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Loans (ALLL) - Additional Information (Detail) - USD ($) $ in Thousands | Sep. 30, 2020 | Jun. 30, 2020 | Dec. 31, 2019 | Sep. 30, 2019 | Jun. 30, 2019 | Dec. 31, 2018
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Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Accretable yield related to acquisition | $ 1,759 | $ 1,871 | $ 2,021 | $ 2,245 | $ 2,329 | $ 2,544
Bank of Geneva [Member] |  |  |  |  |  |
Accounts, Notes, Loans and Financing Receivable [Line Items] |  |  |  |  |  |
Accretable yield related to acquisition | $ 1,700 |  | $ 2,000 |  |  |

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- Definition The aggregate excess of a loan's cash flows expected to be collected over the investor's initial investment in the loan for loans accounted for as debt securities, with evidence of deterioration of credit quality since origination that were acquired by completion of a transfer for which it is probable, at acquisition, that the investor will be unable to collect all contractually required payments receivable. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 15 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=121585399&loc=d3e13503-111538 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 30 -Section 50 -Paragraph 2 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=121614798&loc=d3e15032-111544 + Details
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