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Loans and Allowance for Loan Losses - Activity in All by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2014 | Sep. 30, 2014 | Jun. 30, 2014 | Mar. 31, 2014 | Dec. 31, 2013 | Sep. 30, 2013 | Jun. 30, 2013 | Mar. 31, 2013 | Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | $ 39,034 us-gaap_LoansAndLeasesReceivableAllowance |  |  |  | $ 38,725 us-gaap_LoansAndLeasesReceivableAllowance | $ 39,034 us-gaap_LoansAndLeasesReceivableAllowance | $ 38,725 us-gaap_LoansAndLeasesReceivableAllowance |
Charge- offs |  |  |  |  |  |  |  |  | (2,619)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs | (1,560)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs |
Recoveries |  |  |  |  |  |  |  |  | 1,402 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery | 611 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery |
Net charge- offs |  |  |  |  |  |  |  |  | (1,217)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet | (949)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet |
Provisions charged to operations | 1,840 us-gaap_ProvisionForLoanAndLeaseLosses | (3,115)us-gaap_ProvisionForLoanAndLeaseLosses | 3,129 us-gaap_ProvisionForLoanAndLeaseLosses | 1,218 us-gaap_ProvisionForLoanAndLeaseLosses | 454 us-gaap_ProvisionForLoanAndLeaseLosses | (12)us-gaap_ProvisionForLoanAndLeaseLosses | 516 us-gaap_ProvisionForLoanAndLeaseLosses | 300 us-gaap_ProvisionForLoanAndLeaseLosses | 3,072 us-gaap_ProvisionForLoanAndLeaseLosses | 1,258 us-gaap_ProvisionForLoanAndLeaseLosses | 3,100 us-gaap_ProvisionForLoanAndLeaseLosses
Balance at end of period | 40,889 us-gaap_LoansAndLeasesReceivableAllowance |  |  |  | 39,034 us-gaap_LoansAndLeasesReceivableAllowance |  |  |  | 40,889 us-gaap_LoansAndLeasesReceivableAllowance | 39,034 us-gaap_LoansAndLeasesReceivableAllowance | 38,725 us-gaap_LoansAndLeasesReceivableAllowance
Non-residential Real Estate Owner Occupied [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 4,827 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |  |  |  | 5,104 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | 4,827 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | 5,104 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Charge- offs |  |  |  |  |  |  |  |  | (42)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | (3)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Recoveries |  |  |  |  |  |  |  |  | 102 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | 20 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Net charge- offs |  |  |  |  |  |  |  |  | 60 us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | 17 us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | (481)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | (294)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Balance at end of period | 4,406 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |  |  |  | 4,827 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |  |  |  | 4,406 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember | 4,827 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Non-residential Real Estate Other [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 11,026 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |  |  |  | 9,865 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | 11,026 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | 9,865 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Charge- offs |  |  |  |  |  |  |  |  | (29)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | (19)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Recoveries |  |  |  |  |  |  |  |  | 49 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | 12 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Net charge- offs |  |  |  |  |  |  |  |  | 20 us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | (7)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | (1,430)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | 1,168 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Balance at end of period | 9,616 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |  |  |  | 11,026 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |  |  |  | 9,616 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember | 11,026 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Residential Real Estate Permanent Mortgage [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 2,825 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |  |  |  | 2,781 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | 2,825 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | 2,781 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Charge- offs |  |  |  |  |  |  |  |  | (207)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | (162)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Recoveries |  |  |  |  |  |  |  |  | 78 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | 32 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Net charge- offs |  |  |  |  |  |  |  |  | (129)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | (130)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | 252 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | 174 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Balance at end of period | 2,948 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |  |  |  | 2,825 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |  |  |  | 2,948 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember | 2,825 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Residential Real Estate All Other [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 6,708 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |  |  |  | 7,034 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | 6,708 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | 7,034 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Charge- offs |  |  |  |  |  |  |  |  | (171)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | (209)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Recoveries |  |  |  |  |  |  |  |  | 32 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | 33 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Net charge- offs |  |  |  |  |  |  |  |  | (139)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | (176)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | (300)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | (150)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Balance at end of period | 6,269 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |  |  |  | 6,708 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |  |  |  | 6,269 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember | 6,708 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Non-consumer Non-real Estate [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 8,977 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |  |  |  | 9,385 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | 8,977 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | 9,385 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Charge- offs |  |  |  |  |  |  |  |  | (564)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | (217)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Recoveries |  |  |  |  |  |  |  |  | 70 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | 175 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Net charge- offs |  |  |  |  |  |  |  |  | (494)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | (42)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | 4,288 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | (366)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Balance at end of period | 12,771 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |  |  |  | 8,977 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |  |  |  | 12,771 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember | 8,977 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Consumer Non-real Estate [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 2,556 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |  |  |  | 2,451 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | 2,556 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | 2,451 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Charge- offs |  |  |  |  |  |  |  |  | (687)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | (597)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Recoveries |  |  |  |  |  |  |  |  | 203 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | 225 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Net charge- offs |  |  |  |  |  |  |  |  | (484)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | (372)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | 332 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | 477 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Balance at end of period | 2,404 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |  |  |  | 2,556 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |  |  |  | 2,404 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember | 2,556 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Other Loans [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 1,991 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |  |  |  | 1,885 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | 1,991 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | 1,885 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Charge- offs |  |  |  |  |  |  |  |  | (351)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | (300)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Recoveries |  |  |  |  |  |  |  |  | 149 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | 75 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Net charge- offs |  |  |  |  |  |  |  |  | (202)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | (225)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | 570 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | 331 us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Balance at end of period | 2,359 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |  |  |  | 1,991 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |  |  |  | 2,359 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember | 1,991 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Acquired Loans [Member] |  |  |  |  |  |  |  |  |  |  |
Financing Receivable, Allowance for Credit Losses [Line Items] |  |  |  |  |  |  |  |  |  |  |
Balance at beginning of period |  |  |  | 124 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |  |  |  | 220 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | 124 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | 220 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Charge- offs |  |  |  |  |  |  |  |  | (568)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | (53)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Recoveries |  |  |  |  |  |  |  |  | 719 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | 39 us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Net charge- offs |  |  |  |  |  |  |  |  | 151 us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | (14)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Provisions charged to operations |  |  |  |  |  |  |  |  | (159)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | (82)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Balance at end of period | $ 116 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |  |  |  | $ 124 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |  |  |  | $ 116 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember | $ 124 us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |

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- Definition Amount of other addition (reduction) in allowance reserve for credit loss. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-03.7(d)) -URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 7 -Subparagraph d -Article 9 + Details
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Namespace Prefix: | us-gaap_
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