Accumulated Other Comprehensive Income (Loss) (AOCI) - Changes in AOCI by Component (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes		$ (12,730)			$ (12,730)
Net current period other comprehensive income (loss), net of taxes	$ 873	142	$ (2,941)	$ 2,539	1,015	$ (402)
Balance at the end of the period, net of taxes	(11,715)				(11,715)
Accumulated Other Comprehensive Income (Loss)
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(12,588)	(12,730)	(14,317)	(16,856)	(12,730)	(16,856)
Other comprehensive income (loss) before reclassification, net of taxes	891		(2,916)		1,051	(353)
Amounts reclassified from other comprehensive income (loss), net of taxes	(18)		(25)		(36)	(49)
Net current period other comprehensive income (loss), net of taxes	873	142	(2,941)	2,539	1,015	(402)
Balance at the end of the period, net of taxes	(11,715)	(12,588)	(17,258)	(14,317)	(11,715)	(17,258)
Unrealized Gains (Losses) on Available-for-Sale Securities and I/O Strips
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(6,853)	(7,029)	(8,817)	(11,394)	(7,029)	(11,394)
Other comprehensive income (loss) before reclassification, net of taxes	907		(2,902)		1,083	(325)
Net current period other comprehensive income (loss), net of taxes	907		(2,902)		1,083	(325)
Balance at the end of the period, net of taxes	(5,946)	(6,853)	(11,719)	(8,817)	(5,946)	(11,719)
Defined Benefit Pension Plan Items
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(5,735)	(5,701)	(5,500)	(5,462)	(5,701)	(5,462)
Other comprehensive income (loss) before reclassification, net of taxes	(16)		(14)		(32)	(28)
Amounts reclassified from other comprehensive income (loss), net of taxes	(18)		(25)		(36)	(49)
Net current period other comprehensive income (loss), net of taxes	(34)		(39)		(68)	(77)
Balance at the end of the period, net of taxes	$ (5,769)	$ (5,735)	$ (5,539)	$ (5,500)	$ (5,769)	$ (5,539)