Loans and Allowance for Loan Losses - Activity in All by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified
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3 Months Ended |
Mar. 31, 2015
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Mar. 31, 2014
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
$ 40,889us-gaap_LoansAndLeasesReceivableAllowance |
$ 39,034us-gaap_LoansAndLeasesReceivableAllowance |
Charge- offs |
(762)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs |
(474)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs |
Recoveries |
96us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery |
146us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery |
Net charge- offs |
(666)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet |
(328)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet |
Provisions charged to operations |
1,334us-gaap_ProvisionForLoanAndLeaseLosses |
1,218us-gaap_ProvisionForLoanAndLeaseLosses |
Balance at end of period |
41,557us-gaap_LoansAndLeasesReceivableAllowance |
39,924us-gaap_LoansAndLeasesReceivableAllowance |
Non-residential Real Estate Owner Occupied [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
4,406us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
4,827us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Charge- offs |
(1)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
(4)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Recoveries |
1us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
31us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Net charge- offs |
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27us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Provisions charged to operations |
55us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
158us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Balance at end of period |
4,461us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
5,012us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember |
Non-residential Real Estate Other [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
9,616us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
11,026us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Recoveries |
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3us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Net charge- offs |
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3us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Provisions charged to operations |
282us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
(344)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Balance at end of period |
9,898us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
10,685us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember |
Residential Real Estate Permanent Mortgage [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
2,948us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
2,825us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Charge- offs |
(40)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
(130)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Recoveries |
9us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
10us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Net charge- offs |
(31)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
(120)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Provisions charged to operations |
67us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
532us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Balance at end of period |
2,984us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
3,237us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember |
Residential Real Estate All Other [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
6,269us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
6,708us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Charge- offs |
(68)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
(49)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Recoveries |
5us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
4us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Net charge- offs |
(63)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
(45)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Provisions charged to operations |
372us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
(178)us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Balance at end of period |
6,578us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
6,485us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember |
Non-consumer Non-real Estate [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
12,771us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
8,977us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Charge- offs |
(153)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
(70)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Recoveries |
31us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
14us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Net charge- offs |
(122)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
(56)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Provisions charged to operations |
419us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
782us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Balance at end of period |
13,068us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
9,703us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember |
Consumer Non-real Estate [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
2,404us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
2,556us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Charge- offs |
(127)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
(140)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Recoveries |
15us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
62us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Net charge- offs |
(112)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
(78)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Provisions charged to operations |
35us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
95us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Balance at end of period |
2,327us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
2,573us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember |
Other Loans [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
2,359us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
1,991us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Charge- offs |
(213)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
(64)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Recoveries |
9us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
17us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Net charge- offs |
(204)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
(47)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Provisions charged to operations |
86us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
128us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Balance at end of period |
2,241us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
2,072us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember |
Acquired Loans [Member] |
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Financing Receivable, Allowance for Credit Losses [Line Items] |
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Balance at beginning of period |
116us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
124us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Charge- offs |
(160)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
(17)us-gaap_FinancingReceivableAllowanceForCreditLossesWriteOffs / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Recoveries |
26us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
5us-gaap_FinancingReceivableAllowanceForCreditLossesRecovery / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Net charge- offs |
(134)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
(12)us-gaap_AllowanceForLoanAndLeaseLossesAdjustmentsNet / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Provisions charged to operations |
18us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
45us-gaap_ProvisionForLoanAndLeaseLosses / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |
Balance at end of period |
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$ 157us-gaap_LoansAndLeasesReceivableAllowance / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember |