| **Loans and Allowance - Summary of Troubled Debt Restructurings (Detail) (USD $)In Thousands, unless otherwise specified** | 12 Months Ended |
|----------------------------------------------------------------------------------------------------------------------------|-----------------|
||
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          | $ 7,753         | $ 15,194 |
| Post-Modification Recorded Balance                                                                                         | 6,757           | 14,723 |
| Number of Loans                                                                                                            | 32              | 50 |
| Commercial and industrial loans                                                                                            |            |   |
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          | 295             | 1,562 |
| Post-Modification Recorded Balance                                                                                         | 316             | 1,547 |
| Number of Loans                                                                                                            | 5               | 9 |
| Construction                                                                                                               |            |   |
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          |            | 794 |
| Post-Modification Recorded Balance                                                                                         |            | 653 |
| Number of Loans                                                                                                            |            | 2 |
| Commercial and farmland                                                                                                    |            |   |
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          | 6,506           | 10,366 |
| Post-Modification Recorded Balance                                                                                         | 5,492           | 10,154 |
| Number of Loans                                                                                                            | 11              | 14 |
| Residential                                                                                                                |            |   |
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          | 809             | 2,302 |
| Post-Modification Recorded Balance                                                                                         | 804             | 2,172 |
| Number of Loans                                                                                                            | 12              | 20 |
| Consumer                                                                                                                   |            |   |
| **Financing Receivable, Modifications [Line Items]**                                                                       |            |   |
| Pre-Modification Recorded Balance                                                                                          | 143             | 170 |
| Post-Modification Recorded Balance                                                                                         | $ 145           | $ 197 |
| Number of Loans                                                                                                            | 4               | 5 |

| X                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
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+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
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+ References
No definition available.
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| X                                                                                                                                                                                                                                                                                                                                                           |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing Receivable, Modifications, Pre-Modification Recorded Investment During Period
+ References
No definition available.
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| X                                                                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
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