Employee Benefit Plans - Change in Projected Benefit Obligations and Change in Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
Change in Plan Assets:
Fair value of plan assets at beginning of year	$ 135
Fair value of plan assets at end of year	144	$ 135
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	$ 2	3
(Gain) loss from changes in actuarial assumptions and plan experience		$ (1)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement and Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense)	Other income (expense)
Benefit obligation at end of year	$ 2	$ 2	$ 3
Change in Plan Assets:
Funded status	(2)	(2)
Recognized asset (liability)	(2)	(2)
Pension Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	133	221
Service cost	3	4	6
Interest cost	$ 7	$ 4	3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense)	Other income (expense)
Plan participants’ contribution	$ 1	$ 1
Foreign currency exchange rate changes	6	(27)
(Gain) loss from changes in actuarial assumptions and plan experience	(4)	(43)
Benefits paid	(5)	(9)
Settlements or curtailments	$ (2)	$ (2)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement and Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense)	Other income (expense)
Divestiture of a business		$ (16)
Benefit obligation at end of year	$ 139	133	221
Change in Plan Assets:
Fair value of plan assets at beginning of year	135	217
Actual return on plan assets	4	(35)
Employer contribution	4	5
Plan participants’ contribution	1	1
Foreign currency exchange rate changes	7	(24)
Benefits paid	(5)	(9)
Settlements or curtailments	(2)	(2)
Divestiture of a business		(18)
Fair value of plan assets at end of year	144	135	217
Funded status	5	2
Recognized asset (liability)	5	2
Postretirement Benefits [Member] | U.S. Defined Benefit Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	16	25
Interest cost	1
(Gain) loss from changes in actuarial assumptions and plan experience	(1)	(4)
Benefits paid	$ (2)	(3)
Settlements or curtailments		$ (2)
Defined Benefit Plan, Net Periodic Benefit (Cost) Credit, Settlement and Curtailment Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense)	Other income (expense)
Benefit obligation at end of year	$ 14	$ 16	25
Change in Plan Assets:
Employer contribution	2	5
Benefits paid	(2)	(3)
Settlements or curtailments		(2)
Funded status	(14)	(16)
Recognized asset (liability)	(14)	(16)
Postretirement Benefits [Member] | Foreign Plans [Member]
Change in Benefit Obligations:
Benefit obligation at beginning of year	13	19
Interest cost	$ 1	$ 1	1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Other income (expense)	Other income (expense)
Foreign currency exchange rate changes	$ 1	$ (2)
(Gain) loss from changes in actuarial assumptions and plan experience	(3)	(5)
Benefits paid	(1)
Benefit obligation at end of year	11	13	$ 19
Change in Plan Assets:
Employer contribution	1
Benefits paid	(1)
Funded status	(11)	(13)
Recognized asset (liability)	$ (11)	$ (13)