| Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] |
The following table presents the changes in the components of AOCI for the three and six months ended June 30, 2026 and 2025 (in thousands). | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Net Unrealized Gains (Losses) on Available-for-Sale Securities (1) | | Net Unrealized Gains (Losses) on Cash Flow Hedges | | | | Postretirement Benefits | | Total AOCI | | Three Months Ended June 30, 2026 | | | | | | | | | | | Balance at April 1, 2026 | $ | 183,119 | | | $ | 21,488 | | | | | $ | 805 | | | $ | 205,412 | | | Reclassifications from AOCI to net income | | | | | | | | | | | | | | | | | | | | | Gains on cash flow hedges included in interest expense | — | | | (2,566) | | | | | — | | | (2,566) | | | | | | | | | | | | Amortization of prior service costs and net actuarial gains recognized in other income (loss) | — | | | — | | | | | (18) | | | (18) | | | Other amounts of other comprehensive income (loss) | | | | | | | | | | | Net unrealized gains on available-for-sale securities | 58,671 | | | — | | | | | — | | | 58,671 | | | Unrealized gains on cash flow hedges | — | | | 5,177 | | | | | — | | | 5,177 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Total other comprehensive income (loss) | 58,671 | | | 2,611 | | | | | (18) | | | 61,264 | | | Balance at June 30, 2026 | $ | 241,790 | | | $ | 24,099 | | | | | $ | 787 | | | $ | 266,676 | | | | | | | | | | | | | | | | | | | | | | | Three Months Ended June 30, 2025 | | | | | | | | | | | Balance at April 1, 2025 | $ | 125,425 | | | $ | 38,844 | | | | | $ | 849 | | | $ | 165,118 | | Reclassifications from AOCI to net income | | | | | | | | | | | | | | | | | | | | | Gains on cash flow hedges included in interest expense | — | | | (5,977) | | | | | — | | | (5,977) | | | | | | | | | | | | Amortization of prior service costs and net actuarial gains recognized in other income (loss) | — | | | — | | | | | (17) | | | (17) | | | Other amounts of other comprehensive income (loss) | | | | | | | | | | | Net unrealized losses on available-for-sale securities | (54,661) | | | — | | | | | — | | | (54,661) | | | Unrealized losses on cash flow hedges | — | | | (3,293) | | | | | — | | | (3,293) | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Total other comprehensive loss | (54,661) | | | (9,270) | | | | | (17) | | | (63,948) | | | Balance at June 30, 2025 | $ | 70,764 | | | $ | 29,574 | | | | | $ | 832 | | | $ | 101,170 | | _____________________________ (1) Net unrealized gains (losses) on available-for-sale securities are net of unrealized gains and losses relating to hedged interest rate risk included in net income. |
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Net Unrealized Gains (Losses) on Available-for-Sale Securities (1) | | Net Unrealized Gains (Losses) on Cash Flow Hedges | | | | Postretirement Benefits | | Total AOCI | | Six Months Ended June 30, 2026 | | | | | | | | | | | Balance at January 1, 2026 | $ | 183,147 | | | $ | 20,525 | | | | | $ | 796 | | | $ | 204,468 | | Reclassifications from AOCI to net income | | | | | | | | | | | | | | | | | | | | | Gains on cash flow hedges included in interest expense | — | | | (5,961) | | | | | — | | | (5,961) | | | | | | | | | | | | Amortization of prior service costs and net actuarial gains recognized in other income (loss) | — | | | — | | | | | (45) | | | (45) | | | Other amounts of other comprehensive income (loss) | | | | | | | | | | | Net unrealized gains on available-for-sale securities | 58,643 | | | — | | | | | — | | | 58,643 | | | Unrealized gains on cash flow hedges | — | | | 9,535 | | | | | — | | | 9,535 | | | | | | | | | | | | | Actuarial gain | — | | | — | | | | | 36 | | | 36 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Total other comprehensive income (loss) | 58,643 | | | 3,574 | | | | | (9) | | | 62,208 | | | Balance at June 30, 2026 | $ | 241,790 | | | $ | 24,099 | | | | | $ | 787 | | | $ | 266,676 | | | | | | | | | | | | | Six Months Ended June 30, 2025 | | | | | | | | | | | Balance at January 1, 2025 | $ | 125,305 | | | $ | 52,322 | | | | | $ | 1,043 | | | $ | 178,670 | | Reclassifications from AOCI to net income | | | | | | | | | | | | | | | | | | | | | Gains on cash flow hedges included in interest expense | — | | | (11,709) | | | | | — | | | (11,709) | | | | | | | | | | | | Amortization of prior service costs and net actuarial gains recognized in other income (loss) | — | | | — | | | | | (64) | | | (64) | | Other amounts of other comprehensive income (loss) | | | | | | | | | | | Net unrealized losses on available-for-sale securities | (54,541) | | | — | | | | | — | | | (54,541) | | | Unrealized losses on cash flow hedges | — | | | (11,039) | | | | | — | | | (11,039) | | | | | | | | | | | | | | | | | | | | | | | Actuarial loss | — | | | — | | | | | (147) | | | (147) | | | Total other comprehensive loss | (54,541) | | | (22,748) | | | | | (211) | | | (77,500) | | | Balance at June 30, 2025 | $ | 70,764 | | | $ | 29,574 | | | | | $ | 832 | | | $ | 101,170 | | _____________________________ (1) Net unrealized gains (losses) on available-for-sale securities are net of unrealized gains and losses relating to hedged interest rate risk included in net income. |
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