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Derivative Financial Instruments - Summary of Company's Net Credit Exposure Relating to Oil and Gas Swaps and Options with Bank Counterparties (Detail) $ in Thousands | Dec. 31, 2022 USD ($)
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Oil and Natural Gas Swaps and Options [Member] |
Credit Derivatives [Line Items] |
Credit exposure | $ 6,560

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_CreditDerivativesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Fair value of credit risk derivative asset after deduction of credit risk derivative liability. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 4K -Subparagraph (c) -SubTopic 10 -Topic 815 -Publisher FASB -URI https://asc.fasb.org//1943274/2147480434/815-10-50-4K + Details
Name: | us-gaap_CreditRiskDerivativesAtFairValueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=banf_OilAndNaturalGasSwapsAndOptionsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |