| 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) | |
| September 30, 2026 | | | | | | | | | | | | | | | | |
| Available for sale securities | | | | | | | | | | | | | | | | |
| U.S. Treasury notes and bonds | | $ | 50,414 | | | $ | 0 | | | $ | 50,414 | | | $ | 0 | |
| U.S. Government agency debt obligations | | | 682,002 | | | | 0 | | | | 682,002 | | | | 0 | |
| Mortgage-backed securities | | | 68,712 | | | | 0 | | | | 68,712 | | | | 0 | |
| Municipal general obligation bonds | | | 199,010 | | | | 0 | | | | 199,010 | | | | 0 | |
| Municipal revenue bonds | | | 61,647 | | | | 0 | | | | 61,647 | | | | 0 | |
| Other investments | | | 36,231 | | | | 0 | | | | 36,231 | | | | 0 | |
| Interest rate swaps | | | 28,478 | | | | 0 | | | | 28,478 | | | | 0 | |
| Total assets | | $ | 1,126,494 | | | $ | 0 | | | $ | 1,126,494 | | | $ | 0 | |
| | | | | | | | | | | | | | | | | |
| Interest rate swaps | | | 28,559 | | | | 0 | | | | 28,559 | | | | 0 | |
| Total liabilities | | $ | 28,559 | | | $ | 0 | | | $ | 28,559 | | | $ | 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 | |
|
| Fair Value, Assets and Liabilities Measured on Nonrecurring Basis, Valuation Techniques [Table Text Block] |
| | | | | | | Quoted | | | | | | | | | |
| | | | | | | Prices in | | | | | | | | | |
| | | | | | | Active | | | Significant | | | | | |
| | | | | | | Markets for | | | Other | | | Significant | |
| | | | | | | Identical | | | Observable | | | Unobservable | |
| | | | | | | Assets | | | Inputs | | | Inputs | |
| (Dollars in thousands) | | Total | | | (Level 1) | | | (Level 2) | | | (Level 3) | |
| September 30, 2026 | | | | | | | | | | | | | | | | |
| Collateral dependent loans | | $ | 1,623 | | | $ | 0 | | | $ | 0 | | | $ | 1,623 | |
| | | | | | | | | | | | | | | | | |
| December 31, 2025 | | | | | | | | | | | | | | | | |
| Collateral dependent loans | | $ | 991 | | | $ | 0 | | | $ | 0 | | | $ | 991 | |
|