| Comprehensive Income (Loss) Note [Text Block] |
Note 12- Change in Accumulated Other Comprehensive Income ("AOCI")
Our AOCI includes unrealized gains (losses) on available-for-sale securities, defined benefit plan assets and derivatives as well as an unrecognized defined benefit plan prior service cost. The following table presents changes to accumulated other comprehensive income after-tax for the periods shown:
| (dollars in thousands) | | Unrealized Gains and Losses on Available-for-Sale Securities | | | Net Actuarial Gains (Losses) on DB Plan Assets | | | Unrecognized DB Plan Prior Service Cost, Net of Amortization | | | Unrealized (Losses) Gains on Fair Value of Hedged Items | | | Total | |
| Balance at June 30, 2026 | | $ | (20,486 | ) | | $ | (387 | ) | | $ | (1,125 | ) | | $ | (179 | ) | | $ | (22,177 | ) |
| Other comprehensive loss before reclassification | | | (9,348 | ) | | | — | | | | — | | | | — | | | | (9,348 | ) |
| Amounts reclassified from accumulated other comprehensive income | | | — | | | | — | | | | 29 | | | | 331 | | | | 360 | |
| Net other comprehensive (loss) income | | | (9,348 | ) | | | — | | | | 29 | | | | 331 | | | | (8,988 | ) |
| Balance at September 30, 2026 | | $ | (29,834 | ) | | $ | (387 | ) | | $ | (1,096 | ) | | $ | 152 | | | $ | (31,165 | ) |
| (dollars in thousands) | | Unrealized Gains and Losses on Available-for-Sale Securities | | | Net Actuarial Gains (Losses) on DB Plan Assets | | | Unrecognized DB Plan Prior Service Cost, Net of Amortization | | | Unrealized Losses on Fair Value of Hedged Items | | | Total | |
| Balance at June 30, 2025 | | $ | (25,674 | ) | | $ | (486 | ) | | $ | (1,244 | ) | | $ | (794 | ) | | $ | (28,198 | ) |
| Other comprehensive income before reclassification | | | 3,733 | | | | — | | | | — | | | | — | | | | 3,733 | |
| Amounts reclassified from accumulated other comprehensive income | | | — | | | | — | | | | 30 | | | | 6 | | | | 36 | |
| Net other comprehensive income | | | 3,733 | | | | — | | | | 30 | | | | 6 | | | | 3,769 | |
| Balance at September 30, 2025 | | $ | (21,941 | ) | | $ | (486 | ) | | $ | (1,214 | ) | | $ | (788 | ) | | $ | (24,429 | ) |
| (dollars in thousands) | | Unrealized Gains and Losses on Available-for-Sale Securities | | | Net Actuarial Gains (Losses) on DB Plan Assets | | | Unrecognized DB Plan Prior Service Cost, Net of Amortization | | | Unrealized (Losses) Gains on Fair Value of Hedged Items | | | Total | |
| Balance at December 31, 2025 | | $ | (20,058 | ) | | $ | (387 | ) | | $ | (1,184 | ) | | $ | (769 | ) | | $ | (22,398 | ) |
| Other comprehensive loss before reclassification | | | (9,776 | ) | | | — | | | | — | | | | — | | | | (9,776 | ) |
| Amounts reclassified from accumulated other comprehensive income | | | — | | | | — | | | | 88 | | | | 921 | | | | 1,009 | |
| Net other comprehensive (loss) income | | | (9,776 | ) | | | — | | | | 88 | | | | 921 | | | | (8,767 | ) |
| Balance at September 30, 2026 | | $ | (29,834 | ) | | $ | (387 | ) | | $ | (1,096 | ) | | $ | 152 | | | $ | (31,165 | ) |
| (dollars in thousands) | | Unrealized Gains and Losses on Available-for-Sale Securities | | | Net Actuarial Gains (Losses) on DB Plan Assets | | | Unrecognized DB Plan Prior Service Cost, Net of Amortization | | | Unrealized Losses on Fair Value of Hedged Items | | | Total | |
| Balance at December 31, 2024 | | $ | (28,210 | ) | | $ | (486 | ) | | $ | (1,303 | ) | | $ | (173 | ) | | $ | (30,172 | ) |
| Other comprehensive income before reclassification | | | 6,269 | | | | — | | | | — | | | | — | | | | 6,269 | |
| Amounts reclassified from accumulated other comprehensive income | | | — | | | | — | | | | 89 | | | | (615 | ) | | | (526 | ) |
| Net other comprehensive income (loss) | | | 6,269 | | | | — | | | | 89 | | | | (615 | ) | | | 5,743 | |
| Balance at September 30, 2025 | | $ | (21,941 | ) | | $ | (486 | ) | | $ | (1,214 | ) | | $ | (788 | ) | | $ | (24,429 | ) |
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