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Loans and Allowance for Loan Losses - Internal Loan Grading by Class of Loans (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 3,860,831us-gaap_LoansAndLeasesReceivableGrossCarryingAmount	$ 3,387,146us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	483,635us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember	455,032us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember
Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	954,003us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember	863,382us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember
Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	307,579us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember	265,980us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember
Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	637,088us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember	567,873us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember
Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	966,707us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember	795,315us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember
Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	247,765us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember	228,335us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember
Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	162,417us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember	145,356us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember
Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	101,637us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember	65,873us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember
Grade 1 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	3,258,055us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	2,898,156us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	402,706us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	382,798us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	795,209us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	711,081us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	272,411us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	233,924us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	529,555us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	475,421us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	821,094us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	691,772us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	233,424us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	214,153us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	157,191us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	141,787us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 1 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	46,465us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember	47,220us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeOneMember
Grade 2 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	507,064us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	423,378us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	75,555us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	66,139us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	133,542us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	125,617us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	27,855us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	24,882us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	99,214us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	82,571us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	117,457us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	97,812us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	12,229us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	11,819us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	4,261us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	2,558us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 2 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	36,951us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember	11,980us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeTwoMember
Grade 3 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	78,999us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	51,005us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,008us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	5,446us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	20,126us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	20,309us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	6,369us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	6,081us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	6,146us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	8,238us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	26,550us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	4,462us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,548us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	1,931us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	601us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	772us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 3 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	12,651us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember	3,766us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeThreeMember
Grade 4 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	16,158us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	14,606us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Non-residential Real Estate Owner Occupied [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	366us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	649us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOwnerOccupiedMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Non-residential Real Estate Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,126us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	6,375us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonResidentialRealEstateOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Residential Real Estate Permanent Mortgage [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	944us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	1,093us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstatePermanentMortgageMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Residential Real Estate All Other [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	2,173us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	1,643us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ResidentialRealEstateAllOtherMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Non-consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	1,606us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	1,269us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_NonConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	564us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	431us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	173us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	239us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 4 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	5,206us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember	2,907us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFourMember
Grade 5 [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	555us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeFiveMember	1us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_InternalCreditAssessmentAxis = banf_GradeFiveMember
Grade 5 [Member] | Consumer Non-real Estate [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans		1us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_ConsumerNonRealEstateMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFiveMember
Grade 5 [Member] | Other Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	191us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_OtherLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFiveMember
Grade 5 [Member] | Acquired Loans [Member]
Financing Receivable, Allowance for Credit Losses [Line Items]
Total loans	$ 364us-gaap_LoansAndLeasesReceivableGrossCarryingAmount / us-gaap_FinancialInstrumentAxis = banf_AcquiredLoansMember / us-gaap_InternalCreditAssessmentAxis = banf_GradeFiveMember

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- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. 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 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=28367877&loc=d3e4428-111522

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