Accumulated Other Comprehensive Income - Amount reclassified from accumulated other comprehensive income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains, net				$ 5
Income tax expense	$ (3,027)	$ (4,639)	$ (10,143)	(14,172)
Net Income (Loss)	16,285	18,051	48,252	54,588
Amount reclassified from accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Net Income (Loss)	(146)	(315)	(440)	(940)
Unrealized gains and (Losses) on available- for-sale Securities | Amount reclassified from accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Securities gains, net				5
Income tax expense				(1)
Net Income (Loss)				4
Retirement plans | Amount reclassified from accumulated other comprehensive income
Reclassification Adjustment out of Accumulated Other Comprehensive Income on Derivatives [Line Items]
Change in funded status of post retirement benefits, net of taxes	(195)	(420)	(587)	(1,260)
Income tax expense	49	105	147	316
Net Income (Loss)	$ (146)	$ (315)	$ (440)	$ (944)