Supplemental Comprehensive Income Disclosures - Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Accumulated Other Comprehensive Income (Loss) [Line Items]
Unrealized holding gains (losses) on securities arising during the period	$ 33,737	$ (8,131)	$ 18,499
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax	7,150	(1,766)	3,449
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax	26,587	(6,365)	15,050
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax	(4,348)	(5,446)	(103)
Less: reclassification adjustment for (gains) losses on securities included in net income, Tax (Expense) Benefit	(913)	(1,144)	(22)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax	(3,435)	(4,302)	(81)
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment, before Tax	(38,085)	2,685	(18,602)
Total Unrealized (Losses) Gains on Securities, Tax (Expense) Benefit	(8,063)	622	(3,471)
OCI, Debt Securities, Available-for-Sale, Gain (Loss), after Adjustment and Tax	(30,022)	2,063	(15,131)
Unrealized holding gains on derivatives arising during the period	9,987	14,379	13,462
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax	(2,137)	(3,069)	(2,733)
Unrealized holding gains on derivatives arising during the period, Net of Tax Amount	7,850	11,310	10,729
Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, before Tax	(9,987)	(14,379)	(13,462)
Total unrealized gains on derivatives, Tax (Expense) Benefit	(2,137)	(3,069)	(2,733)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax	76	76	76
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax	(16)	(16)	(15)
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	60	60	61
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax	23	83	(22)
Net (loss) gain, Tax (Expense) Benefit	5	18	(7)
Net gain	(18)	(65)	15
Total Unrealized Gains (Losses) for Postretirement Obligations, Before Tax	53	(7)	98
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	11	(2)	22
Total Unrealized Gains (Losses) for Postretirement Obligations, Net of Tax	42	(5)	76
Total other comprehensive (loss) income, Pretax Amount	48,125	11,687	32,162
Other Comprehensive Income (Loss), Tax	10,211	2,445	6,226
Total other comprehensive (loss) Income	37,914	9,242	25,936
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax	7,850	11,310	10,729
Post-Retirement Obligation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax	60	60	61
Net gain	(18)
Total other comprehensive (loss) Income	$ 42	$ (5)	$ 76