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	$ 219	$ 240	$ 335
Banking and other fees and amortization of bond costs, premiums and discounts	25	26	28
Loss on Extinguishment of Debt	0	0	60
Interest income	(9)	(23)	(61)
Net foreign exchange results for financing activities	(29)	(12)	(12)
Net financing charges	$ 206	$ 231	$ 350