Income Taxes - Schedule of Income Before Taxes by Fiscal Year (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2023
Income Tax Disclosure [Abstract]
U.S.	$ 14,776	$ 14,537	$ 13,339
Non-U.S.	9,418	9,379	7,698
Income before income taxes	$ 24,194	$ 23,916	$ 21,037