Derivative Instruments and Hedging Activities - Derivatives Gains and Losses (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Total		$ (33)	$ (34)	$ (3)
Foreign currency exchange derivatives | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) on foreign currency exchange derivatives not designated as hedging instrument		0	(4)	(4)
Foreign currency exchange derivatives | Net financing charges
Derivative Instruments, Gain (Loss) [Line Items]
Pre-tax gain (loss) on foreign currency exchange derivatives not designated as hedging instrument		(33)	(30)	1
Foreign currency exchange derivatives | Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedges on foreign currency exchange derivatives		8	29	(37)
Foreign currency exchange derivatives | Cash flow hedging | Cost of sales
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedges on foreign currency exchange derivatives, reclassified from AOCI	$ (2)	$ 6	$ 2	$ (16)