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, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Accumulated Other Comprehensive Loss [Line Items]
Unrealized holding loss on available-for-sale securities arising during the period, Pretax	$ (1,127)	$ (5,189)	$ (1,722)	$ (15,334)
Beginning balance, After-tax			(12,919)
Other comprehensive loss	(851)	(4,049)	(1,248)	(11,927)
Ending Balance, After-tax	(14,167)		(14,167)
Accumulated Net Unrealized Investment Gain (Loss) [Member]
Accumulated Other Comprehensive Loss [Line Items]
Beginning balance, Pretax	(16,856)	(12,663)	(16,354)	(2,691)
Unrealized holding loss on available-for-sale securities arising during the period, Pretax	(1,127)	(5,189)	(1,722)	(15,334)
Amortization of held-to-maturity discount resulting from transfer, Pretax	50	64	143	237
Total other comprehensive loss, Pretax	(1,077)	(5,125)	(1,579)	(15,097)
Ending balance, Pretax	(17,933)	(17,788)	(17,933)	(17,788)
Beginning balance, Tax Effect	3,540	2,660	3,435	566
Unrealized holding loss on available-for-sale securities arising during the period, Tax Effect	237	1,090	361	3,220
Amortization of held-to-maturity discount resulting from transfer, Tax Effect	(11)	(14)	(30)	(50)
Total other comprehensive loss, Tax Effect	226	1,076	331	3,170
Ending Balance, Tax Effect	3,766	3,736	3,766	3,736
Beginning balance, After-tax	(13,316)	(10,003)	(12,919)	(2,125)
Unrealized holding loss on available-for-sale securities arising during the period, After-Tax	(890)	(4,099)	(1,361)	(12,114)
Amortization of held-to-maturity discount resulting from transfer, After-tax	40	50	113	187
Other comprehensive loss	(851)	(4,049)	(1,248)	(11,927)
Ending Balance, After-tax	$ (14,167)	$ (14,052)	$ (14,167)	$ (14,052)