SEGMENT INFORMATION, Classified by Major Geographic Areas (Details) £ in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 GBP (£)	Jun. 01, 2022 USD ($)	Jan. 21, 2022 USD ($)	Sep. 30, 2021 USD ($)
Revenues:
Total net revenues	$ 2,718	$ 2,471	$ 8,172	$ 7,065
Pre-tax income
Total pre-tax income	415	385	1,406	1,231
Total assets:
Total assets	86,111		86,111					$ 61,891
Goodwill:
Goodwill	1,335		1,335					660
TriState Capital
Goodwill:
Goodwill	529		529			$ 529
Charles Stanley
Goodwill:
Goodwill	147		147		£ 121		$ 164
U.S.
Revenues:
Total net revenues	2,472	2,275	7,491	6,548
Pre-tax income
Total pre-tax income	393	353	1,330	1,165
Total assets:
Total assets	78,911		78,911					57,952
Goodwill:
Goodwill	1,148		1,148					619
Canada
Revenues:
Total net revenues	138	128	404	363
Pre-tax income
Total pre-tax income	20	15	52	41
Total assets:
Total assets	4,153		4,153					3,724
Goodwill:
Goodwill	25		25					25
Europe
Revenues:
Total net revenues	108	68	277	154
Pre-tax income
Total pre-tax income	2	$ 17	24	$ 25
Total assets:
Total assets	3,047		3,047					215
Goodwill:
Goodwill	$ 162		$ 162					$ 16