Securities - Amortized Cost and Fair Value of Securities with Gross Unrealized Gains and Losses (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 395,203	$ 439,186
Gross Unrealized Gains	136	69
Gross Unrealized Losses	(36,861)	(48,466)
Fair Value	358,478	390,789
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	87,182	104,507
Gross Unrealized Gains	1
Gross Unrealized Losses	(6,913)	(9,829)
Fair Value	80,270	94,678
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	140,960	156,817
Gross Unrealized Losses	(12,738)	(17,050)
Fair Value	128,222	139,767
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	94,061	101,068
Gross Unrealized Losses	(11,929)	(14,141)
Fair Value	82,132	86,927
State and Local Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	73,000	76,794
Gross Unrealized Gains	135	69
Gross Unrealized Losses	(5,281)	(7,446)
Fair Value	$ 67,854	$ 69,417