 0.0 0.0  
Net Carrying Amount 102.1 108.6  
Trade names | Rayovac      
Intangible Asset, Finite-Lived [Line Items]      
Net Carrying Amount     $ 337.0
Customer Relationships      
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount 394.9 395.0  
Accumulated Amortization (213.1) (193.3)  
Accumulated Impairment (0.6) (0.6)  
Net Carrying Amount 181.2 201.1  
Patents      
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount 34.5 34.5  
Accumulated Amortization (24.8) (23.3)  
Accumulated Impairment 0.0 0.0  
Net Carrying Amount 9.7 11.2  
Proprietary Technology      
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount 172.5 172.5  
Accumulated Amortization (145.2) (135.0)  
Accumulated Impairment 0.0 0.0  
Net Carrying Amount 27.3 37.5  
Proprietary Formula      
Intangible Asset, Finite-Lived [Line Items]      
Gross Carrying Amount 29.2 29.2  
Accumulated Amortization (18.6) (17.6)  
Accumulated Impairment (5.3) (5.3)  
Net Carrying Amount $ 5.3 $ 6.3