Stock-Based Compensation - Summary of Accumulated Stock Units (Detail) - $ / shares	Dec. 31, 2021	Dec. 31, 2020
Share-based Payment Arrangement [Abstract]
Accumulated stock units	152,754	148,278
Average price	$ 30.86	$ 28.57

Deferred compensation arrangement with individual accumulated stock units For deferred board fees.

No definition available.

Name:	banf_DeferredCompensationArrangementWithIndividualAccumulatedStockUnitsForDeferredBoardFees
Namespace Prefix:	banf_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant