Debt and Financing Arrangements - Net Financing Charges (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Debt Disclosure [Abstract]
Interest expense, net of capitalized interest costs	$ 207	$ 216	$ 167
Banking fees and debt issuance cost amortization	32	18	26
Interest income	(7)	(11)	(11)
Premium paid on repurchase of debt	49	0	0
Derivative loss on Yanfeng transaction	30	0	0
(Gain) on extinguishment of debt	0	(3)	0
Net financing charges	$ 311	$ 220	$ 182