Debt and Financing Arrangements - Components of Net Financing Charges (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Debt Disclosure [Abstract]
Interest expense, net of capitalized interest costs	$ 55	$ 59
Banking fees and bond cost amortization	5	8
Interest income	(2)	(3)
Net foreign exchange results for financing activities	(5)	(5)
Net financing charges	$ 53	$ 59