| **Loans and Allowance for Credit Losses - Age Analysis of Past Due Loans by Segment (Detail) (USD $)In Thousands, unless otherwise specified** | Mar. 31, 2015                                                                                                                                                                                                                                                                                       | Dec. 31, 2014                                                                                                                                                                                                                                                                                     | Mar. 31, 2014                                                |
|------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------------------------------------------------------------|
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | $ 33,565us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus                                                                                                                                                                                                                               | $ 42,667us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus                                                                                                                                                                                                                             |                                                         |
| Total past due and nonaccrual                                                                                                                  | 48,002us-gaap_FinancingReceivableRecordedInvestmentPastDue                                                                                                                                                                                                                                          | 61,449us-gaap_FinancingReceivableRecordedInvestmentPastDue                                                                                                                                                                                                                                        |                                                         |
| Current                                                                                                                                        | 4,389,599us-gaap_FinancingReceivableRecordedInvestmentCurrent                                                                                                                                                                                                                                       | 4,395,859us-gaap_FinancingReceivableRecordedInvestmentCurrent                                                                                                                                                                                                                                     |                                                         |
| Total                                                                                                                                          | 4,437,601us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome                                                                                                                                                                                                                                        | 4,457,308us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome                                                                                                                                                                                                                                      | 4,252,213us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome |
| Commercial, financial, agricultural and other [Member]                                                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | 18,654us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                             | 27,007us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                           |                                                         |
| Total past due and nonaccrual                                                                                                                  | 19,415us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                      | 30,300us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                    |                                                         |
| Current                                                                                                                                        | 1,047,373us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                   | 1,021,809us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                 |                                                         |
| Total                                                                                                                                          | 1,066,788us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                    | 1,052,109us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember                                                                                                                                  |                                                         |
| Real estate construction [Member]                                                                                                              |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | 236us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                             | 236us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                           |                                                         |
| Total past due and nonaccrual                                                                                                                  | 236us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                      | 237us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                    |                                                         |
| Current                                                                                                                                        | 107,646us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                  | 120,548us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                |                                                         |
| Total                                                                                                                                          | 107,882us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                   | 120,785us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember                                                                                                                                 |                                                         |
| Residential real estate [Member]                                                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | 7,583us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                 | 7,900us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                               |                                                         |
| Total past due and nonaccrual                                                                                                                  | 14,890us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                         | 15,434us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                       |                                                         |
| Current                                                                                                                                        | 1,195,621us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                      | 1,210,910us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                    |                                                         |
| Total                                                                                                                                          | 1,210,511us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                       | 1,226,344us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember                                                                                                                     |                                                         |
| Commercial Real Estate [Member]                                                                                                                |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | 6,831us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                        | 7,306us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                      |                                                         |
| Total past due and nonaccrual                                                                                                                  | 8,620us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                                 | 9,225us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                               |                                                         |
| Current                                                                                                                                        | 1,391,656us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                             | 1,396,031us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                           |                                                         |
| Total                                                                                                                                          | 1,400,276us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                              | 1,405,256us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember                                                                                                            |                                                         |
| Loans to individuals [Member]                                                                                                                  |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Nonaccrual                                                                                                                                     | 261us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                  | 218us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                |                                                         |
| Total past due and nonaccrual                                                                                                                  | 4,841us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                         | 6,253us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                       |                                                         |
| Current                                                                                                                                        | 647,303us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                       | 646,561us-gaap_FinancingReceivableRecordedInvestmentCurrent/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                     |                                                         |
| Total                                                                                                                                          | 652,144us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                        | 652,814us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember                                                                                                                                      |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member]                                                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 8,082us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                                                                                                                       | 13,473us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                                                                                                                    |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial, financial, agricultural and other [Member]                                |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 292us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                     | 2,816us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                 |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member] | Real estate construction [Member]                                                     |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                    | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                  |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member] | Residential real estate [Member]                                                      |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 3,815us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                      | 5,162us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                    |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Real Estate [Member]                                                       |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 1,283us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember             | 1,797us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember           |                                                         |
| Financing Receivables, 30 to 59 Days Past Due [Member] | Loans to individuals [Member]                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 2,692us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                     | 3,698us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables30To59DaysPastDueMember                                   |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member]                                                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 2,110us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                                                                                                                       | 2,690us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                                                                                                                     |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial, financial, agricultural and other [Member]                                |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 320us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                     | 213us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                   |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member] | Real estate construction [Member]                                                     |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                    | 1us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                  |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member] | Residential real estate [Member]                                                      |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 1,054us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                      | 1,295us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                    |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Real Estate [Member]                                                       |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 124us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember               | 122us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember             |                                                         |
| Financing Receivables, 60 to 89 Days Past Due [Member] | Loans to individuals [Member]                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 612us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                       | 1,059us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivables60To89DaysPastDueMember                                   |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member]                                                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 4,245us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                                                                                                                         | 2,619us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                                                                                                                       |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial, financial, agricultural and other [Member]                |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 149us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                       | 264us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                     |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Real estate construction [Member]                                     |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                      | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConstructionLoansMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                    |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Residential real estate [Member]                                      |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 2,438us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember        | 1,077us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ResidentialPortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember      |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Real Estate [Member]                                       |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | 382us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember | 0us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_CommercialRealEstatePortfolioSegmentMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember |                                                         |
| Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Loans to individuals [Member]                                         |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| **Accounts, Notes, Loans and Financing Receivable [Line Items]**                                                                               |                                                                                                                                                                                                                                                                                                |                                                                                                                                                                                                                                                                                              |                                                         |
| Total past due and nonaccrual                                                                                                                  | $ 1,276us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                     | $ 1,278us-gaap_FinancingReceivableRecordedInvestmentPastDue/ us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis= us-gaap_ConsumerLoanMember/ us-gaap_FinancingReceivablesPeriodPastDueAxis= us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember                   |                                                         |

| X                                                                                                                                                                            |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesAndLoansReceivableLineItems**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Financing receivables that are current.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 7A -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953401-111524
+ Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentCurrent**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| 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=49124121&loc=d3e5111-111524
+ Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentNonaccrualStatus**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Recorded Investment in financing receivables that are past due at 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 7A -URI http://asc.fasb.org/extlink&oid=49124121&loc=SL6953401-111524
+ Details**Name:**us-gaap_FinancingReceivableRecordedInvestmentPastDue**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5074-111524Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522
+ Details**Name:**us-gaap_LoansAndLeasesReceivableNetOfDeferredIncome**Namespace Prefix:**us-gaap_**Data Type:**xbrli:monetaryItemType**Balance Type:**debit**Period Type:**instant |
| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialLoanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                               |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                            |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConstructionLoansMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ConsumerLoanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                      |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=us-gaap_ResidentialPortfolioSegmentMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables30To59DaysPastDueMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                         |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivables60To89DaysPastDueMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                                                                       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_FinancingReceivablesPeriodPastDueAxis=us-gaap_FinancingReceivablesEqualToGreaterThan90DaysPastDueMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |