Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Investment Securities [Line Items]
Amortized Cost	$ 876,298	$ 898,702
Gross Unrealized Gains	138	275
Gross Unrealized Losses	(125,823)	(136,316)
Debt Securities, Available-for-Sale	750,613	762,661
US Government Agencies Residential Mortgage-backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	3,995	4,127
Gross Unrealized Gains	45	37
Gross Unrealized Losses	(144)	(181)
Debt Securities, Available-for-Sale	3,896	3,983
US Government Agency Debt Securities Commercial [Member]
Investment Securities [Line Items]
Amortized Cost	319,133	324,306
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(49,250)	(52,890)
Debt Securities, Available-for-Sale	269,883	271,416
Residential Mortgage Backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	512,277	527,777
Gross Unrealized Gains	72	59
Gross Unrealized Losses	(72,106)	(78,847)
Debt Securities, Available-for-Sale	440,243	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	(107)	(118)
Debt Securities, Available-for-Sale	893	882
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Amortized Cost	9,479	9,482
Gross Unrealized Gains	1	0
Gross Unrealized Losses	(1,075)	(1,295)
Debt Securities, Available-for-Sale	8,405	8,187
Corporate Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	30,414	32,010
Gross Unrealized Gains	20	179
Gross Unrealized Losses	(3,141)	(2,985)
Debt Securities, Available-for-Sale	$ 27,293	$ 29,204