Derivative Financial Instruments - Summary of Company's Recognized Income Related to Activity Included in Other Noninterest Income (Detail) - Oil and Natural Gas Swaps and Options [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative Instruments, Gain (Loss) [Line Items]
Derivative income	$ 78	$ 82	$ 374	$ 279
Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Noninterest Income, Other	Noninterest Income, Other	Noninterest Income, Other	Noninterest Income, Other

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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BANCFIRST CORP /OK/ 10-Q