BANK DEPOSITS, Bank Deposits by Insured and Uninsured (Details) - USD ($) $ in Millions	Sep. 30, 2025	Sep. 30, 2024
Deposits [Abstract]
FDIC-insured bank deposits	$ 49,117	$ 48,964
Bank deposits exceeding FDIC insurance limit	9,780	7,046
Total bank deposits	$ 58,897	$ 56,010
FDIC-insured bank deposits as a % of total bank deposits	83.00%	87.00%
Related Party Transaction [Line Items]
Bank deposits exceeding FDIC insurance limit	$ 9,780	$ 7,046
Related party
Deposits [Abstract]
Bank deposits exceeding FDIC insurance limit	1,240	1,050
Related Party Transaction [Line Items]
Bank deposits exceeding FDIC insurance limit	$ 1,240	$ 1,050