COLLATERALIZED AGREEMENTS AND FINANCINGS, Schedule of Offsetting Transactions (Details) - USD ($) $ in Millions	Mar. 31, 2022	Sep. 30, 2021
Reverse repurchase agreements
Gross amounts of recognized assets/liabilities	$ 221	$ 279
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	221	279
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(221)	(279)
Net amounts	0	0
Securities borrowed
Gross amounts of recognized assets/liabilities	350	201
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	350	201
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(337)	(195)
Net amounts	13	6
Gross amounts of recognized assets/liabilities	571	480
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	571	480
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(558)	(474)
Net amounts	13	6
Repurchase agreements
Gross amounts of recognized assets/liabilities	140	205
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	140	205
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(140)	(205)
Net amounts	0	0
Securities loaned
Gross amounts of recognized assets/liabilities	285	72
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	285	72
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(260)	(68)
Net amounts	25	4
Gross amounts of recognized assets/liabilities	425	277
Gross amounts offset on the Condensed Consolidated Statements of Financial Condition	0	0
Net amounts presented on the Condensed Consolidated Statements of Financial Condition	425	277
Gross amounts not offset on the Condensed Consolidated Statements of Financial Condition	(400)	(273)
Net amounts	$ 25	$ 4