v3.24.1.u1
Fair Value Measurements - Schedule of Financial Instruments not Measured at Fair Value (Details) - USD ($)
$ in Millions
Mar. 31, 2024
Sep. 30, 2023
Financial Assets [Abstract]    
Other investments $ 261.3 $ 260.0
Financial Liability [Abstract]    
Debt 3,041.0 3,052.8
Carrying Value [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 3,300.2 3,686.4
Time deposits 10.1 9.9
Financial Liability [Abstract]    
Debt 3,041.0 3,052.8
Estimated Fair Value [Member] | Level 1 [Member]    
Financial Assets [Abstract]    
Cash and cash equivalents 3,300.2 3,686.4
Estimated Fair Value [Member] | Level 2 [Member]    
Financial Assets [Abstract]    
Time deposits 10.1 9.9
Financial Liability [Abstract]    
Debt 2,552.1 2,419.4
Equity securities [Member] | Carrying Value [Member]    
Financial Assets [Abstract]    
Other investments 251.2 250.1
Equity securities [Member] | Estimated Fair Value [Member] | Level 3 [Member]    
Financial Assets [Abstract]    
Other investments $ 251.2 $ 250.1