Commitments and Contingencies - Schedule of Loss Contingencies by Contingency (Details) - USD ($) $ in Millions	Jun. 30, 2026	Sep. 30, 2025
Loss Contingencies [Line Items]
Reserve for environmental liabilities, current	$ 21	$ 27
Reserve for environmental liabilities, noncurrent	148	160
Total reserves for environmental liabilities	169	187
Total asbestos-related liabilities	381	387
Total asbestos-related assets	350	339
Net asbestos-related liabilities	31	48
Restricted
Insurance receivables for asbestos-related liabilities	40	44
Total self-insured liabilities	452	414
Asbestos Issue
Loss Contingencies [Line Items]
Total asbestos-related assets	310	295
Restricted
Cash	7	5
Investments	303	290
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Restricted
Total self-insured liabilities	38	38
Balance Sheet Location [Axis]: us-gaap:OtherAssetsCurrent
Loss Contingencies [Line Items]
Total asbestos-related assets	15	13
Balance Sheet Location [Axis]: us-gaap:OtherAssetsNoncurrent
Loss Contingencies [Line Items]
Total asbestos-related assets	335	326
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesCurrent
Loss Contingencies [Line Items]
Total asbestos-related liabilities	58	58
Restricted
Total self-insured liabilities	89	87
Balance Sheet Location [Axis]: us-gaap:OtherLiabilitiesNoncurrent
Loss Contingencies [Line Items]
Total asbestos-related liabilities	323	329
Restricted
Total self-insured liabilities	$ 325	$ 289

Estimated Asbestos Related Net Liability On A Discounted Basis

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Insurable Liabilities

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

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