| Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] |
| | | | | | Reclassification | | | | | | | | | |
| | Net unrealized | | | adjustment for | | | | | | | | | |
| | holding (losses) | | | (gains) losses | | | | | | | | | |
| | gains on available | | | realized in income | | | Change in funded status | | | | | |
(In Thousands of Dollars) | | for sale securities | | | on fair value hedge | | | of post-retirement plan | | | Total | |
Balance December 31, 2025 | | $ | (143,597 | ) | | $ | (476 | ) | | $ | (2 | ) | | $ | (144,075 | ) |
Other comprehensive (loss) before reclassification | | | (6,270 | ) | | | 0 | | | | 0 | | | | (6,270 | ) |
Amounts reclassified from accumulated other comprehensive income | | | 0 | | | | 190 | | | | 0 | | | | 190 | |
Net current period other comprehensive (loss) income | | | (6,270 | ) | | | 190 | | | | 0 | | | | (6,080 | ) |
Balance March 31, 2026 | | $ | (149,867 | ) | | $ | (286 | ) | | $ | (2 | ) | | $ | (150,155 | ) |
Other comprehensive income before reclassification | | | 3,264 | | | | 0 | | | | 0 | | | | 3,264 | |
Amounts reclassified from accumulated other comprehensive income | | | 0 | | | | 202 | | | | 0 | | | | 202 | |
Net current period other comprehensive income | | | 3,264 | | | | 202 | | | | 0 | | | | 3,466 | |
Balance June 30, 2026 | | $ | (146,603 | ) | | $ | (84 | ) | | $ | (2 | ) | | $ | (146,689 | ) |
Other comprehensive (loss) before reclassification | | | (80,246 | ) | | | 0 | | | | 0 | | | | (80,246 | ) |
Amounts reclassified from accumulated other comprehensive income | | | 8,130 | | | | 85 | | | | 0 | | | | 8,215 | |
Net current period other comprehensive (loss) income | | | (72,116 | ) | | | 85 | | | | 0 | | | | (72,031 | ) |
Balance September 30, 2026 | | $ | (218,719 | ) | | $ | 1 | | | $ | (2 | ) | | $ | (218,720 | ) |
| | | | | | | | | | | | | | | | |
Balance December 31, 2024 | | $ | (192,860 | ) | | $ | (403 | ) | | $ | (2 | ) | | $ | (193,265 | ) |
Other comprehensive income (loss) before reclassification | | | 15,096 | | | | 0 | | | | 0 | | | | 15,096 | |
Amounts reclassified from accumulated other comprehensive income (loss) | | | 1,054 | | | | (186 | ) | | | 0 | | | | 868 | |
Net current period other comprehensive income (loss) | | | 16,150 | | | | (186 | ) | | | 0 | | | | 15,964 | |
Balance March 31, 2025 | | $ | (176,710 | ) | | $ | (589 | ) | | $ | (2 | ) | | $ | (177,301 | ) |
Other comprehensive income (loss) before reclassification | | | 517 | | | | 0 | | | | 0 | | | | 517 | |
Amounts reclassified from accumulated other comprehensive income (loss) | | | 0 | | | | 46 | | | | 0 | | | | 46 | |
Net current period other comprehensive income (loss) | | | 517 | | | | 46 | | | | 0 | | | | 563 | |
Balance June 30, 2025 | | $ | (176,193 | ) | | $ | (543 | ) | | $ | (2 | ) | | $ | (176,738 | ) |
Other comprehensive income (loss) before reclassification | | | 20,882 | | | | 0 | | | | 0 | | | | 20,882 | |
Amounts reclassified from accumulated other comprehensive income (loss) | | | 758 | | | | 13 | | | | 0 | | | | 771 | |
Net current period other comprehensive income (loss) | | | 21,640 | | | | 13 | | | | 0 | | | | 21,653 | |
Balance September 30, 2025 | | $ | (154,553 | ) | | $ | (530 | ) | | $ | (2 | ) | | $ | (155,085 | ) |
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