GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS, NET, Schedule of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Goodwill [Roll Forward]
Goodwill as of beginning of year	$ 1,422	$ 660
Additions	0	795
Foreign currency translations	15	(33)
Goodwill as of end of year	1,437	1,422
Private Client Group
Goodwill [Roll Forward]
Goodwill as of beginning of year	550	417
Additions	0	164
Foreign currency translations	14	(31)
Goodwill as of end of year	564	550
Capital Markets
Goodwill [Roll Forward]
Goodwill as of beginning of year	274	174
Additions	0	102
Foreign currency translations	1	(2)
Goodwill as of end of year	275	274
Asset Management
Goodwill [Roll Forward]
Goodwill as of beginning of year	69	69
Additions	0	0
Foreign currency translations	0	0
Goodwill as of end of year	69	69
Bank
Goodwill [Roll Forward]
Goodwill as of beginning of year	529	0
Additions	0	529
Foreign currency translations	0	0
Goodwill as of end of year	$ 529	$ 529