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Note 3 - Loans and Allowance for Credit Losses (Details Textual) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Financing Receivable, before Allowance for Credit Loss | $ 4,600,781 | $ 4,303,758 |
Financing Receivable, Nonaccrual, Interest Income | 300 | 200 | $ 100
Financing Receivable, Revolving, Converted to Term Loan During Period | 9,100 | 6,400 |
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) | 1,300 |  |
Financing Receivable, Allowance for Credit Loss, Period Increase (Decrease) From Forecast Changes | (2,200) | (2,000) |
Financing Receivable, Individually Evaluated for Credit Loss | 7,400 | 5,400 |
Financing Receivable, Allowance for Credit Losses, Individually Evaluated for Impairment | 2,200 | 400 |
Commercial Portfolio Segment [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | $ 3,707,304 | $ 3,415,299 |
Financing Receivables, Prepayment Speed Assumed | 2.00% | 2.00% |
Commercial Portfolio Segment [Member] | Commercial and Industrial, Credit Cards to Business Customers [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | $ 19,100 | $ 17,800 |
Retail Portfolio Segment [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | 893,477 | 888,459 |
Retail Portfolio Segment [Member] | Home Equity Loan [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | 52,000 | 38,100 |
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member] |  |  |
Financing Receivable, before Allowance for Credit Loss | $ 827,597 | $ 837,406 |
Financing Receivables, Prepayment Speed Assumed | 7.80% | 9.00% |

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