XML 62 R49.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2019
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Days from origination after which mortgage loan are sold | 30 days |
Loan upon which a default of principal or interest has existed for a period | 90 days |
Intangible assets, Estimated useful lives | 6 years 8 months 12 days |
Accounting Standards Update 2016-01 [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Additional income from changes in equity investments | $ 48,900 |
Accounting Standards Update 2016-01 [Member] | Other Assets [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Effect of change in accounting principle | 5,700,000 |
Accounting Standards Update 2016-01 [Member] | Equity Securities [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Effect of change in accounting principle | (5,700,000) |
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Effect of change in accounting principle | 618,000 |
Accounting Standards Update 2016-01 [Member] | Accumulated Other Comprehensive Income [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Effect of change in accounting principle | $ 618,000 |
Accounting Standards Update 2016-02 [Member] | Scenario Forecast [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Effect of change in accounting principle |  | $ 3,000,000
Core Deposit Intangibles [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Intangible assets, Estimated useful lives | 6 years 10 months 24 days |
Minimum [Member] | Core Deposit Intangibles [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Intangible assets, Estimated useful lives | 7 years |
Minimum [Member] | Customer Relationship Intangibles [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Intangible assets, Estimated useful lives | 3 years |
Maximum [Member] | Core Deposit Intangibles [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Intangible assets, Estimated useful lives | 10 years |
Maximum [Member] | Customer Relationship Intangibles [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Intangible assets, Estimated useful lives | 18 years |
Home Equity Lines of Credit [Member] | Maximum [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Loans and finance receivables portfolio percentage | 9.00% |
First Liens [Member] | Minimum [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Loans and finance receivables portfolio percentage | 82.00% |
Junior Liens [Member] | Maximum [Member] |  |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |  |
Loans and finance receivables portfolio percentage | 9.00% |

X
- Definition Basis of presentation and summary of significant accounting policies. + References No definition available. + Details
Name: | banf_BasisOfPresentationAndSummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix: | banf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loans and finance receivables portfolio percentage. + References No definition available. + Details
Name: | banf_LoansAndFinanceReceivablesPortfolioPercentage
Namespace Prefix: | banf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Period for sale of mortgage loan from origination. + References No definition available. + Details
Name: | banf_PeriodForSaleOfMortgageLoanFromOrigination
Namespace Prefix: | banf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Period of default of principal or interest upon loan. + References No definition available. + Details
Name: | banf_PeriodOfDefaultOfPrincipalOrInterestUponLoan
Namespace Prefix: | banf_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of cumulative effect of the change in accounting principle or new accounting pronouncement on retained earnings or other components of equity or net assets in the statement of financial position as of the beginning of the earliest period presented. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22580-107794 + Details
Name: | us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleCumulativeEffectOfChangeOnEquityOrNetAssets1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of the effect of a change in accounting principle on net income. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b)(2) -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22499-107794 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22580-107794 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 250 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109234566&loc=d3e22583-107794 + Details
Name: | us-gaap_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfChangeOnNetIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BalanceSheetLocationAxis=us-gaap_OtherAssetsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_RetainedEarningsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementScenarioAxis=us-gaap_ScenarioForecastMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CoreDepositsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis=us-gaap_CustomerRelationshipsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LienCategoryAxis=us-gaap_SeniorLienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LienCategoryAxis=us-gaap_JuniorLienMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |