Financial Instruments and Risk Management (Schedule of Gains and Losses on Derivative Instruments) (Details) - FX contract - USD ($) $ in Millions		12 Months Ended
		Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Designated as hedging instrument | Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Gain recognized in OCI	[1]	$ 1.1	$ 19.2	$ 3.1
Gain (loss) reclassified from AOCI into income (effective portion)		$ 8.0	$ 11.2	$ (3.2)
Gain (loss) reclassified from AOCI into income - financial statement location	[1],[2]	Nonoperating Income (Expense)	Nonoperating Income (Expense)	Nonoperating Income (Expense)
Not designated as hedging instrument
Derivative Instruments, Gain (Loss) [Line Items]
Change in estimate of fair value of foreign currency contracts		$ 3.0	$ 8.2	$ 2.3
Gain (loss) on fair value hedges - financial statement location	[2]	Nonoperating Income (Expense)	Nonoperating Income (Expense)	Nonoperating Income (Expense)

[1] Each of these derivative instruments had a high correlation to the underlying exposure being hedged for the periods indicated and had been deemed highly effective in offsetting associated risk.

[2] ain (loss) was recorded in Other expense (income), net.