Supplemental Financial Information - Trade Receivables, Allowances for Doubtful Accounts and Cash Discounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2021
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 81	$ 91	$ 88
Additions charged to costs and expenses	109	77	101
Deductions and other	(110)	(87)	(97)
Ending Balance	81	81	91
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	65	73	76
Additions charged to costs and expenses	9	4	17
Deductions and other	(10)	(12)	(20)
Ending Balance	65	65	73
Allowance for Cash Discounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	16	18	12
Additions charged to costs and expenses	100	73	84
Deductions and other	(100)	(75)	(77)
Ending Balance	$ 16	$ 16	$ 18