Financial Instruments (Gains and Losses Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Summary of Net Investment Hedge Activity [Abstract]
Tax effects	$ 33.0	$ 32.8	$ (71.2)
Net Amount Recognized in OCI	381.5	151.1	(1,230.5)
Summary of Cash Flow Hedge Activity [Abstract]
Tax effects	(10.7)	(48.6)	63.9
Net Amount Recognized in OCI	(159.5)	369.2	$ (120.3)
Net Investment Hedges
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(131.9)	(145.1)
Tax effects	32.2	35.8
Net Amount Recognized in OCI	(99.7)	(109.3)
Net Investment Hedges \| Forward exchange contracts
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(23.7)	(39.3)
Net Investment Hedges \| Foreign currency debt
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(107.4)	(99.9)
Net Investment Hedges \| Cross currency interest rate swaps
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(0.8)	(5.9)
Cash Flow Hedges
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	(148.8)	417.8
Tax effects	(10.7)	(48.6)
Net Amount Recognized in OCI	(159.5)	369.2
Cash Flow Hedges \| Forward exchange contracts
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	142.8	111.1
Cash Flow Hedges \| Forward exchange contracts, excluded components
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	(31.2)	(18.7)
Cash Flow Hedges \| Other
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	$ (260.4)	$ 325.4

Amount after tax, before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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