The aggregate fair value of additional assets that would be required to be posted as collateral for derivative instruments with credit-risk-related contingent features if the credit-risk-related contingent features were triggered at the end of the reporting period.

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The aggregate fair value of assets that are already posted, at the end of the reporting period, as collateral for derivative instruments with credit-risk-related contingent features.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 815
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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The aggregate fair value amounts of derivative instruments that contain credit-risk-related contingent features that are in a net liability position at the end of the reporting period. For nonderivative instruments that are designated and qualify as hedging instruments, the fair value amounts are the carrying value of the nonderivative hedging instrument, including the adjustment for the foreign currency transaction gain (loss) on that instrument.

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Maximum amount of time remaining before foreign currency exchange rate derivatives mature or expire, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Nominal or face amount used to calculate payments on a nonderivative instrument.

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No definition available.

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Financial Instruments (Narrative) (Details) € in Millions	6 Months Ended		12 Months Ended
Financial Instruments (Narrative) (Details) € in Millions	Mar. 31, 2026 EUR (€)	Mar. 31, 2026 USD ($)	Sep. 30, 2025 EUR (€)	Sep. 30, 2025 USD ($)
Derivative [Line Items]
Net liability position of derivatives with credit risk-related contingent features		$ 91,300,000		$ 43,300,000
Collateral posted on liability positions with credit risk-related contingent features		0
Collateral amount that counterparties would be required to post		$ 259,600,000		174,000,000.0
Forward exchange contracts \| Cash flow hedges
Derivative [Line Items]
Maximum remaining maturity of foreign currency derivatives	2 years 3 months 18 days	2 years 3 months 18 days
Foreign currency debt \| Euro Denominated
Derivative [Line Items]
Notional amount included in designated foreign currency denominated debt	€ 3,142.0	$ 3,631,900,000	€ 3,188.1	$ 3,741,500,000