Financial Instruments (Gains and Losses Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Summary of Net Investment Hedge Activity [Abstract]
Tax effects	$ 32.8	$ (71.2)	$ (2.8)
Net Amount Recognized in OCI	151.1	(1,230.5)	267.3
Summary of Cash Flow Hedge Activity [Abstract]
Tax effects	(48.6)	63.9	9.0
Net Amount Recognized in OCI	369.2	(120.3)	$ 3.3
Net Investment Hedges
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(145.1)	331.9
Tax effects	35.8	(82.1)
Net Amount Recognized in OCI	(109.3)	249.8
Net Investment Hedges | Forward exchange contracts
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(39.3)	89.8
Net Investment Hedges | Foreign currency debt
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(99.9)	229.6
Net Investment Hedges | Cross currency interest rate swaps
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(5.9)	12.5
Cash Flow Hedges
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	417.8	(184.2)
Tax effects	(48.6)	63.9
Net Amount Recognized in OCI	369.2	(120.3)
Cash Flow Hedges | Forward exchange contracts
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	111.1	(310.2)
Cash Flow Hedges | Forward exchange contracts, excluded components
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	(18.7)	2.8
Cash Flow Hedges | Other
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	$ 325.4	$ 123.2