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Retirement Plans - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014 Plans
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Number of retirement plans	2banf_NumberOfRetirementPlans
Maximum [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Maximum legal limit of employer contribution to plan	3.00%us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch / us-gaap_RangeAxis = us-gaap_MaximumMember

X

- Details

Name:	banf_DefinedBenefitPlansAndOtherPostretirementBenefitPlansLineItems
Namespace Prefix:	banf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Number of retirement plans.

+ References

No definition available.

+ Details

Name:	banf_NumberOfRetirementPlans
Namespace Prefix:	banf_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Percentage employer matches of the employee's percentage contribution matched.

+ References

No definition available.

+ Details

Name:	us-gaap_DefinedContributionPlanEmployerMatchingContributionPercentOfMatch
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: