Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Jun. 30, 2023	Dec. 31, 2022
Investment Securities [Line Items]
Amortized Cost	$ 877,909	$ 898,702
Gross Unrealized Gains	57	275
Gross Unrealized Losses	(139,857)	(136,316)
Debt Securities, Available-for-Sale	738,109	762,661
US Government Agencies Residential Mortgage-backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	3,851	4,127
Gross Unrealized Gains	23	37
Gross Unrealized Losses	(167)	(181)
Debt Securities, Available-for-Sale	3,707	3,983
US Government Agency Debt Securities Commercial [Member]
Investment Securities [Line Items]
Amortized Cost	337,197	324,306
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(57,545)	(52,890)
Debt Securities, Available-for-Sale	279,652	271,416
Residential Mortgage Backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	496,213	527,777
Gross Unrealized Gains	34	59
Gross Unrealized Losses	(77,025)	(78,847)
Debt Securities, Available-for-Sale	419,222	448,989
US Government-sponsored Enterprises Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	1,000	1,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(117)	(118)
Debt Securities, Available-for-Sale	883	882
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Amortized Cost	9,231	9,482
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,217)	(1,295)
Debt Securities, Available-for-Sale	8,014	8,187
Corporate Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	30,417	32,010
Gross Unrealized Gains	0	179
Gross Unrealized Losses	(3,786)	(2,985)
Debt Securities, Available-for-Sale	$ 26,631	$ 29,204