Pension and Other Postretirement Benefits - Net Periodic Pension and Other Postretirement Plan Cost (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Investment income (expense) and other	Investment income (expense) and other	Investment income (expense) and other
U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 0	$ 0	$ 0
Interest cost	24	25	28
Expected return on assets	(80)	(70)	(72)
Amortization of actuarial (gain) loss	0	3	6
Settlement (gain) loss	10	(1)	8
Total net periodic benefit cost	(46)	(43)	(30)
Non-U.S. Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	3	4	4
Interest cost	10	10	10
Expected return on assets	(18)	(17)	(15)
Amortization of actuarial (gain) loss	0	4	2
Settlement (gain) loss	0	2	0
Total net periodic benefit cost	$ (5)	$ 3	$ 1