Benefit Plans - Net Pension and Other Postretirement Cost (Detail) - Pension Plans - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 134	$ 150	$ 153
Interest cost	77	71	84
Expected return on plan assets	(187)	(174)	(188)
Amortization of prior service credit	(15)	(16)	(13)
Amortization of loss	61	97	97
Curtailment/settlement loss	73	9	4
Net pension cost	143	137	137
Foreign Plans
Defined Benefit Plan Disclosure [Line Items]
Net pension cost	$ 20	$ 41	$ 41