Commitments and Contingencies - Schedule of Loss Contingencies by Contingency (Details) - USD ($) $ in Millions	Mar. 31, 2026	Sep. 30, 2025
Loss Contingencies [Line Items]
Reserve for environmental liabilities, current	$ 23	$ 27
Reserve for environmental liabilities, noncurrent	152	160
Total reserves for environmental liabilities	175	187
Total asbestos-related liabilities	386	387
Total asbestos-related assets	324	339
Net asbestos-related liabilities	62	48
Restricted
Insurance receivables for asbestos-related liabilities	42	44
Total self-insured liabilities	438	414
Asbestos Issue
Loss Contingencies [Line Items]
Total asbestos-related assets	282	295
Restricted
Cash	6	5
Investments	276	290
Other current liabilities
Loss Contingencies [Line Items]
Total asbestos-related liabilities	58	58
Restricted
Total self-insured liabilities	84	87
Other noncurrent liabilities
Loss Contingencies [Line Items]
Total asbestos-related liabilities	328	329
Restricted
Total self-insured liabilities	316	289
Other current assets
Loss Contingencies [Line Items]
Total asbestos-related assets	14	13
Other noncurrent assets
Loss Contingencies [Line Items]
Total asbestos-related assets	310	326
Accrued compensation and benefits
Restricted
Total self-insured liabilities	$ 38	$ 38

Estimated Asbestos Related Net Liability On A Discounted Basis

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