SEGMENT INFORMATION, Information Concerning Operations (Details) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) segment	Jun. 30, 2022 USD ($)	Sep. 30, 2022 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment			5
Revenues:
Total net revenues	$ 2,907	$ 2,718	$ 8,566	$ 8,172
Pre-tax income
Total pre-tax income	486	415	1,695	1,406
Insurance settlement			32
Net interest income (expense):
Net interest income	601	314	1,818	706
Total assets:
Total assets	77,633		77,633		$ 80,951
Goodwill:
Goodwill	1,443		1,443		1,422
Operating segments | Private Client Group
Revenues:
Total net revenues	2,182	1,958	6,389	5,719
Pre-tax income
Total pre-tax income	411	251	1,286	659
Net interest income (expense):
Net interest income	89	58	264	122
Total assets:
Total assets	12,287		12,287		17,770
Goodwill:
Goodwill	570		570		550
Operating segments | Capital Markets
Revenues:
Total net revenues	276	383	873	1,410
Pre-tax income
Total pre-tax income	(34)	61	(84)	349
Net interest income (expense):
Net interest income	0	3	1	8
Total assets:
Total assets	2,926		2,926		3,951
Goodwill:
Goodwill	275		275		274
Operating segments | Asset Management
Revenues:
Total net revenues	226	228	649	698
Pre-tax income
Total pre-tax income	89	93	251	303
Net interest income (expense):
Net interest income	2	1	7	1
Total assets:
Total assets	545		545		556
Goodwill:
Goodwill	69		69		69
Operating segments | Bank
Revenues:
Total net revenues	514	276	1,562	656
Pre-tax income
Total pre-tax income	66	74	293	259
Net interest income (expense):
Net interest income	497	270	1,518	636
Total assets:
Total assets	59,506		59,506		56,737
Goodwill:
Goodwill	529		529		529
Operating segments | Other
Revenues:
Total net revenues	15	(21)	34	(54)
Pre-tax income
Total pre-tax income	(46)	(64)	(51)	(164)
Net interest income (expense):
Net interest income	13	(18)	28	(61)
Total assets:
Total assets	2,369		2,369		$ 1,937
Intersegment eliminations
Revenues:
Total net revenues	$ (306)	$ (106)	$ (941)	$ (257)