Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Investment Securities [Line Items]
Total debt securities, Amortized Cost	$ 1,138,425	$ 898,702
Gross Unrealized Gains	8,182	275
Gross Unrealized Losses	(125,621)	(136,316)
Securities available for sale	1,020,986	762,661
US States and Political Subdivisions Debt Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	9,226	9,482
Gross Unrealized Gains	3	0
Gross Unrealized Losses	(1,027)	(1,295)
Securities available for sale	8,202	8,187
Corporate Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	51,886	32,010
Gross Unrealized Gains	145	179
Gross Unrealized Losses	(3,619)	(2,985)
Securities available for sale	48,412	29,204
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	559,800
Securities available for sale	494,600
Obligations of U.S. Government-Sponsored Enterprises [Member] \| Mortgage - Backed Securities - Residential [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	559,769	527,777
Gross Unrealized Gains	3,052	59
Gross Unrealized Losses	(68,222)	(78,847)
Securities available for sale	494,599	448,989
Obligations of U.S. Government-Sponsored Enterprises [Member] \| Other Government - Sponsored Enterprises [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	1,000	1,000
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(85)	(118)
Securities available for sale	915	882
Obligations of U.S. Government [Member] \| Mortgage - Backed Securities - Commercial [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	512,979	324,306
Gross Unrealized Gains	4,935	0
Gross Unrealized Losses	(52,521)	(52,890)
Securities available for sale	465,393	271,416
Obligations of U.S. Government [Member] \| Mortgage - Backed Securities - Residential [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	3,565	4,127
Gross Unrealized Gains	47	37
Gross Unrealized Losses	(147)	(181)
Securities available for sale	$ 3,465	$ 3,983

Investment Securities [Line Items]

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- Definition

Amortized cost of 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://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

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Amount of unrealized gain 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://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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Amount of unrealized loss 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://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

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Amount of 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://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (aa)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481800/320-10-50-2

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481830/320-10-45-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479853/942-210-S99-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479130/326-30-45-1

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