DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Income Statement Location (Details) - Derivatives not designated as hedging instruments - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Principal transactions/other revenues | Interest rate
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative asset or liability	$ 7	$ 6	$ 10	$ 10
Other revenues | Foreign exchange
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative asset or liability	(2)	(4)	(3)	(30)
Principal transactions | Other
Derivative Instruments, Gain (Loss) [Line Items]
Change in fair value of derivative asset or liability	$ (2)	$ (2)	$ 1	$ 2