SEGMENT INFORMATION, Information Concerning Operations (Details) $ in Millions	12 Months Ended
	Sep. 30, 2022 USD ($) businessSegment	Sep. 30, 2021 USD ($)	Sep. 30, 2020 USD ($)
Segment Reporting [Abstract]
Number of operating segments | businessSegment	5
Net revenues:
Net revenues	$ 11,003	$ 9,760	$ 7,990
Pre-tax income/(loss):
Total pre-tax income	2,022	1,791	1,052
Net interest income (expense):
Net interest income	1,203	673	822
Total assets:
Aggregate assets	80,951	61,891
Goodwill and Intangible Assets:
Goodwill	1,422	660	466
Private Client Group
Goodwill and Intangible Assets:
Goodwill	550	417	277
Capital Markets
Goodwill and Intangible Assets:
Goodwill	274	174	120
Asset Management
Goodwill and Intangible Assets:
Goodwill	69	69	69
Bank
Goodwill and Intangible Assets:
Goodwill	529	0	0
Other
Net interest income (expense):
Net interest income	(68)	(88)	(58)
Operating segments | Private Client Group
Net revenues:
Net revenues	7,710	6,611	5,552
Pre-tax income/(loss):
Total pre-tax income	1,030	749	539
Net interest income (expense):
Net interest income	207	113	132
Total assets:
Aggregate assets	17,770	20,270
Operating segments | Capital Markets
Net revenues:
Net revenues	1,809	1,885	1,291
Pre-tax income/(loss):
Total pre-tax income	415	532	225
Net interest income (expense):
Net interest income	9	6	9
Total assets:
Aggregate assets	3,951	2,457
Operating segments | Asset Management
Net revenues:
Net revenues	914	867	715
Pre-tax income/(loss):
Total pre-tax income	386	389	284
Net interest income (expense):
Net interest income	2	0	1
Total assets:
Aggregate assets	556	476
Operating segments | Bank
Net revenues:
Net revenues	1,084	672	765
Pre-tax income/(loss):
Total pre-tax income	382	367	196
Net interest income (expense):
Net interest income	1,053	642	738
Total assets:
Aggregate assets	56,737	36,154
Operating segments | Other
Net revenues:
Net revenues	(50)	(8)	(82)
Pre-tax income/(loss):
Total pre-tax income	(191)	(246)	(192)
Total assets:
Aggregate assets	1,937	2,534
Intersegment eliminations
Net revenues:
Net revenues	$ (464)	$ (267)	$ (251)