Shareholders' Equity - Changes in Certain Components of Shareholders' Equity (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Beginning balance	$ 25,796
Net income	281	$ 509
Ending balance	$ 25,332
Dividends per Common Share (USD per share)	$ 0.95	$ 0.91
Common Stock  Issued at Par Value
Beginning balance	$ 371	$ 365
Ending balance	371	365
Capital in Excess of Par Value
Beginning balance	19,720	19,553
Issuance of shares under employee and other plans, net	(62)	(52)
Share-based compensation	83	89
Ending balance	19,741	19,590
Retained Earnings
Beginning balance	15,535	15,157
Net income	281	509
Common dividends	(275)	(259)
Preferred dividends		(23)
Ending balance	15,540	15,384
Deferred Compensation
Beginning balance	24	23
Ending balance	24	24
Treasury Stock
Beginning balance	$ (8,305)	$ (8,330)
Beginning balance (shares)	(80,203)	(81,283)
Issuance of shares under employee and other plans, net	$ (20)	$ (3)
Common stock issued for share-based compensation and other plans, net (in shares)	647	556
Common stock held in trusts, net (in shares)	(19)	(11)
Repurchase of common stock	$ (503)
Repurchase of common stock (in shares)	(2,118)
Ending balance	$ (8,828)	$ (8,333)
Ending balance (shares)	(81,692)	(80,738)