Debt - Summary of Interest Costs and Payments (Detail) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Debt Disclosure [Abstract]
Charged to operations	$ 398	$ 469	$ 528
Capitalized	46	44	43
Total interest costs	444	512	571
Interest paid, net of amounts capitalized	$ 390	$ 474	$ 515