v3.26.1
FAIR VALUE DISCLOSURES - Estimated Fair Values of Financial Instruments (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Mar. 31, 2026
Sep. 30, 2025
Dec. 31, 2025
Financial assets      
Investment securities held-to-maturity $ 49,631   $ 58,545
Other Investments 137,018   129,564
Interest Receivable 57,590   54,100
Deposits      
Noninterest-bearing 3,982,753   3,465,470
Savings 6,460,546   5,973,532
Time 3,817,268   3,622,227
Federal Home Loan Bank Stock and Federal Reserve Bank Stock $ 124,400   116,700
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Discount Rate 11.69% 11.66%  
Servicing Assets and Servicing Liabilities at Fair Value, Assumptions Used to Estimate Fair Value, Prepayment Speed 6.75% 6.49%  
Impaired Commercial And Commercial Real Estate Loans Member      
Deposits      
Principal Amount of Commercial and Commercial Real Estate Loans $ 34,200   38,100
Allowance for Loan and Lease Losses, Real Estate 12,900   16,100
Carrying value      
Financial assets      
Cash and interest-bearing deposits with other banks 1,202,900   775,891
Investment securities held-to-maturity 49,631   58,545
Other Investments 12,661   12,898
Loans and leases 13,311,125   13,237,583
Interest Receivable 79,692   71,940
Deposits      
Deposits 17,918,722   16,421,842
Short-term borrowings 620,457   675,332
Long-term debt 380,176   514,052
Interest Payable 39,216   38,304
Fair value      
Financial assets      
Cash and interest-bearing deposits with other banks 1,202,900   775,891
Investment securities held-to-maturity 45,373   54,334
Other Investments 12,661   12,898
Loans and leases 13,183,121   13,061,341
Interest Receivable 79,692   71,940
Deposits      
Deposits 17,909,049   16,415,852
Short-term borrowings 620,457   675,332
Long-term debt 330,944   473,291
Interest Payable 39,216   38,304
Fair Value, Inputs, Level 1 [Member] | Fair value      
Financial assets      
Cash and interest-bearing deposits with other banks 1,202,900   775,891
Investment securities held-to-maturity 0   0
Other Investments 1,613   1,850
Loans and leases 0   0
Interest Receivable 0   0
Deposits      
Deposits 0   0
Short-term borrowings 620,457   675,332
Long-term debt 0   0
Interest Payable 2,646   2,918
Fair Value, Inputs, Level 2 [Member] | Fair value      
Financial assets      
Cash and interest-bearing deposits with other banks 0   0
Investment securities held-to-maturity 45,373   54,334
Other Investments 40   40
Loans and leases 0   0
Interest Receivable 22,102   17,833
Deposits      
Deposits 17,909,049   16,415,852
Short-term borrowings 0   0
Long-term debt 330,944   473,291
Interest Payable 36,570   35,386
Fair Value, Inputs, Level 3 [Member] | Fair value      
Financial assets      
Cash and interest-bearing deposits with other banks 0   0
Investment securities held-to-maturity 0   0
Other Investments 11,008   11,008
Loans and leases 13,183,121   13,061,341
Interest Receivable     54,107
Deposits      
Deposits 0   0
Short-term borrowings 0   0
Long-term debt 0   0
Interest Payable $ 0   $ 0