Debt and Financing Arrangements - Net Financing Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2022
Debt Disclosure [Abstract]
Interest expense, net of capitalized interest costs	$ 191	$ 186	$ 161
Banking fees and debt issuance cost amortization	18	20	22
Interest income	(28)	(22)	(9)
Premium paid on repurchase of debt	0	7	38
Derivative loss on Yanfeng transaction	0	0	3
Net foreign exchange	8	4	0
Net financing charges	$ 189	$ 195	$ 215