COLLATERALIZED AGREEMENTS AND FINANCINGS, Schedule of Offsetting Transactions (Details) - USD ($) $ in Millions	Jun. 30, 2024	Sep. 30, 2023
Reverse repurchase agreements
Gross amounts of recognized assets/liabilities	$ 311	$ 187
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	311	187
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(311)	(187)
Net amounts	0	0
Securities borrowed
Gross amounts of recognized assets/liabilities	259	231
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	259	231
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(249)	(224)
Net amounts	10	7
Gross amounts of recognized assets/liabilities	570	418
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	570	418
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(560)	(411)
Net amounts	10	7
Repurchase agreements
Gross amounts of recognized assets/liabilities	374	157
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	374	157
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(374)	(157)
Net amounts	0	0
Securities loaned
Gross amounts of recognized assets/liabilities	780	180
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	780	180
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(750)	(173)
Net amounts	30	7
Gross amounts of recognized assets/liabilities	1,154	337
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts included in the Condensed Consolidated Statements of Financial Condition	1,154	337
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(1,124)	(330)
Net amounts	$ 30	$ 7