Benefit Plans - Additional Information (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2023	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Percent of total assets domestic plans		65.00%
Cost of the savings incentive plan		$ 156	$ 178	$ 153
Fixed Income Funds
Defined Benefit Plan Disclosure [Line Items]
Company's Target allocation percentage for asset mix		45.00%
Diversified
Defined Benefit Plan Disclosure [Line Items]
Company's Target allocation percentage for asset mix		21.00%
Equity securities
Defined Benefit Plan Disclosure [Line Items]
Company's Target allocation percentage for asset mix		34.00%
Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value		$ 2,129	2,242	3,222
Pension plan projected benefit obligations		2,617	2,634	$ 3,889
Employer contribution		62	198
Foreign Plans | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value		748	705
Pension plan projected benefit obligations		$ 833	772
Percent of total plan assets foreign plans		35.00%
Foreign Plans | Pension Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value		$ 173	190
United States | Pension Plans
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value		1,382	1,537
United States | Pension Plans | Subsequent Event
Defined Benefit Plan Disclosure [Line Items]
Employer contribution	$ 150
United States | Pension Plans | Equity securities
Defined Benefit Plan Disclosure [Line Items]
Pension plan assets at fair value		469	469
United States | Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Pension plan projected benefit obligations		$ 92	$ 101