| **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                                                                 | $ 23,414       |     | $ 14,555 |
| Impaired loans with related allowance                                                                    | 4,567          |     | 10,501 |
| Total Impaired Loans                                                                                     | 27,981         |     | 25,056 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 19,415         |     | 11,594 |
| Impaired loans with related allowance                                                                    | 4,472          |     | 10,431 |
| Total Impaired Loans                                                                                     | 23,887         |     | 22,025 |
| Related Allowance                                                                                        | 1,599          |     | 1,872 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 20,149         | $ 17,714 |   |
| Impaired loans with related allowance                                                                    | 4,576          | 4,598    |   |
| Total Impaired Loans                                                                                     | 24,725         | 22,312   |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 40             | 54       |   |
| Impaired loans with related allowance                                                                    | 18             | 14       |   |
| Total Impaired Loans                                                                                     | 58             | 68       |   |
| Commercial and industrial loans                                                                          |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 1,920          |     | 828 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 1,626          |     | 806 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 1,641          | 1,845    |   |
| Impaired loans with related allowance                                                                    | 0              | 465      |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 0              | 0        |   |
| Impaired loans with related allowance                                                                    | 0              | 0        |   |
| Agricultural production financing and other loans to farmers                                             |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 807            |     | 679 |
| Impaired loans with related allowance                                                                    | 2,167          |     |   |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 792            |     | 679 |
| Impaired loans with related allowance                                                                    | 2,117          |     |   |
| Related Allowance                                                                                        | 1,172          |     |   |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 799            | 640      |   |
| Impaired loans with related allowance                                                                    | 2,150          | 0        |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 0              | 0        |   |
| Impaired loans with related allowance                                                                    | 0              | 0        |   |
| Construction                                                                                             |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 9,330          |     | 1,352 |
| Impaired loans with related allowance                                                                    |           |     | 7,978 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 7,524          |     | 614 |
| Impaired loans with related allowance                                                                    |           |     | 7,977 |
| Related Allowance                                                                                        |           |     | 1,429 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 8,270          | 0        |   |
| Impaired loans with related allowance                                                                    | 0              | 1,352    |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 0              | 0        |   |
| Commercial and farmland                                                                                  |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 10,838         |     | 11,176 |
| Impaired loans with related allowance                                                                    | 171            |     | 171 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 8,973          |     | 8,994 |
| Impaired loans with related allowance                                                                    | 171            |     | 171 |
| Related Allowance                                                                                        | 6              |     | 6 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 8,999          | 14,450   |   |
| Impaired loans with related allowance                                                                    | 171            | 767      |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 39             | 48       |   |
| Residential                                                                                              |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 118            |     | 118 |
| Impaired loans with related allowance                                                                    | 1,843          |     | 1,958 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 99             |     | 100 |
| Impaired loans with related allowance                                                                    | 1,815          |     | 1,907 |
| Related Allowance                                                                                        | 348            |     | 362 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 38             | 759      |   |
| Impaired loans with related allowance                                                                    | 1,884          | 1,709    |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 | 1              | 6        |   |
| Impaired loans with related allowance                                                                    | 15             | 12       |   |
| Home equity                                                                                              |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 48             |     | 49 |
| Impaired loans with related allowance                                                                    | 371            |     | 376 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 48             |     | 48 |
| Impaired loans with related allowance                                                                    | 354            |     | 358 |
| Related Allowance                                                                                        | 72             |     | 74 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 48             | 8        |   |
| Impaired loans with related allowance                                                                    | 356            | 305      |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 |           | 0        |   |
| Impaired loans with related allowance                                                                    | 3              | 2        |   |
| Individuals' loans for household and other personal expenditures                                         |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with related allowance                                                                    | 15             |     | 18 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with related allowance                                                                    | 15             |     | 18 |
| Related Allowance                                                                                        | 1              |     | 1 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | 1              | 12       |   |
| Impaired loans with related allowance                                                                    | 15             | 0        |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 |           | 0        |   |
| Impaired loans with related allowance                                                                    |           | 0        |   |
| Public finance and other commercial loans                                                                |           |     |   |
| **Unpaid Principal Balance**                                                                             |           |     |   |
| Impaired loans with no related allowance                                                                 | 353            |     | 353 |
| **Recorded Investment**                                                                                  |           |     |   |
| Impaired loans with no related allowance                                                                 | 353            |     | $ 353 |
| **Average Recorded Investment**                                                                          |           |     |   |
| Impaired loans with no related allowance                                                                 | $ 353          | 0        |   |
| **Interest Income Recognized**                                                                           |           |     |   |
| Impaired loans with no related allowance                                                                 |           | $ 0      |   |

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