| **Loans and Allowance - Summary of Non-Accrual Loans by Loan Class (Details) (USD $)In Thousands, unless otherwise specified** | Jun. 30, 2014 | Dec. 31, 2013 |
|--------------------------------------------------------------------------------------------------------------------------------|---------------|---------------|
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | $ 51,289      | $ 56,402      |
| Commercial and industrial loans                                                                                                |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 7,400         | 9,283         |
| Agricultural production financing and other loans to farmers                                                                   |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 26            | 30            |
| Real estate loans - Construction                                                                                               |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 2,914         | 4,978         |
| Real estate loans - Commercial and farm land                                                                                   |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 25,003        | 28,095        |
| Real estate loans - Residential                                                                                                |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 13,343        | 12,068        |
| Real estate loans - Home equity                                                                                                |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 2,433         | 1,667         |
| Individuals' loans for household and other personal expenditures                                                               |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              | 170           | 117           |
| Other loans                                                                                                                    |          |          |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                               |          |          |
| Non-accrual loans                                                                                                              |     | $ 164         |

| X                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesAndLoansReceivableLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5111-111524
+ Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |