Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	$ (26)	$ (6,965)
Fair Value, Less Than Twelve Months	5,797	99,357
Gross Unrealized Losses, Twelve Months and Over	(36,835)	(41,501)
Fair Value, Twelve Months and Over	345,911	286,095
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(4)	(207)
Fair Value, Less Than Twelve Months	494	9,121
Gross Unrealized Losses, Twelve Months and Over	(6,909)	(9,622)
Fair Value, Twelve Months and Over	79,528	85,557
U.S. Government Agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months		(1,081)
Fair Value, Less Than Twelve Months		24,560
Gross Unrealized Losses, Twelve Months and Over	(12,738)	(15,969)
Fair Value, Twelve Months and Over	128,222	114,906
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(20)	(2,454)
Fair Value, Less Than Twelve Months	4,372	26,905
Gross Unrealized Losses, Twelve Months and Over	(11,909)	(11,687)
Fair Value, Twelve Months and Over	77,759	60,022
State and Local Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(2)	(3,223)
Fair Value, Less Than Twelve Months	931	38,771
Gross Unrealized Losses, Twelve Months and Over	(5,279)	(4,223)
Fair Value, Twelve Months and Over	$ 60,402	$ 25,610