Loans Held for Investment and Allowance for Credit Losses on Loans - Additional Information (Detail) - USD ($)	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Financing Receivable Recorded Investment [Line Items]
Gains (losses) on sale of property held in other real estate owned	$ 1,500,000	$ 728,000	$ 4,200,000
Write down of property held in other real estate owned	4,000,000	5,200,000	3,700,000
Balance of modifies loans	14,800,000	5,300,000
Interest income recognized on nonaccrual loans	0	0	0
Interest income that would have been recognized	3,500,000	1,600,000	$ 1,300,000
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Other real estate	28,100,000	29,400,000
U.S. Federal Agencies [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual loans guaranteed by government agencies	$ 9,000,000	$ 6,700,000
BancFirst [Member]
Financing Receivable Recorded Investment [Line Items]
Loan percentage	83.00%
Pegasus and Worthington [Member]
Financing Receivable Recorded Investment [Line Items]
Loan percentage	17.00%
Parent Company [Member]
Financing Receivable Recorded Investment [Line Items]
Percentage of loans secured by real estate	69.00%

Financing receivable amount of loans modified.

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Financing receivable impaired interest on nonaccrual loans.

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Loan percentage.

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Nonaccrual loans amount guaranteed by government agencies.

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Percentage of loans secured by real estate.

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Write down of other real estate.

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Amount of interest income on financing receivable on nonaccrual status.

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The net gain (loss) resulting from sales and other disposals of other real estate owned, increases (decreases) in the valuation allowance for foreclosed real estate, and write-downs of other real estate owned after acquisition or physical possession.

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Carrying amount of other real estate not separately disclosed, including, but not limited to, real estate investments, real estate loans that qualify as investments in real estate, and premises that are no longer used in operations may also be included in real estate owned. This does not include real estate assets taken in settlement of troubled loans through surrender or foreclosure.

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