| **Loans and Allowance - Composition of Impaired Loans by Loan Class (Details) - USD ($) $ in Thousands** | 3 Months Ended |           |
|----------------------------------------------------------------------------------------------------------|----------------|-----------|
||
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 131,555      |      | $ 134,581 |
| Impaired loans with related allowance                                                                    | 5,613          |      | 7,953 |
| Total Impaired Loans                                                                                     | 137,168        |      | 142,534 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 88,827         |      | 90,975 |
| Impaired loans with related allowance                                                                    | 5,122          |      | 6,552 |
| Total Impaired Loans                                                                                     | 93,949         |      | 97,527 |
| Related Allowance                                                                                        | 1,373          |      | 1,842 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 90,462         | $ 103,092 |   |
| Impaired loans with related allowance                                                                    | 5,313          | 13,244    |   |
| Total Impaired Loans                                                                                     | 95,775         | 116,336   |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | 1,124          | 1,172     |   |
| Impaired loans with related allowance                                                                    | 9              | 10        |   |
| Total Impaired Loans                                                                                     | 1,133          | 1,182     |   |
| Commercial and industrial loans                                                                          |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | 21,751         |      | 22,151 |
| Impaired loans with related allowance                                                                    | 1,610          |      | 3,043 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 11,559         |      | 11,669 |
| Impaired loans with related allowance                                                                    | 1,357          |      | 2,690 |
| Related Allowance                                                                                        | 620            |      | 1,247 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 12,052         | 16,150    |   |
| Impaired loans with related allowance                                                                    | 1,363          | 4,379     |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | 109            | 139       |   |
| Impaired loans with related allowance                                                                    | 9              | 10        |   |
| Agricultural production financing and other loans to farmers                                             |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | 724            |      | 370 |
| Impaired loans with related allowance                                                                    | 1,150          |      | 466 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 716            |      | 361 |
| Impaired loans with related allowance                                                                    | 1,150          |      | 466 |
| Related Allowance                                                                                        | 415            |      | 30 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 716            | 303       |   |
| Impaired loans with related allowance                                                                    | 1,315          | $ 3,991   |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 1            |           |   |
| Impaired loans with related allowance                                                                    |                |           |   |
| Real estate loans - Construction                                                                         |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 8,482        |      | 4,551 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 4,300          |      | 2,336 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 4,262          | $ 8,542   |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | 85             | 104       |   |
| Real estate loans - Commercial and farmland                                                              |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | 88,293         |      | 95,930 |
| Impaired loans with related allowance                                                                    | 1,907          |      | 2,144 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 64,710         |      | 69,024 |
| Impaired loans with related allowance                                                                    | 1,738          |      | 1,933 |
| Related Allowance                                                                                        | 242            |      | 392 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 65,461         | 69,036    |   |
| Impaired loans with related allowance                                                                    | 1,756          | 3,113     |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 871          | $ 878     |   |
| Impaired loans with related allowance                                                                    |                |           |   |
| Real estate loans - Residential                                                                          |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 11,991       |      | 11,262 |
| Impaired loans with related allowance                                                                    | 946            |      | 2,300 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 7,317          |      | 7,338 |
| Impaired loans with related allowance                                                                    | 877            |      | 1,463 |
| Related Allowance                                                                                        | 96             |      | 173 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | 7,746          | $ 8,528   |   |
| Impaired loans with related allowance                                                                    | 879            | 1,761     |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 58           | $ 48      |   |
| Impaired loans with related allowance                                                                    |                |           |   |
| Real estate loans - Home equity                                                                          |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 296          |      | 297 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 | 225            |      | 247 |
| **Average Recorded Investment**                                                                          |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 225          | $ 533     |   |
| **Interest Income Recognized**                                                                           |           |      |   |
| Impaired loans with no related allowance                                                                 |                | $ 3       |   |
| Other commercial loans                                                                                   |           |      |   |
| **Unpaid Principal Balance**                                                                             |           |      |   |
| Impaired loans with no related allowance                                                                 | $ 18           |      | $ 20 |
| **Recorded Investment**                                                                                  |           |      |   |
| Impaired loans with no related allowance                                                                 |                |      |  |

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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.
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