Supplemental Information (Other Noncurrent Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Disclosure Text Block Supplement [Abstract]
Asset retirement obligations	$ 328.8	$ 322.9
Contract liabilities	283.6	290.0
Pension benefits	266.1	236.1
Postretirement benefits	5.0	8.9
Contingencies related to uncertain tax positions	120.7	98.5
Environmental liabilities	71.8	67.2
Derivative instruments	57.7	56.0
Long-term accrued income taxes related to U.S. tax reform	0.0	60.8
Other	214.4	210.1
Other noncurrent liabilities	$ 1,348.1	$ 1,350.5

Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable after twelve months or beyond the next operating cycle if longer.

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Noncurrent portion of the carrying amount of a liability for an asset retirement obligation. An asset retirement obligation is a legal obligation associated with the disposal or retirement of a tangible long-lived asset that results from the acquisition, construction or development, or the normal operations of a long-lived asset, except for certain obligations of lessees.

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Amount of obligation to transfer good or service to customer for which consideration has been received or is receivable, classified as noncurrent.

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Amount of liability, recognized in statement of financial position, for defined benefit pension plan, classified as noncurrent. Excludes other postretirement benefit plan.

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled after one year or the normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

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Amount recognized for uncertainty in income taxes classified as noncurrent.

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Amount of liability, recognized in statement of financial position, for defined benefit other postretirement plan, classified as noncurrent. Excludes pension plan.

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Obligations not otherwise itemized or categorized in the footnotes to the financial statements that are expected to be paid after one year (or the normal operating cycle, if longer), from the balance sheet date.

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Amount of tax liability from transition tax on accumulated earnings of controlled foreign corporation deemed repatriated pursuant to Tax Cuts and Jobs Act, classified as noncurrent.

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