Financial Instruments (Gains and Losses Recognized In Other Comprehensive Income) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Summary of Net Investment Hedge Activity [Abstract]
Tax effects	$ 61.4	$ 33.0	$ 32.8
Net Amount Recognized in OCI	(95.6)	381.5	151.1
Summary of Cash Flow Hedge Activity [Abstract]
Tax effects	1.8	(10.7)	(48.6)
Net Amount Recognized in OCI	40.0	(159.5)	$ 369.2
Net Investment Hedges
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(228.8)	(131.9)
Tax effects	54.8	32.2
Net Amount Recognized in OCI	(174.0)	(99.7)
Net Investment Hedges \| Forward exchange contracts
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	2.8	(23.7)
Net Investment Hedges \| Foreign currency debt
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	(232.8)	(107.4)
Net Investment Hedges \| Cross currency interest rate swaps
Summary of Net Investment Hedge Activity [Abstract]
Total Amount Recognized in OCI	1.2	(0.8)
Cash Flow Hedges
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	38.2	(148.8)
Tax effects	1.8	(10.7)
Net Amount Recognized in OCI	40.0	(159.5)
Cash Flow Hedges \| Forward exchange contracts
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	(56.4)	142.8
Cash Flow Hedges \| Forward exchange contracts, excluded components
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	(9.6)	(31.2)
Cash Flow Hedges \| Other
Summary of Cash Flow Hedge Activity [Abstract]
Total Amount Recognized in OCI	$ 104.2	$ (260.4)

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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