DERIVATIVE ASSETS AND DERIVATIVE LIABILITIES, Derivative Asset and Liability Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Derivative assets
Derivative assets	$ 307	$ 349
Counterparty netting	(92)	(86)
Cash collateral netting	(147)	(160)
Total amounts offset	(239)	(246)
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	68	103
Financial instruments	(1)	(5)
Net amount	67	98
Derivative liabilities
Derivative liabilities	313	347
Counterparty netting	(92)	(86)
Cash collateral netting	(31)	(37)
Netting adjustment	(123)	(123)
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	190	224
Financial instruments	0	0
Net amount	190	224
Notional amount	24,173	25,159
Derivatives not designated as hedging instruments
Derivative assets
Derivative assets	306	342
Derivative liabilities
Derivative liabilities	313	347
Notional amount	22,081	22,683
Derivatives not designated as hedging instruments | Interest rate
Derivative assets
Derivative assets	306	336
Derivative liabilities
Derivative liabilities	309	346
Notional amount	20,446	20,629
Derivatives not designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	0	2
Derivative liabilities
Derivative liabilities	2	1
Notional amount	539	949
Derivatives not designated as hedging instruments | Other
Derivative assets
Derivative assets	0	4
Derivative liabilities
Derivative liabilities	2	0
Notional amount	1,096	1,105
Derivatives designated as hedging instruments
Derivative assets
Derivative assets	1	7
Derivative liabilities
Derivative liabilities	0	0
Notional amount	2,092	2,476
Derivatives designated as hedging instruments | Interest rate
Derivative assets
Derivative assets	0	2
Derivative liabilities
Derivative liabilities	0	0
Notional amount	850	1,250
Derivatives designated as hedging instruments | Foreign exchange
Derivative assets
Derivative assets	1	5
Derivative liabilities
Derivative liabilities	0	0
Notional amount	$ 1,242	$ 1,226