Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Investment Securities [Line Items]
Total debt securities, Amortized Cost	$ 898,702	$ 1,045,579
Gross Unrealized Gains	275	9,515
Gross Unrealized Losses	(136,316)	(13,714)
Securities available for sale	762,661	1,041,380
US States and Political Subdivisions Debt Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	9,482	9,538
Gross Unrealized Gains	0	89
Gross Unrealized Losses	(1,295)	(103)
Securities available for sale	8,187	9,524
Corporate Securities [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	32,010	32,088
Gross Unrealized Gains	179	973
Gross Unrealized Losses	(2,985)	(112)
Securities available for sale	29,204	32,949
Obligations of U.S. Government-Sponsored Enterprises [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	527,800
Securities available for sale	449,000
Obligations of U.S. Government-Sponsored Enterprises [Member] \| Mortgage - Backed Securities - Residential [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	527,777	632,687
Gross Unrealized Gains	59	6,308
Gross Unrealized Losses	(78,847)	(9,021)
Securities available for sale	448,989	629,974
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	(118)	(19)
Securities available for sale	882	981
Obligations of U.S. Government [Member] \| Mortgage - Backed Securities - Commercial [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	324,306	365,024
Gross Unrealized Gains	0	1,725
Gross Unrealized Losses	(52,890)	(4,459)
Securities available for sale	271,416	362,290
Obligations of U.S. Government [Member] \| Mortgage - Backed Securities - Residential [Member]
Investment Securities [Line Items]
Total debt securities, Amortized Cost	4,127	5,242
Gross Unrealized Gains	37	420
Gross Unrealized Losses	(181)	0
Securities available for sale	$ 3,983	$ 5,662

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
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-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(6))
-URI https://asc.fasb.org/extlink&oid=126897435&loc=d3e534808-122878

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
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-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
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-Section 45
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-URI https://asc.fasb.org/extlink&oid=126970911&loc=d3e27161-111563

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