XML 65 R52.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Description of Business and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 USD ($)
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 | 5 years 10 months 24 days
Excess tax benefit from share-based compensation | $ 2,601
Accounting Standards Update 2016-09 [Member] |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |
Excess tax benefit from share-based compensation | $ 2,600
Core Deposit Intangibles [Member] |
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items] |
Intangible assets, Estimated useful lives | 6 years
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 | 8.00%
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 | 10.00%

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 Amount of cash outflow for realized tax benefit related to deductible compensation cost reported on the entity's tax return for equity instruments in excess of the compensation cost for those instruments recognized for financial reporting purposes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 20 -Section 55 -Paragraph 24 -URI http://asc.fasb.org/extlink&oid=96864182&loc=d3e11374-113907 + Details
Name: | us-gaap_ExcessTaxBenefitFromShareBasedCompensationOperatingActivities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201609Member
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: | us-gaap_RangeAxis=us-gaap_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: | us-gaap_RangeAxis=us-gaap_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: |