DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Gain (Loss) Recognized in AOCI (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedges	$ (4)	$ (19)	$ (37)	$ (49)
Total gains/(losses) in AOCI, net of taxes	(25)	(31)	(19)	(35)
Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Cash flow hedges	(4)	(19)	(37)	(49)
Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Net investment hedges	$ (21)	$ (12)	$ 18	$ 14