Investment Securities - Amount of Securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	$ 18,801	$ 130,888
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(67)	(13,908)
12 months or longer, fair value	240,054	135,922
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(35,562)	(28,537)
Total, fair value	258,855	266,810
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(35,629)	(42,445)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than twelve months, fair value	6,005	65,044
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, accumulated loss	(94)	(5,894)
Twelve months or longer, fair value	122,272	69,024
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(17,406)	(14,765)
Total, fair value	128,277	134,068
Held-to-maturity securities, unrealized loss position, accumulated loss	(17,500)	(20,659)
Residential Mortgage Backed Securities [Member]
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	16,992	128,831
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(65)	(13,843)
12 months or longer, fair value	238,053	133,902
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(35,362)	(28,300)
Total, fair value	255,045	262,733
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(35,427)	(42,143)
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position [Abstract]
Less than twelve months, fair value	6,005	65,044
Held-to-maturity securities, continuous unrealized loss position, less than 12 months, accumulated loss	(94)	(5,894)
Twelve months or longer, fair value	122,272	69,024
Held-to-maturity securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(17,406)	(14,765)
Total, fair value	128,277	134,068
Held-to-maturity securities, unrealized loss position, accumulated loss	(17,500)	(20,659)
State and Political Subdivisions [Member]
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	1,029	1,255
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(1)	(42)
12 months or longer, fair value	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Total, fair value	1,029	1,255
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(1)	(42)
Collateralized Mortgage Obligations [Member]
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	0	302
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	0	(22)
12 months or longer, fair value	2,001	2,020
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(200)	(237)
Total, fair value	2,001	2,322
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(200)	(259)
Corporate Bonds [Member]
Debt Securities, Available-for-sale, Unrealized Loss Position [Line Items]
Less than 12 months, fair value	780	500
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(1)	(1)
12 months or longer, fair value	0	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	0	0
Total, fair value	780	500
Available-for-sale securities, continuous unrealized loss position, accumulated loss	$ (1)	$ (1)