Pension and Other Postretirement Benefits - Change in Pension Benefit Obligations, Plan Assets, Funded Status and Amounts Recognized in the Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
U.S. Plans
Change in pension benefit obligation:
Benefit obligation at beginning of period	$ 877	$ 920
Service cost	0	0	$ 0
Interest cost	24	25	28
Actuarial (gain) loss	(185)	(8)
Benefit payments	(53)	(60)
Foreign currency exchange rate changes	0	0
Benefit obligation at end of period	663	877	920
Accumulated benefit obligation	663	877
Change in plan assets:
Fair value of plan assets at beginning of period	1,288	1,142
Actual return on plan assets	(275)	205
Company contribution	0	1
Benefit payments	(53)	(60)
Foreign currency exchange rate changes	0	0
Fair value of plan assets at end of period	960	1,288	1,142
Funded status at end of period	297	411
Recognized in consolidated balance sheets:
Non-current asset	302	417
Current liability	(1)	(1)
Non-current liability	(4)	(5)
Funded status at end of period	297	411
Non-U.S. Plans
Change in pension benefit obligation:
Benefit obligation at beginning of period	520	563
Service cost	3	4	4
Interest cost	10	10	10
Actuarial (gain) loss	(174)	(53)
Benefit payments	(14)	(28)
Foreign currency exchange rate changes	(67)	24
Benefit obligation at end of period	278	520	563
Accumulated benefit obligation	278	520
Change in plan assets:
Fair value of plan assets at beginning of period	548	525
Actual return on plan assets	(151)	9
Company contribution	20	21
Benefit payments	(14)	(28)
Foreign currency exchange rate changes	(76)	21
Fair value of plan assets at end of period	327	548	$ 525
Funded status at end of period	49	28
Recognized in consolidated balance sheets:
Non-current asset	51	30
Current liability	0	0
Non-current liability	(2)	(2)
Funded status at end of period	$ 49	$ 28