v3.26.1
BANK DEPOSITS, Bank Deposits by Insured and Uninsured (Details) - USD ($)
$ in Millions
Mar. 31, 2026
Sep. 30, 2025
Deposits [Abstract]    
FDIC-insured bank deposits $ 52,188 $ 49,117
Bank deposits exceeding FDIC insurance limit 10,235 9,780
Total bank deposits $ 62,423 $ 58,897
FDIC-insured bank deposits as a % of total bank deposits 84.00% 83.00%
Related Party Transaction [Line Items]    
Bank deposits exceeding FDIC insurance limit $ 10,235 $ 9,780
Related party    
Deposits [Abstract]    
Bank deposits exceeding FDIC insurance limit 1,500 1,240
Related Party Transaction [Line Items]    
Bank deposits exceeding FDIC insurance limit $ 1,500 $ 1,240