Accumulated Other Comprehensive Income (Loss) - Changes in Each Component of AOCI, Net of Tax (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	$ 1,090	$ 814
Ending Balance	1,032	1,090
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(265)	(307)
Other comprehensive income (loss) before reclassifications	(208)	52
Amounts reclassified from AOCI	29	(3)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(15)	7
Ending Balance	(429)	(265)
Pension and Other Postretirement Benefit Liability Adjustment [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(24)	(44)
Other comprehensive income (loss) before reclassifications	12	20
Amounts reclassified from AOCI	2
Ending Balance	(10)	(24)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning Balance	(289)	(351)
Other comprehensive income (loss) before reclassifications	(196)	72
Amounts reclassified from AOCI	31	(3)
Less: Other comprehensive income (loss) attributable to noncontrolling interests	(15)	7
Ending Balance	$ (439)	$ (289)