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Loans - Impaired Loans Classified as Troubled Debt Restructured (Detail) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2020 USD ($) Contract Loan | Sep. 30, 2019 USD ($) Contract | Sep. 30, 2020 USD ($) Contract Loan | Sep. 30, 2019 USD ($) Contract | Dec. 31, 2019 Loan
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Loan | 1 |  | 6 |  | 5
Consumer Real Estate [Member] |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  | 1 |  | 1 |
Pre-Modification Outstanding Recorded Investment |  | $ 74 |  | $ 74 |
Post-Modification Outstanding Recorded Investment |  | $ 74 |  | $ 74 |
Commercial Real Estate [Member] |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  |  | 2 |  |
Pre-Modification Outstanding Recorded Investment |  |  | $ 981 |  |
Post-Modification Outstanding Recorded Investment |  |  | $ 981 |  |
Ag Real Estate [Member] |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  |  | 2 |  |
Pre-Modification Outstanding Recorded Investment |  |  | $ 5,380 |  |
Post-Modification Outstanding Recorded Investment |  |  | $ 5,380 |  |
Commercial and Industrial [Member] |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Contract | 1 |  | 1 | 4 |
Pre-Modification Outstanding Recorded Investment | $ 50 |  | $ 50 | $ 812 |
Post-Modification Outstanding Recorded Investment | $ 50 |  | $ 50 | $ 812 |
Agricultural [Member] |  |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  |  | 1 |  |
Pre-Modification Outstanding Recorded Investment |  |  | $ 164 |  |
Post-Modification Outstanding Recorded Investment |  |  | $ 164 |  |

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- Definition Number of financing receivables that have been modified by troubled debt restructurings. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524 + Details
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