Other Comprehensive Income (Loss) - Components of Other Comprehensive Income Loss (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income (loss), before tax	$ 13,302	$ (84,791)	$ (7,339)
Other comprehensive loss, Tax Effect	2,787	(17,926)	(1,540)
Other comprehensive loss, Net of Tax	10,515	(66,865)	(5,799)
Net unrealized Losses on Investment Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income (loss) before reclassifications	12,330	(85,517)	(8,570)
Amounts reclassified from accumulated other comprehensive income (loss), Before Tax	0	(10)	(1)
Other comprehensive income (loss), before tax	12,330	(85,527)	(8,571)
Other comprehensive income (loss), before reclassifications	2,583	(18,079)	(1,799)
Amounts reclassified from accumulated other comprehensive income (loss), Tax Effect	0	(2)	0
Other comprehensive loss, Tax Effect	2,583	(18,081)	(1,799)
Other comprehensive income (loss) before reclassifications, Net of Tax	9,747	(67,438)	(6,771)
Amounts reclassified from accumulated other comprehensive income (loss), Net of Tax	0	(8)	(1)
Other comprehensive loss, Net of Tax	9,747	(67,446)	(6,772)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive income (loss) before reclassifications	972	736	992
Amounts reclassified from accumulated other comprehensive income (loss), Before Tax	0	0	240
Other comprehensive income (loss), before tax	972	736	1,232
Other comprehensive income (loss), before reclassifications	204	155	209
Amounts reclassified from accumulated other comprehensive income (loss), Tax Effect	0	0	50
Other comprehensive loss, Tax Effect	204	155	259
Other comprehensive income (loss) before reclassifications, Net of Tax	768	581	783
Amounts reclassified from accumulated other comprehensive income (loss), Net of Tax	0	0	190
Other comprehensive loss, Net of Tax	$ 768	$ 581	$ 973