Line of Credit - Additional Information (Detail)	Dec. 31, 2022 USD ($) Institution
Debt Instrument [Line Items]
Maximum drawing capacity	$ 741,800,000
FHLB stock holdings	655,500
Advances outstanding	$ 0
Number of financial institution \| Institution	2
Pegasus [Member]
Debt Instrument [Line Items]
Advances outstanding	$ 0
Worthington [Member]
Debt Instrument [Line Items]
Maximum drawing capacity	5,500,000
Advances outstanding	0
Residential Mortgage [Member]
Debt Instrument [Line Items]
Line of credit assets pledged as collateral	938,800,000
Revolving Line of Credit Member] \| BancFirst [Member]
Debt Instrument [Line Items]
Maximum drawing capacity	25,000,000.0
Revolving Line of Credit Member] \| Pegasus [Member]
Debt Instrument [Line Items]
Maximum drawing capacity	20,000,000.0
Revolving Line of Credit Member] \| Worthington [Member]
Debt Instrument [Line Items]
Maximum drawing capacity	$ 3,000,000.0

Line of credit residential first mortgages pledged as collateral.

No definition available.

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Namespace Prefix:	banf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Number of financial institution.

+ References

No definition available.

+ Details

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Federal Home Loan Bank (FHLB) stock represents an equity interest in a FHLB. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 325
-Section 45
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=123599499&loc=d3e63345-112809

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the amount outstanding under the credit facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=123594938&loc=d3e13433-108611

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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Namespace Prefix:
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Balance Type:
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- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageMember
Namespace Prefix:
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Balance Type:
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- Details

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- Details

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