| Document And Entity Information | Oct. 19, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Oct. 19, 2023 |
| Entity Registrant Name | BancFirst Corporation |
| Entity Central Index Key | 0000760498 |
| Entity Emerging Growth Company | false |
| Securities Act File Number | 0-14384 |
| Entity Incorporation, State or Country Code | OK |
| Entity Tax Identification Number | 73-1221379 |
| Entity Address, Address Line One | 100 N. Broadway Ave. |
| Entity Address, City or Town | Oklahoma City |
| Entity Address, State or Province | OK |
| Entity Address, Postal Zip Code | 73102-8405 |
| City Area Code | 405 |
| Local Phone Number | 270-1086 |
| Entity Information, Former Legal or Registered Name | Not Applicable |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $1.00 Par Value Per Share |
| Trading Symbol | BANF |
| Security Exchange Name | NASDAQ |
