Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	$ (499)	$ (6,965)
Fair Value, Less Than Twelve Months	14,126	99,357
Gross Unrealized Losses, Twelve Months and Over	(45,042)	(41,501)
Fair Value, Twelve Months and Over	344,860	286,095
Gross Unrealized Losses, Total	(45,541)	(48,466)
Fair Value, Total	358,986	385,452
U.S. Treasury [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(11)	(207)
Fair Value, Less Than Twelve Months	487	9,121
Gross Unrealized Losses, Twelve Months and Over	(8,896)	(9,622)
Fair Value, Twelve Months and Over	85,640	85,557
Gross Unrealized Losses, Total	(8,907)	(9,829)
Fair Value, Total	86,127	94,678
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	(16,157)	(15,969)
Fair Value, Twelve Months and Over	127,891	114,906
Gross Unrealized Losses, Total	(16,157)	(17,050)
Fair Value, Total	127,891	139,466
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(124)	(2,454)
Fair Value, Less Than Twelve Months	2,826	26,905
Gross Unrealized Losses, Twelve Months and Over	(13,586)	(11,687)
Fair Value, Twelve Months and Over	78,830	60,022
Gross Unrealized Losses, Total	(13,710)	(14,141)
Fair Value, Total	81,656	86,927
State and Local Governments [Member]
Schedule of Available-for-sale Securities [Line Items]
Gross Unrealized Losses, Less Than Twelve Months	(364)	(3,223)
Fair Value, Less Than Twelve Months	10,813	38,771
Gross Unrealized Losses, Twelve Months and Over	(6,403)	(4,223)
Fair Value, Twelve Months and Over	52,499	25,610
Gross Unrealized Losses, Total	(6,767)	(7,446)
Fair Value, Total	$ 63,312	$ 64,381