| Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] |
| | | | | | | Quoted | | | | | | | | | |
| | | | | | | Prices in | | | | | | | | | |
| | | | | | | Active | | | | | | | | | |
| | | | | | | Markets | | | Significant | | | | | |
| | | | | | | for | | | Other | | | Significant | |
| | | | | | | Identical | | | Observable | | | Unobservable | |
| | | | | | | Assets | | | Inputs | | | Inputs | |
| (Dollars in thousands) | | Total | | | (Level 1) | | | (Level 2) | | | (Level 3) | |
| June 30, 2026 | | | | | | | | | | | | | | | | |
| Available for sale securities | | | | | | | | | | | | | | | | |
| U.S. Treasury notes and bonds | | $ | 55,099 | | | $ | 0 | | | $ | 55,099 | | | $ | 0 | |
| U.S. Government agency debt obligations | | | 687,508 | | | | 0 | | | | 687,508 | | | | 0 | |
| Mortgage-backed securities | | | 69,199 | | | | 0 | | | | 69,199 | | | | 0 | |
| Municipal general obligation bonds | | | 211,173 | | | | 0 | | | | 211,173 | | | | 0 | |
| Municipal revenue bonds | | | 63,628 | | | | 0 | | | | 63,628 | | | | 0 | |
| Other investments | | | 38,922 | | | | 0 | | | | 38,922 | | | | 0 | |
| Interest rate swaps | | | 16,923 | | | | 0 | | | | 16,923 | | | | 0 | |
| Total assets | | $ | 1,142,452 | | | $ | 0 | | | $ | 1,142,452 | | | $ | 0 | |
| | | | | | | | | | | | | | | | | |
| Interest rate swaps | | | 17,126 | | | | 0 | | | | 17,126 | | | | 0 | |
| Total liabilities | | $ | 17,126 | | | $ | 0 | | | $ | 17,126 | | | $ | 0 | |
| | | | | | | | | | | | | | | | | |
| December 31, 2025 | | | | | | | | | | | | | | | | |
| Available for sale securities | | | | | | | | | | | | | | | | |
| U.S. Treasury notes and bonds | | $ | 55,501 | | | $ | 0 | | | $ | 55,501 | | | $ | 0 | |
| U.S. Government agency debt obligations | | | 639,773 | | | | 0 | | | | 639,773 | | | | 0 | |
| Mortgage-backed securities | | | 75,762 | | | | 0 | | | | 75,762 | | | | 0 | |
| Municipal general obligation bonds | | | 215,063 | | | | 0 | | | | 215,063 | | | | 0 | |
| Municipal revenue bonds | | | 65,004 | | | | 0 | | | | 65,004 | | | | 0 | |
| Other investments | | | 51,127 | | | | 0 | | | | 51,127 | | | | 0 | |
| Interest rate swaps | | | 23,212 | | | | 0 | | | | 23,212 | | | | 0 | |
| Total assets | | $ | 1,125,442 | | | $ | 0 | | | $ | 1,125,442 | | | $ | 0 | |
| | | | | | | | | | | | | | | | | |
| Interest rate swaps | | | 23,532 | | | | 0 | | | | 23,532 | | | | 0 | |
| Total liabilities | | $ | 23,532 | | | $ | 0 | | | $ | 23,532 | | | $ | 0 | |
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