Debt - Other Debt and Other Items (Details) - Other Debt - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Unsecured
Debt Instrument [Line Items]
Current borrowing capacity	$ 367.4
Standby Letters of Credit
Debt Instrument [Line Items]
Outstanding standby letters of credit	$ 899.4	$ 934.5

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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+ Details