Accumulated Other Comprehensive Loss - Schedule of Changes in Accumulated Other Comprehensive Loss by Component Net of Tax (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Accumulated Other Comprehensive Loss [Line Items]
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Pretax	$ 3,409	$ (1,127)	$ 3,556	$ (1,722)
Beginning balance, After-tax			(10,270)
Other comprehensive income (loss)	2,731	(851)	2,916	(1,248)
Ending Balance, After-tax	(7,354)		(7,354)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance, Pretax	(12,765)	(16,856)	(12,999)	(16,354)
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Pretax	3,409	(1,127)	3,556	(1,722)
Amortization of held-to-maturity discount resulting from transfer, Pretax	48	50	135	143
Total other comprehensive income (loss), Pretax	3,457	(1,077)	3,691	(1,579)
Ending balance, Pretax	(9,308)	(17,933)	(9,308)	(17,933)
Beginning balance, Tax Effect	2,680	3,540	2,729	3,435
Unrealized holding gain (loss) on available-for-sale securities arising during the period, Tax Effect	(716)	237	(747)	361
Amortization of held-to-maturity discount resulting from transfer, Tax Effect	(10)	(11)	(28)	(30)
Total other comprehensive income (loss), Tax Effect	(726)	226	(775)	331
Ending Balance, Tax Effect	1,954	3,766	1,954	3,766
Beginning balance, After-tax	(10,085)	(13,316)	(10,270)	(12,919)
Unrealized holding gain (loss) on available-for-sale securities arising during the period, After-Tax	2,693	(890)	2,809	(1,361)
Amortization of held-to-maturity discount resulting from transfer, After-tax	38	39	107	113
Other comprehensive income (loss)	2,731	(851)	2,916	(1,248)
Ending Balance, After-tax	$ (7,354)	$ (14,167)	$ (7,354)	$ (14,167)