Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2026	Dec. 31, 2025
Investment Securities [Line Items]
Amortized Cost	$ 1,129,910	$ 1,096,232
Gross Unrealized Gains	2,880	5,681
Gross Unrealized Losses	(90,391)	(87,719)
Debt Securities, Available-for-Sale	1,042,399	1,014,194
US Government Agencies Residential Mortgage-backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	2,543	2,638
Gross Unrealized Gains	20	23
Gross Unrealized Losses	(152)	(165)
Debt Securities, Available-for-Sale	2,411	2,496
US Government Agency Debt Securities Commercial [Member]
Investment Securities [Line Items]
Amortized Cost	709,359	701,572
Gross Unrealized Gains	1,647	3,788
Gross Unrealized Losses	(45,665)	(43,671)
Debt Securities, Available-for-Sale	665,341	661,689
Residential Mortgage Backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	367,198	336,493
Gross Unrealized Gains	679	1,087
Gross Unrealized Losses	(42,712)	(42,057)
Debt Securities, Available-for-Sale	325,165	295,523
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	(9)	(16)
Debt Securities, Available-for-Sale	991	984
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Amortized Cost	7,560	7,560
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(623)	(590)
Debt Securities, Available-for-Sale	6,937	6,971
Corporate Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	42,250	46,969
Gross Unrealized Gains	534	782
Gross Unrealized Losses	(1,230)	(1,220)
Debt Securities, Available-for-Sale	$ 41,554	$ 46,531

Investment Securities [Line Items]

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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