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Accumulated Other Comprehensive Income - Unrealized gains (losses) (Details) - USD ($) $ in Thousands	3 Months Ended
	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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Accumulated Other Comprehensive Income (Loss) [Roll Forward]

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Amount, after tax, of accumulated increase (decrease) in equity from transaction and other event and circumstance from nonowner source.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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