Accumulated Other Comprehensive Income (Loss), Accumulated Other Comprehensive Income (Loss) Balances, Net of Tax (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	$ 621,389	$ 614,703	$ 599,987	$ 594,632	$ 592,895	$ 601,128	$ 599,987	$ 601,128
Other comprehensive loss - before reclassifications	(5,212)			(15,522)			(4,066)	(36,602)
Amount reclassified from accumulated other comprehensive income	(82)			(265)			(246)	(754)
Other comprehensive loss, net of tax	(5,294)	(2,837)	3,819	(15,787)	(7,053)	(14,516)	(4,312)	(37,356)
Balance	623,926	621,389	614,703	589,006	594,632	592,895	623,926	589,006
Accumulated Other Comprehensive Loss [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(26,212)	(23,375)	(27,194)	(9,422)	(2,369)	12,147	(27,194)	12,147
Other comprehensive loss, net of tax	(5,294)	(2,837)	3,819	(15,787)	(7,053)	(14,516)
Balance	(31,506)	(26,212)	(23,375)	(25,209)	(9,422)	(2,369)	(31,506)	(25,209)
Net Unrealized Holding Gain (Loss) on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(31,125)		(32,271)	(21,106)		(26)	(32,271)	(26)
Other comprehensive loss - before reclassifications	(5,212)			(15,522)			(4,066)	(36,602)
Amount reclassified from accumulated other comprehensive income	0			0			0	0
Other comprehensive loss, net of tax	(5,212)			(15,522)			(4,066)	(36,602)
Balance	(36,337)	(31,125)		(36,628)	(21,106)		(36,337)	(36,628)
Net Change in Overfunded Position in Pension and Postretirement Plans Arising During the Year, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	7,588		7,588	13,706		13,706	7,588	13,706
Other comprehensive loss - before reclassifications	0			0			0	0
Amount reclassified from accumulated other comprehensive income	0			0			0	0
Other comprehensive loss, net of tax	0			0			0	0
Balance	7,588	7,588		13,706	13,706		7,588	13,706
Net Change in Net Actuarial Gain and Prior Service Cost Credit on Pension and Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Balance	(2,675)		$ (2,511)	(2,022)		$ (1,533)	(2,511)	(1,533)
Other comprehensive loss - before reclassifications	0			0			0	0
Amount reclassified from accumulated other comprehensive income	(82)			(265)			(246)	(754)
Other comprehensive loss, net of tax	(82)			(265)			(246)	(754)
Balance	$ (2,757)	$ (2,675)		$ (2,287)	$ (2,022)		$ (2,757)	$ (2,287)