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Investment Securities - Analysis of Amortized Cost and Estimated Fair Values of Securities Available for Sale (Detail) - USD ($) $ in Thousands | 12 Months Ended
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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

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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 + Details
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- Definition 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 + Details
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