DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Asset and Liability Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Derivative assets
Derivative assets	$ 526	$ 536
Counterparty netting	(29)	(35)
Cash collateral netting	(232)	(313)
Total amounts offset	(261)	(348)
Net amounts presented on the Consolidated Statements of Financial Condition	265	188
Financial instruments	(131)	(60)
Net amount	134	128
Derivative liabilities
Derivative liabilities	578	595
Counterparty netting	(29)	(35)
Cash collateral netting	(59)	(30)
Total amounts offset	(88)	(65)
Net amounts presented on the Consolidated Statements of Financial Condition	490	530
Financial instruments	0	(52)
Net amount	490	478
Notional amount	22,441	19,618
Derivatives not designated as hedging instruments
Derivative assets
Derivative assets	513	518
Derivative liabilities
Derivative liabilities	578	595
Notional amount	20,069	17,476
Derivatives not designated as hedging instruments | Interest rate - other
Derivative assets
Derivative assets	509	462
Derivative liabilities
Derivative liabilities	576	535
Notional amount	18,270	14,647
Derivatives not designated as hedging instruments | Interest rate - matched book
Derivative assets
Interest rate - matched book	0	52
Derivative liabilities
Derivative liabilities - matched book	0	52
Notional amount	0	1,340
Derivatives not designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	4	4
Derivative liabilities
Derivative liabilities	2	5
Notional amount	1,191	958
Derivatives not designated as hedging instruments | Other
Derivative assets
Derivative assets	0	0
Derivative liabilities
Derivative liabilities	0	3
Notional amount	608	531
Derivatives designated as hedging instruments
Derivative assets
Derivative assets	13	18
Derivative liabilities
Derivative liabilities	0	0
Notional amount	2,372	2,142
Derivatives designated as hedging instruments | Interest rate - other
Derivative assets
Derivative assets	8	12
Derivative liabilities
Derivative liabilities	0	0
Notional amount	1,200	1,050
Derivatives designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	5	6
Derivative liabilities
Derivative liabilities	0	0
Notional amount	$ 1,172	$ 1,092