DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Assets and Liability Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2022	Sep. 30, 2021
Derivative assets
Derivative assets	$ 293	$ 342
Counterparty netting	(51)	(46)
Cash collateral netting	(59)	(41)
Total amounts offset	(110)	(87)
Derivative assets	183	255
Financial instruments	(128)	(205)
Net amount	55	50
Derivative liabilities
Derivative liabilities	334	316
Counterparty netting	(51)	(46)
Cash collateral netting	(12)	(42)
Total amounts offset	(63)	(88)
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	271	228
Financial instruments	(124)	(193)
Net amount	147	35
Notional amount	18,688	19,989
Derivatives not designated as hedging instruments
Derivative assets
Derivative assets	292	340
Derivative liabilities
Derivative liabilities	327	316
Notional amount	16,789	18,200
Derivatives not designated as hedging instruments | Interest rate - matched book
Derivative assets
Interest rate - matched book	124	193
Derivative liabilities
Interest rate - matched book	124	193
Notional amount	1,498	1,736
Derivatives not designated as hedging instruments | Interest rate - other
Derivative assets
Derivative assets	168	144
Derivative liabilities
Derivative liabilities	197	122
Notional amount	13,845	15,087
Derivatives not designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	0	3
Derivative liabilities
Derivative liabilities	6	0
Notional amount	876	826
Derivatives not designated as hedging instruments | Other
Derivative assets
Derivative assets	0	0
Derivative liabilities
Derivative liabilities	0	1
Notional amount	570	551
Derivatives designated as hedging instruments
Derivative assets
Derivative assets	1	2
Derivative liabilities
Derivative liabilities	7	0
Notional amount	1,899	1,789
Derivatives designated as hedging instruments | Interest rate - other
Derivative assets
Derivative assets	1	0
Derivative liabilities
Derivative liabilities	0	0
Notional amount	850	850
Derivatives designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	0	2
Derivative liabilities
Derivative liabilities	7	0
Notional amount	$ 1,049	$ 939