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Accumulated Other Comprehensive Income - Unrealized gains (losses) (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2024 | Mar. 31, 2023
Accumulated Other Comprehensive Income (Loss) |  |
Beginning balance | $ (127,087) | $ (139,974)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | (11,023) | 14,385
Ending balance | (138,110) | (125,589)
Unrealized gains and (Losses) on available- for-sale Securities |  |
Accumulated Other Comprehensive Income (Loss) |  |
Beginning balance | (118,000) | (128,896)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | (11,096) | 14,238
Ending balance | (129,096) | (114,658)
Unrealized gains (losses) on securities available-for-sale without other than temporary impairment |  |
Accumulated Other Comprehensive Income (Loss) |  |
Beginning balance | (120,252) | (131,135)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | (11,010) | 14,291
Ending balance | (131,262) | (116,844)
Unrealized gains (losses) on securities available-for-sale with other than temporary impairment |  |
Accumulated Other Comprehensive Income (Loss) |  |
Beginning balance | 2,252 | 2,239
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | (86) | (53)
Ending balance | 2,166 | 2,186
Retirement plans |  |
Accumulated Other Comprehensive Income (Loss) |  |
Beginning balance | (9,087) | (11,078)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent | 73 | 147
Ending balance | $ (9,014) | $ (10,931)

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