v3.26.1
SECURITIES - Narrative (Details)
9 Months Ended
Jun. 30, 2026
USD ($)
security
Jun. 30, 2025
USD ($)
Sep. 30, 2025
USD ($)
Debt Securities, Available-for-sale [Line Items]      
AFS number of securities in an unrealized loss position (in securities) | security 146    
Federal reserve bank stock $ 19,700,000   $ 19,700,000
Federal home loan bank stock 11,200,000   5,000,000.0
Impairment recognized 200,000 $ 0  
Marketable      
Debt Securities, Available-for-sale [Line Items]      
Equity securities 4,800,000   3,800,000
Unrealized gain (loss) 0 (100,000)  
Non-marketable      
Debt Securities, Available-for-sale [Line Items]      
Equity securities 13,500,000   13,200,000
Unrealized gain (loss) 1,700,000 1,100,000  
Equity securities without readily determinable fair value, amount $ 14,900,000   $ 12,000,000.0
Number of equity securities sold | security 0    
Non-marketable | Visa      
Debt Securities, Available-for-sale [Line Items]      
Equity securities   0  
Realized gain on equity securities   $ 400,000