Securities - Available for Sale Securities (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost, Total securities available for sale	$ 672,892	$ 682,351
Gross Unrealized Gains	3,059	819
Gross Unrealized Losses	(57,679)	(67,768)
Fair Value	618,272	615,402
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost, Total securities available for sale	71,418	66,495
Gross Unrealized Gains	315	20
Gross Unrealized Losses	(4,075)	(5,486)
Fair Value	67,658	61,029
Obligations of States and Political Subdivisions [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost, Total securities available for sale	359,452	350,104
Gross Unrealized Gains	2,725	784
Gross Unrealized Losses	(23,578)	(33,640)
Fair Value	338,599	317,248
Mortgage-back Securities in Government Sponsored Entities [Member]
Debt Securities, Available-for-Sale [Line Items]
Amortized Cost, Total securities available for sale	242,022	265,752
Gross Unrealized Gains	19	15
Gross Unrealized Losses	(30,026)	(28,642)
Fair Value	$ 212,015	$ 237,125