v3.26.1
INVESTMENT SECURITIES - Additional Information (Details) - USD ($)
$ in Thousands
6 Months Ended
Aug. 03, 2026
Jun. 30, 2026
Dec. 31, 2025
Investment Securities Pledged as Collateral      
Accrued interest and fees receivable   $ 6,100  
Accrued interest receivable on available-for-sale debt securities   11,300  
Investment securities pledged to collateralize certain deposits and borrowings   2,150,000 $ 2,060,000
Fair Value   $ 2,957,963 2,875,341
Percentage of first half of subscription on FRB stock   50.00%  
Percentage of remaining half of subscription on FRB stock   50.00%  
Asset Pledged as Collateral with Right [Member]      
Investment Securities Pledged as Collateral      
Fair Value   $ 318,329 319,478
Government securities      
Investment Securities Pledged as Collateral      
Fair Value   2,219,381 2,195,226
Government securities | Securities Sold under Agreements to Repurchase      
Investment Securities Pledged as Collateral      
Investment securities pledged to collateralize certain deposits and borrowings   318,300 319,500
Obligations of state and political subdivisions      
Investment Securities Pledged as Collateral      
Fair Value   $ 435,993 $ 391,917
Subsequent Event | Government securities      
Investment Securities Pledged as Collateral      
Proceeds from Sale of Debt Securities, Available-for-Sale $ 296,800    
Debt Securities, Available-for-Sale, Gain (Loss) $ 3,000