Accumulated Other Comprehensive Income - Unrealized gains (losses) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Accumulated Other Comprehensive Income (Loss)
Balance	$ 571,945	$ 520,766	$ 549,041	$ 527,976
Balance	587,668	530,670	587,668	530,670
Unrealized gains and (Losses) on available- for-sale Securities
Accumulated Other Comprehensive Income (Loss)
Balance	(116,707)	(129,096)	(127,807)	(118,000)
Current period Change	2,946	3,535	14,046	(7,561)
Balance	(113,761)	(125,561)	(113,761)	(125,561)
Unrealized gains (losses) on securities available-for-sale without other than temporary impairment
Accumulated Other Comprehensive Income (Loss)
Balance	(118,883)	(131,262)	(129,979)	(120,252)
Current period Change	2,941	3,532	14,037	(7,478)
Balance	(115,942)	(127,730)	(115,942)	(127,730)
Unrealized gains (losses) on securities available-for-sale with other than temporary impairment
Accumulated Other Comprehensive Income (Loss)
Balance	2,176	2,166	2,172	2,252
Current period Change	5	3	9	(83)
Balance	2,181	2,169	2,181	2,169
Retirement plans
Accumulated Other Comprehensive Income (Loss)
Balance	(4,475)	(9,014)	(4,478)	(9,087)
Current period Change	2	74	5	147
Balance	(4,473)	(8,940)	(4,473)	(8,940)
Accumulated Other Comprehensive Income/(Loss)
Accumulated Other Comprehensive Income (Loss)
Balance	(121,182)	(138,110)	(132,285)	(127,087)
Current period Change	2,948	3,609	14,051	(7,414)
Balance	$ (118,234)	$ (134,501)	$ (118,234)	$ (134,501)