Accumulated Other Comprehensive Income (AOCI) - Changes in AOCI by Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	$ (16,856)
Net current period other comprehensive income (loss), net of taxes	4,126	$ (5,860)	$ (279)
Balance at the end of the period, net of taxes	(12,730)	(16,856)
Accumulated Other Comprehensive Loss
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(16,856)	(10,996)
Other comprehensive income (loss) before reclassification, net of taxes	4,224	(6,152)
Amounts reclassified from other comprehensive income (loss), net of taxes	(98)	292
Net current period other comprehensive income (loss), net of taxes	4,126	(5,860)	(279)
Balance at the end of the period, net of taxes	(12,730)	(16,856)	(10,996)
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	(11,394)	2,153
Other comprehensive income (loss) before reclassification, net of taxes	4,365	(13,547)
Net current period other comprehensive income (loss), net of taxes	4,365	(13,547)
Balance at the end of the period, net of taxes	(7,029)	(11,394)	2,153
Defined Benefit Pension Plan Items
Changes in AOCI by Component
Balance at the beginning of the period, net of taxes	(5,462)	(13,149)
Other comprehensive income (loss) before reclassification, net of taxes	(141)	7,395
Amounts reclassified from other comprehensive income (loss), net of taxes	(98)	292
Net current period other comprehensive income (loss), net of taxes	(239)	7,687
Balance at the end of the period, net of taxes	$ (5,701)	$ (5,462)	$ (13,149)