Short-Term Borrowings And Lines Of Credit (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Apr. 30, 2014
Short Term Borrowings And Lines Of Credit [Line Items]
Current maturities of long-term debt	$ 270	$ 267
Commercial paper	592	2,317
Total	$ 862	$ 2,584
Interest rate for weighted-average short-term borrowings at year end	1.10%	0.50%
Five-year revolving credit facility [Member]
Short Term Borrowings And Lines Of Credit [Line Items]
Line of credit facility, maximum borrowing capacity	$ 3,500
Four-year revolving credit facility [Member]
Short Term Borrowings And Lines Of Credit [Line Items]
Line of credit facility, maximum borrowing capacity			$ 2,750