Accumulated Other Comprehensive Income (Loss) ("AOCI") - Changes in Each Component of AOCI, Net of Tax (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 1,590	$ 1,407
Ending Balance	1,515	1,475
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(342)	(353)
Other comprehensive income (loss) before reclassifications	(104)	62
Amounts reclassified from AOCI		(1)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(7)	4
Ending Balance	(439)	(296)
Pension and Other Post-retirement Benefit Liability Adjustments [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(18)	(9)
Ending Balance	(18)	(9)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(360)	(362)
Other comprehensive income (loss) before reclassifications	(104)	62
Amounts reclassified from AOCI		(1)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(7)	4
Ending Balance	$ (457)	$ (305)