Accumulated Other Comprehensive Income (Loss) - Changes in Each Component of AOCI, Net of Tax (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 1,032	$ 1,090
Ending Balance	1,407	1,032
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(429)	(265)
Other comprehensive income (loss) before reclassifications	80	(208)
Amounts reclassified from AOCI	(4)	29
Less: Other comprehensive income (loss) attributable to noncontrolling interests		(15)
Ending Balance	(353)	(429)
Pension and Other Postretirement Benefit Liability Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(10)	(24)
Other comprehensive income (loss) before reclassifications	3	12
Amounts reclassified from AOCI	(2)	2
Ending Balance	(9)	(10)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(439)	(289)
Other comprehensive income (loss) before reclassifications	83	(196)
Amounts reclassified from AOCI	(6)	31
Less: Other comprehensive income (loss) attributable to noncontrolling interests		(15)
Ending Balance	$ (362)	$ (439)