Quarterly report [Sections 13 or 15(d)]

SECURITIES AND OTHER INVESTMENTS (Narrative) (Details)

v3.26.3
SECURITIES AND OTHER INVESTMENTS (Narrative) (Details)
 9 Months Ended 12 Months Ended
Sep. 30, 2026
USD ($)
security
Sep. 30, 2025
USD ($)
Dec. 31, 2025
USD ($)
security
Schedule Of Debt Investments [Line Items]      
Available for sale securities past due or non-accrual $ 0   $ 0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss 416,810,000   313,266,000
AFS securities in an unrealized loss, credit related impairment 0   0
Available for sale securities, allowance for credit losses 0   0
HTM securities past due or non accrual 0   0
Restricted equity securities consist of Federal Reserve Bank stock 141,200,000   141,200,000
Federal Home Loan Bank Stock 48,900,000   $ 49,000,000
HTM accrued interest receivable write-offs 0 $ 0  
AFS accrued interest receivable write-offs $ 0 $ 0  
Restricted equity securities as a percentage of outstanding borrowings, required by FHLB 4.75%   4.75%
Restricted equity securities as a percentage of outstanding borrowings, required by FRB 6.00%   6.00%
Restricted stock, value $ 190,100,000   $ 190,200,000
Held-to-Maturity Securities      
Schedule Of Debt Investments [Line Items]      
Accrued interest receivable $ 7,500,000   $ 9,900,000
Available-for-sale Securities      
Schedule Of Debt Investments [Line Items]      
Available for sale securities that had been in a continuous loss position for more than 12 months, Number of issues | security 700   703
Accrued interest receivable $ 13,600,000   $ 15,000,000
Mortgage-Backed Securities, Issued by Private Enterprises [Member]      
Schedule Of Debt Investments [Line Items]      
SSFA rating percentage 20.00%   20.00%