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Loans - Impaired Loans Classified as Troubled Debt Restructured (Detail) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 USD ($) Contract Loan | Jun. 30, 2020 USD ($) Contract Loan | Jun. 30, 2021 USD ($) Contract | Jun. 30, 2020 USD ($) Contract Loan
Financing Receivable Modifications [Line Items] |  |  |  |
Number of Contracts Modified in the Last three Months | Loan | 1 | 3 |  | 5
Agricultural Real Estate [Member] |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  | 2 |  | 2
Pre-Modification Outstanding Recorded Investment |  | $ 5,380 |  | $ 5,380
Post-Modification Outstanding Recorded Investment |  | $ 5,380 |  | $ 5,380
Agricultural [Member] |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |
Number of Contracts Modified in the Last three Months | Contract |  | 1 |  | 1
Pre-Modification Outstanding Recorded Investment |  | $ 164 |  | $ 164
Post-Modification Outstanding Recorded Investment |  | $ 164 |  | $ 164
Commercial Real Estate [Member] |  |  |  |
Financing Receivable Modifications [Line Items] |  |  |  |
Number of Contracts Modified in the Last three Months | Contract | 1 |  | 1 | 2
Pre-Modification Outstanding Recorded Investment | $ 382 |  | $ 382 | $ 981
Post-Modification Outstanding Recorded Investment | $ 382 |  | $ 382 | $ 981

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