Investment Securities - Amount of Securities in Unrealized Loss Position (Detail) - USD ($) $ in Thousands	Mar. 31, 2024	Dec. 31, 2023
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than twelve months, fair value	$ 7,006	$ 6,005
Debt securities, held-to-maturity, continuous unrealized loss position, less than 12 months, accumulated loss	(170)	(94)
Twelve months or longer, fair value	117,016	122,272
Debt securities, held-to-maturity, continuous unrealized loss position, 12 months or longer, accumulated loss	(19,282)	(17,406)
Total, fair value	124,022	128,277
Debt securities, held-to-maturity, unrealized loss position, accumulated loss	(19,452)	(17,500)
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Less than twelve months, fair value	10,014	18,801
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(38)	(67)
Twelve months or longer, fair value	251,809	240,054
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(39,360)	(35,562)
Total, fair value	261,823	258,855
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(39,398)	(35,629)
Residential mortgage-backed securities
Debt Securities, Held-to-maturity, Continuous Unrealized Loss Position, Fair Value [Abstract]
Less than twelve months, fair value	7,006	6,005
Debt securities, held-to-maturity, continuous unrealized loss position, less than 12 months, accumulated loss	(170)	(94)
Twelve months or longer, fair value	117,016	122,272
Debt securities, held-to-maturity, continuous unrealized loss position, 12 months or longer, accumulated loss	(19,282)	(17,406)
Total, fair value	124,022	128,277
Debt securities, held-to-maturity, unrealized loss position, accumulated loss	(19,452)	(17,500)
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Less than twelve months, fair value	9,515	16,992
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(37)	(65)
Twelve months or longer, fair value	244,887	238,053
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(39,162)	(35,362)
Total, fair value	254,402	255,045
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(39,199)	(35,427)
State and political subdivisions
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Less than twelve months, fair value		1,029
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss		(1)
Twelve months or longer, fair value		0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss		0
Total, fair value		1,029
Available-for-sale securities, continuous unrealized loss position, accumulated loss		(1)
Collateralized mortgage obligations
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Less than twelve months, fair value	0	0
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	0	0
Twelve months or longer, fair value	1,927	2,001
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(193)	(200)
Total, fair value	1,927	2,001
Available-for-sale securities, continuous unrealized loss position, accumulated loss	(193)	(200)
Corporate bonds
Debt Securities, Available-for-sale, Unrealized Gain (Loss) [Abstract]
Less than twelve months, fair value	499	780
Available-for-sale securities, continuous unrealized loss position, less than 12 months, accumulated loss	(1)	(1)
Twelve months or longer, fair value	4,995	0
Available-for-sale securities, continuous unrealized loss position, 12 months or longer, accumulated loss	(5)	0
Total, fair value	5,494	780
Available-for-sale securities, continuous unrealized loss position, accumulated loss	$ (6)	$ (1)

No definition available.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

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