Note 9. Derivative Instruments and Hedging Activities Derivatives Gains and Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2015
Derivative Instruments, Gain (Loss) [Line Items]
Unrealized Gain (Loss) on Foreign Currency Derivatives, Net, before Tax	$ 3	$ 34	$ 8
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	19	7	15
Derivatives used in Net Investment Hedge, Increase (Decrease), Gross of Tax	(61)	(24)	16
Amount of Ineffectiveness on Net Investment Hedges	0
Cost of Sales [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net	(13)	31	22
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	(20)	10	1
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	36	(3)	14
Selling, General and Administrative Expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments	$ 3	$ 0	$ 0