| **Loans and Allowance - Composition of Impaired Loans by Loan Class (Details) - USD ($) $ in Thousands** | 12 Months Ended |
|----------------------------------------------------------------------------------------------------------|-----------------|
||
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | $ 100,416       | $ 134,581 | $ 158,563 |
| Impaired loans with related allowance                                                                    | 4,963           | 7,953 | 16,703 |
| Total Impaired Loans                                                                                     | 105,379         | 142,534 | 175,266 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 68,371          | 90,975 | 102,793 |
| Impaired loans with related allowance                                                                    | 3,679           | 6,552 | 13,430 |
| Total Impaired Loans                                                                                     | 72,050          | 97,527 | 116,223 |
| Related Allowance                                                                                        | 612             | 1,842 | 2,769 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 74,592          | 96,423 | 106,807 |
| Impaired loans with related allowance                                                                    | 3,718           | 6,945 | 15,764 |
| Total Impaired Loans                                                                                     | 78,310          | 103,368 | 122,571 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 3,905           | 4,217 | 4,297 |
| Impaired loans with related allowance                                                                    |                 | 38 | 65 |
| Total Impaired Loans                                                                                     | 3,905           | 4,255 | 4,362 |
| Commercial and industrial loans                                                                          |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 17,645          | 22,151 | 35,514 |
| Impaired loans with related allowance                                                                    |            | 3,043 | 1,766 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 10,074          | 11,669 | 18,029 |
| Impaired loans with related allowance                                                                    |            | 2,690 | 1,684 |
| Related Allowance                                                                                        |            | 1,247 | 1,055 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 13,393          | 12,578 | 18,711 |
| Impaired loans with related allowance                                                                    |            | 2,752 | 1,721 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 499             | 488 | 362 |
| Impaired loans with related allowance                                                                    |            | 38 | 40 |
| Agriculture production financing and other loans to farmers                                              |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 757             | 370 | 26 |
| Impaired loans with related allowance                                                                    | 660             | 466 | 6,777 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 680             | 361 | 22 |
| Impaired loans with related allowance                                                                    | 660             | 466 | 5,777 |
| Related Allowance                                                                                        | 36              | 30 | 400 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 750             | 439 | 26 |
| Impaired loans with related allowance                                                                    | 691             | 538 | 8,044 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 3               |   |   |
| Impaired loans with related allowance                                                                    |                 |  | 1 |
| Construction                                                                                             |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 5,946           | 4,551 | 12,956 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 3,178           | 2,336 | 9,318 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 3,255           | 3,662 | 9,837 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 258             | 157 | 427 |
| Commercial and farmland                                                                                  |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 67,936          | 95,930 | 95,856 |
| Impaired loans with related allowance                                                                    | 4,238           | 2,144 | 7,159 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 49,731          | 69,024 | 68,187 |
| Impaired loans with related allowance                                                                    | 2,985           | 1,933 | 4,971 |
| Related Allowance                                                                                        | 553             | 392 | 1,120 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 51,740          | 71,569 | 70,844 |
| Impaired loans with related allowance                                                                    | 2,989           | 1,868 | 4,999 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 2,978           | 3,328 | 3,389 |
| Impaired loans with related allowance                                                                    |                 |  | 24 |
| Residential                                                                                              |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 8,039           | 11,262 | 10,591 |
| Impaired loans with related allowance                                                                    | 65              | 2,300 | 1,001 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 4,664           | 7,338 | 6,839 |
| Impaired loans with related allowance                                                                    | 34              | 1,463 | 998 |
| Related Allowance                                                                                        | 23              | 173 | 194 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 5,410           | 7,926 | 6,987 |
| Impaired loans with related allowance                                                                    | 38              | 1,787 | 1,000 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 | 167             | 244 | 119 |
| Impaired loans with related allowance                                                                    |                 |  |  |
| Home equity                                                                                              |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 82              | 297 | 3,590 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 | 44              | 247 | 398 |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 | 44              | 249 | 402 |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 |                 |  |  |
| Other commercial loans                                                                                   |            |   |   |
| **Unpaid Principal Balance**                                                                             |            |   |   |
| Impaired loans with no related allowance                                                                 | 11              | 20 | 30 |
| **Recorded Investment**                                                                                  |            |   |   |
| Impaired loans with no related allowance                                                                 |                 |  |  |
| **Average Recorded Investment**                                                                          |            |   |   |
| Impaired loans with no related allowance                                                                 |                 |  |  |
| **Interest Income Recognized**                                                                           |            |   |   |
| Impaired loans with no related allowance                                                                 |                 |  |  |

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|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
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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