Fair Value Measurements - Additional Information (Detail) (USD $)	6 Months Ended
Jun. 30, 2013
Fair Value Disclosures [Abstract]
Loan held for sale selling period	30 days
Amount of non-financial assets (liabilities)	$ 0
Non-financial assets or liabilities for which no impairment was provided	$ 0

Non Financial Assets Liabilities For Which No Impairment Provided

No definition available.

Name:	banf_NonFinancialAssetsLiabilitiesForWhichNoImpairmentProvided
Namespace Prefix:	banf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration