Commitments and Contingencies - Schedule of Loss Contingencies by Contingency (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Loss Contingencies [Line Items]
Reserve for environmental liabilities, current	$ 38	$ 66
Reserve for environmental liabilities, noncurrent	214	220
Total reserves for environmental liabilities	252	286
Total asbestos-related liabilities	421	438
Total asbestos-related assets	317	300
Net asbestos-related liabilities	104	138
Restricted
Insurance receivables for asbestos-related liabilities	51	55
Total self-insured liabilities	331	341
Insurance receivables, current	10	10
Insurance receivables, noncurrent	20	20
Total insurance receivables	30	30
Asbestos Issue
Loss Contingencies [Line Items]
Total asbestos-related assets	266	245
Restricted
Cash	26	6
Investments	240	239
Other current liabilities
Loss Contingencies [Line Items]
Total asbestos-related liabilities	58	58
Restricted
Total self-insured liabilities	77	89
Other noncurrent liabilities
Loss Contingencies [Line Items]
Total asbestos-related liabilities	363	380
Restricted
Total self-insured liabilities	232	230
Other current assets
Loss Contingencies [Line Items]
Total asbestos-related assets	34	37
Other noncurrent assets
Loss Contingencies [Line Items]
Total asbestos-related assets	283	263
Accrued compensation and benefits
Restricted
Total self-insured liabilities	$ 22	$ 22