Financing receivable modifications due to impact of CARES act.

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- Definition

Nonaccrual loan amount guaranteed by government agencies.

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No definition available.

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- Definition

Paycheck protection program loan.

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No definition available.

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- Definition

Paycheck protection program unamortized processing fees.

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No definition available.

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- Definition

Paycheck protection program unamortized processing fees included in interest income.

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- Definition

Percentage of loans secured by real estate.

+ References

No definition available.

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- Definition

Amount of credit loss expense (reversal of expense) for financing receivable from change in methodology.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 11
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=119407570&loc=SL82919244-210447

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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.

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No definition available.

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- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 40
-Section 50
-Paragraph 1
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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

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- Definition

Amount of credit loss expense (reversal of expense) for financing receivable.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 50
-Paragraph 13
-Subparagraph (b)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
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Loans Held for Investment and Allowance for Credit Losses on Loans - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	$ 6,674,954,000		$ 6,674,954,000		$ 5,662,143,000
Paycheck protection program loan	825,100,000		825,100,000
Paycheck protection program unamortized processing fees	26,200,000		26,200,000
Paycheck protection program unamortized processing fees included in interest income	3,600,000		3,600,000
Interest income that would have been recognized			983,000	$ 1,000,000.0
Decrease in allowance for credit losses upon adoption of ASC 326			3,195,000
Provision for credit losses on loans	19,333,000	$ 2,433,000	38,916,000	$ 4,117,000
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Loans modification	$ 939,800,000		939,800,000
U.S. Federal Agencies [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual loans guaranteed by government agencies			$ 8,000,000.0
BancFirst’s [Member]
Financing Receivable Recorded Investment [Line Items]
Percentage of loans secured by real estate	50.00%		50.00%
BancFirst’s [Member] \| Commercial and Agricultural Non-Real Estate [Member] \| Ancillary Services [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	$ 78,000,000		$ 78,000,000		90,000,000
BancFirst’s [Member] \| Energy [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	229,000,000		229,000,000		189,000,000
BancFirst’s [Member] \| Energy [Member] \| Midstream Energy Loans
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	45,000,000		45,000,000		41,000,000
Pegasus Bank [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	484,804,000		484,804,000		430,705,000
Decrease in allowance for credit losses upon adoption of ASC 326			(2,488,000)
Provision for credit losses on loans	(53,000)		587,000
Pegasus Bank [Member] \| Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	$ 246,000,000		$ 246,000,000
Percentage of loans secured by real estate	51.00%		51.00%
Pegasus Bank [Member] \| Commercial and Agricultural Non-Real Estate [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	$ 208,000,000		$ 208,000,000		172,000,000
Pegasus Bank [Member] \| Energy [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	88,000,000		88,000,000		57,000,000
Pegasus Bank [Member] \| Energy [Member] \| Ancillary Services [Member]
Financing Receivable Recorded Investment [Line Items]
Loans (net of unearned interest)	$ 8,000,000		$ 8,000,000		$ 7,000,000