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, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Net Unrealized Holding Gain (Loss) on Securities Available for Sale, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance	$ (15,429)		$ (21,713)	$ (24,635)		$ (23,899)	$ (21,713)	$ (23,899)
Other comprehensive income - before reclassifications	1,673			7,816			7,957	7,080
Amount reclassified from accumulated other comprehensive income (loss)	0			0			0	0
Other comprehensive income, net of tax	1,673			7,816			7,957	7,080
Balance	(13,756)	$ (15,429)		(16,819)	$ (24,635)		(13,756)	(16,819)
Net Change in Overfunded Position in Pension and Postretirement Plans Arising During the Year, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance	21,266		21,266	13,476		13,476	21,266	13,476
Other comprehensive income - before reclassifications	0			0			0	0
Amount reclassified from accumulated other comprehensive income (loss)	0			0			0	0
Other comprehensive income, net of tax	0			0			0	0
Balance	21,266	21,266		13,476	13,476		21,266	13,476
Net Change in Net Actuarial Gain and Prior Service Cost on Pension and Postretirement Benefit Plans, Net of Tax [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance	(4,174)		(3,414)	(3,109)		(2,814)	(3,414)	(2,814)
Other comprehensive income - before reclassifications	0			0			0	0
Amount reclassified from accumulated other comprehensive income (loss)	(381)			(148)			(1,141)	(443)
Other comprehensive income, net of tax	(381)			(148)			(1,141)	(443)
Balance	(4,555)	(4,174)		(3,257)	(3,109)		(4,555)	(3,257)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss) [Abstract]
Balance	1,663	(132)	(3,861)	(14,268)	(14,763)	(13,237)	(3,861)	(13,237)
Other comprehensive income - before reclassifications	1,673			7,816			7,957	7,080
Amount reclassified from accumulated other comprehensive income (loss)	(381)			(148)			(1,141)	(443)
Other comprehensive income, net of tax	1,292	1,795	3,729	7,668	495	(1,526)	6,816	6,637
Balance	$ 2,955	$ 1,663	$ (132)	$ (6,600)	$ (14,268)	$ (14,763)	$ 2,955	$ (6,600)