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Loans Held for Investment and Allowance for Credit Losses on Loans - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024
Financing Receivable Recorded Investment [Line Items]
Gains (losses) on sale of property held in other real estate owned	$ 25,000	$ 177,000
Interest income recognized on nonaccrual loans	0	0
Interest income that would have been recognized	1,000,000	$ 696,000
Balance of modifies loans	1,900,000		$ 14,800,000
Commercial Real Estate
Financing Receivable Recorded Investment [Line Items]
Other real estate	29,500,000		28,100,000
U.S. Federal Agencies [Member]
Financing Receivable Recorded Investment [Line Items]
Nonaccrual loans guaranteed by government agencies	$ 9,200,000		$ 9,000,000
Parent Company [Member]
Financing Receivable Recorded Investment [Line Items]
Percentage of loans secured by real estate	71.00%
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%

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Percentage of loans secured by real estate.

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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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