Short-Term Borrowings And Lines Of Credit (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	May 31, 2018
Short Term Borrowings And Lines Of Credit [Line Items]
Current maturities of long-term debt	$ 322	$ 515
Commercial paper	838	929
Total	$ 1,160	$ 1,444
Interest rate for weighted-average short-term borrowings at year end	0.10%	2.10%
Line of credit facility, maximum borrowing capacity	$ 3,500		$ 3,500
Line of credit facility, expiration period	5 years