v3.25.1
Intangible Assets - Gross and Net Intangible Assets by Major Class (Details) - USD ($)
$ in Millions
Mar. 31, 2025
Sep. 30, 2024
Acquired Finite-Lived Intangible Assets [Line Items]    
Finite-lived intangible assets, gross amount $ 35.4 $ 46.7
Finite-lived intangible assets, accumulated amortization (19.0) (32.9)
Total intangible assets subject to amortization 16.4 13.8
Indefinite-lived intangible assets 5.8 5.8
Intangible assets, gross amount 41.2 52.5
Total intangible assets, net amount 22.2 19.6
Website domains    
Acquired Finite-Lived Intangible Assets [Line Items]    
Indefinite-lived license agreements 2.1 2.1
Business licenses    
Acquired Finite-Lived Intangible Assets [Line Items]    
Indefinite-lived intangible assets 3.7 3.7
Trade/domain names and other licenses    
Acquired Finite-Lived Intangible Assets [Line Items]    
Finite-lived trade/domain names, gross amount 7.7 4.1
Finite-lived intangible assets, accumulated amortization (3.8) (3.2)
Total intangible assets subject to amortization 3.9 0.9
Software programs/platforms    
Acquired Finite-Lived Intangible Assets [Line Items]    
Finite-lived software programs/platforms, gross amount 2.4 4.9
Finite-lived intangible assets, accumulated amortization (1.8) (4.1)
Total intangible assets subject to amortization 0.6 0.8
Client and supplier base    
Acquired Finite-Lived Intangible Assets [Line Items]    
Finite-lived customer base, gross amount 25.3 37.7
Finite-lived intangible assets, accumulated amortization (13.4) (25.6)
Total intangible assets subject to amortization $ 11.9 $ 12.1