DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Asset and Liability Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Sep. 30, 2023
Derivative assets
Derivative assets	$ 400	$ 526
Counterparty netting	(33)	(29)
Cash collateral netting	(282)	(232)
Total amounts offset	(315)	(261)
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	85	265
Financial instruments	(9)	(131)
Net amount	76	134
Derivative liabilities
Derivative liabilities	436	578
Counterparty netting	(33)	(29)
Cash collateral netting	(49)	(59)
Total amounts offset	(82)	(88)
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	354	490
Financial instruments	0	0
Net amount	354	490
Notional amount	24,033	22,441
Derivatives not designated as hedging instruments
Derivative assets
Derivative assets	396	513
Derivative liabilities
Derivative liabilities	435	578
Notional amount	21,580	20,069
Derivatives not designated as hedging instruments | Interest rate
Derivative assets
Derivative assets	396	509
Derivative liabilities
Derivative liabilities	434	576
Notional amount	19,593	18,270
Derivatives not designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	0	4
Derivative liabilities
Derivative liabilities	1	2
Notional amount	975	1,191
Derivatives not designated as hedging instruments | Other
Derivative assets
Derivative assets	0	0
Derivative liabilities
Derivative liabilities	0	0
Notional amount	1,012	608
Derivatives designated as hedging instruments
Derivative assets
Derivative assets	4	13
Derivative liabilities
Derivative liabilities	1	0
Notional amount	2,453	2,372
Derivatives designated as hedging instruments | Interest rate
Derivative assets
Derivative assets	4	8
Derivative liabilities
Derivative liabilities	0	0
Notional amount	1,250	1,200
Derivatives designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	0	5
Derivative liabilities
Derivative liabilities	1	0
Notional amount	$ 1,203	$ 1,172