DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Asset and Liability Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020
Derivative assets
Derivative assets	$ 342	$ 573
Counterparty netting	(46)	(40)
Cash collateral netting	(41)	(95)
Total amounts offset	(87)	(135)
Net amounts presented on the Consolidated Statements of Financial Condition	255	438
Financial instruments	(205)	(349)
Net amount	50	89
Derivative liabilities
Derivative liabilities	316	505
Counterparty netting	(46)	(40)
Cash collateral netting	(42)	(72)
Total amounts offset	(88)	(112)
Net amounts presented on the Consolidated Statements of Financial Condition	228	393
Financial instruments	(193)	(333)
Net amount	35	60
Notional amount	19,989	24,309
Derivatives not designated as hedging instruments
Derivative assets
Derivative assets	340	573
Derivative liabilities
Derivative liabilities	316	502
Notional amount	18,200	22,593
Derivatives not designated as hedging instruments | Interest rate - matched book
Derivative assets
Interest rate - matched book	193	333
Derivative liabilities
Interest rate - matched book	193	333
Notional amount	1,736	2,174
Derivatives not designated as hedging instruments | Interest rate - other
Derivative assets
Derivative assets	144	240
Derivative liabilities
Derivative liabilities	122	161
Notional amount	15,087	19,206
Derivatives not designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	3	0
Derivative liabilities
Derivative liabilities	0	2
Notional amount	826	605
Derivatives not designated as hedging instruments | Other
Derivative assets
Derivative assets	0	0
Derivative liabilities
Derivative liabilities	1	6
Notional amount	551	608
Derivatives designated as hedging instruments
Derivative assets
Derivative assets	2	0
Derivative liabilities
Derivative liabilities	0	3
Notional amount	1,789	1,716
Derivatives designated as hedging instruments | Interest rate
Derivative assets
Derivative assets	0	0
Derivative liabilities
Derivative liabilities	0	0
Notional amount	850	850
Derivatives designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	2	0
Derivative liabilities
Derivative liabilities	0	3
Notional amount	$ 939	$ 866