Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Allowance for credit losses
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 19	$ 19	$ 20
Additions Charged to Cost and Expenses	10	5	5
Deductions	(3)	(5)	(6)
Balance at End of period	26	19	19
Reserves for sales returns
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	19	19	23
Additions Charged to Cost and Expenses	37	39	52
Deductions	(36)	(39)	(56)
Balance at End of period	20	19	19
Allowance for deferred tax asset
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	25	29	38
Additions Charged to Cost and Expenses	1	1	2
Deductions	(1)	(5)	(11)
Balance at End of period	$ 25	$ 25	$ 29