Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Investment Securities [Line Items]
Amortized Cost	$ 994,657	$ 1,045,579
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	1,236	9,515
Gross Unrealized Losses	(62,689)	(13,714)
Securities available for sale, at fair value	933,204	1,041,380
Available-for-sale Securities, Current	933,204	1,041,380
US Government Agencies Residential Mortgage-backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	4,884	5,242
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	198	420
Gross Unrealized Losses	(16)	0
Available-for-sale Securities, Current	5,066	5,662
US Government Agency Debt Securities Commercial [Member]
Investment Securities [Line Items]
Amortized Cost	350,918	365,024
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	25	1,725
Gross Unrealized Losses	(21,715)	(4,459)
Available-for-sale Securities, Current	329,228	362,290
Residential Mortgage Backed Securities [Member]
Investment Securities [Line Items]
Amortized Cost	596,272	632,687
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	504	6,308
Gross Unrealized Losses	(39,517)	(9,021)
Available-for-sale Securities, Current	557,259	629,974
US Government-sponsored Enterprises Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	1,000	1,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	0	0
Gross Unrealized Losses	(65)	(19)
Available-for-sale Securities, Current	935	981
Obligations of States and Political Subdivisions [Member]
Investment Securities [Line Items]
Amortized Cost	9,515	9,538
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	21	89
Gross Unrealized Losses	(614)	(103)
Available-for-sale Securities, Current	8,922	9,524
Corporate Debt Securities [Member]
Investment Securities [Line Items]
Amortized Cost	32,068	32,088
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	488	973
Gross Unrealized Losses	(762)	(112)
Available-for-sale Securities, Current	$ 31,794	$ 32,949

Investment Securities [Line Items]

No definition available.

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- Definition

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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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- Definition

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).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

+ Details

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- Definition

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

+ References

No definition available.

+ Details

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- Definition

This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any.

+ References

No definition available.

+ Details

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- Definition

Amount of investment in debt and equity securities categorized neither as trading securities nor held-to-maturity securities and intended be sold or mature one year or operating cycle, if longer.

+ References

No definition available.

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