GOODWILL AND IDENTIFIABLE INTANGIBLE ASSETS, NET, Net Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 30, 2024	Sep. 30, 2023
Finite-lived Intangible Assets [Roll Forward]
Net identifiable intangible assets as of beginning of year	$ 470	$ 509
Amortization expense	(44)	(45)
Foreign currency translations	9	6
Net identifiable intangible assets as of end of year	435	470
Private Client Group
Finite-lived Intangible Assets [Roll Forward]
Net identifiable intangible assets as of beginning of year	168	178
Amortization expense	(15)	(16)
Foreign currency translations	9	6
Net identifiable intangible assets as of end of year	162	168
Capital Markets
Finite-lived Intangible Assets [Roll Forward]
Net identifiable intangible assets as of beginning of year	50	60
Amortization expense	(10)	(10)
Foreign currency translations	0	0
Net identifiable intangible assets as of end of year	40	50
Asset Management
Finite-lived Intangible Assets [Roll Forward]
Net identifiable intangible assets as of beginning of year	132	139
Amortization expense	(7)	(7)
Foreign currency translations	0	0
Net identifiable intangible assets as of end of year	125	132
Bank
Finite-lived Intangible Assets [Roll Forward]
Net identifiable intangible assets as of beginning of year	120	132
Amortization expense	(12)	(12)
Foreign currency translations	0	0
Net identifiable intangible assets as of end of year	$ 108	$ 120