| Cover - USD ($) $ in Millions | 12 Months Ended | ||
| Dec. 31, 2022 | Apr. 26, 2023 | Jun. 30, 2022 | |
| Document Information [Line Items] | |||
| Document Type | 10-K/A | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Document Financial Statement Error Correction [Flag] | false | ||
| Entity Interactive Data Current | Yes | ||
| ICFR Auditor Attestation Flag | false | ||
| Amendment Flag | true | ||
| Amendment Description | This Amendment No. 2 to the Annual Report on Form 10-K of Business First Bancshares, Inc. (the “Company”) for the year ended December 31, 2022 as filed with the Securities and Exchange Commission (the “SEC”) on March 2, 2023 (as previously amended by that certain Amendment No. 1 filed with the SEC on March 15, 2023, the “Original Form 10-K”), is being filed for the purpose of amending and restating Part III (Items 10-14) to provide certain additional information required therein. This information was previously omitted from the Original Form 10-K in reliance on General Instruction G(3) to Form 10-K. | ||
| Document Period End Date | Dec. 31, 2022 | ||
| Document Fiscal Year Focus | 2022 | ||
| Document Fiscal Period Focus | FY | ||
| Entity Information [Line Items] | |||
| Entity Registrant Name | BUSINESS FIRST BANCSHARES, INC. | ||
| Entity Central Index Key | 0001624322 | ||
| Entity File Number | 001-38447 | ||
| Entity Tax Identification Number | 20-5340628 | ||
| Entity Incorporation, State or Country Code | LA | ||
| Current Fiscal Year End Date | --12-31 | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Shell Company | false | ||
| Entity Filer Category | Accelerated Filer | ||
| Entity Small Business | false | ||
| Entity Emerging Growth Company | false | ||
| Entity Public Float | $ 449.8 | ||
| Entity Contact Personnel [Line Items] | |||
| Entity Address, Address Line One | 500 Laurel Street, Suite 101 | ||
| Entity Address, City or Town | Baton Rouge | ||
| Entity Address, State or Province | LA | ||
| Entity Address, Postal Zip Code | 70801 | ||
| Entity Phone Fax Numbers [Line Items] | |||
| City Area Code | 225 | ||
| Local Phone Number | 248-7600 | ||
| Entity Listings [Line Items] | |||
| Title of 12(b) Security | Common Stock, par value $1.00 per share | ||
| Trading Symbol | BFST | ||
| Security Exchange Name | NASDAQ | ||
| Entity Common Stock, Shares Outstanding | 25,319,520 |
| Audit Information | 12 Months Ended |
| Dec. 31, 2022 | |
| Auditor [Table] | |
| Auditor Name | FORVIS, LLP |
| Auditor Firm ID | 686 |
| Auditor Location | Fort Worth, Texas |
| Pay vs Performance Disclosure | 12 Months Ended | ||
| Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | |
| Pay vs Performance Disclosure [Table] | |||
| Pay vs Performance [Table Text Block] | Pay versus Performance In accordance with rules adopted by the SEC pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010, we provide the following disclosure regarding executive “compensation actually paid” (“CAP”) and certain Company performance for the fiscal years listed below. CAP is calculated pursuant to SEC rules, which require various adjustments be made to amounts that have been previously reported in the Summary Compensation Table in previous years; the dollar amounts do not reflect the actual amount of compensation earned or received by our CEO or other NEOs during the applicable year. Year-end value of $100 invested on 12/31/2019 in: Year CEO Summary Compensation Table Total (1) $ CEO Compensation Actually Paid (1,2) $ Average Summary Compensation Table Total for Non-CEO NEOs (1) $ Average Compensation Actually Paid to Non-CEO NEOs (1,2) $ BFST (3) $ Peer Group (3) $ Net Income (in millions) $ Core ROA (4) 2022 2,521,035 2,034,441 924,152 743,868 94.63 106.02 54.3 1.05 2021 2,025,480 2,180,523 898,880 878,009 118.62 117.08 52.1 1.22 2020 1,744,682 1,320,084 753,828 590,899 83.70 87.90 30.0 1.09 Footnotes (1) David R. Melville III has served as our President and CEO since 2011. The information presented for Non-CEO NEOs reflects the average Summary Compensation Table total compensation and average CAP for the following executives by year: 2022: Gregory Robertson, Philip Jordan , Keith Mansfield, Saundra Strong 2021: Gregory Robertson, Philip Jordan, Keith Mansfield, Mark Folse 2020: Gregory Robertson, Philip Jordan (2) Deductions from, and additions to, total compensation in the Summary Compensation Table by year to calculate CAP include: | ||
| PEO Total Compensation Amount | $ 2,521,035 | $ 2,025,480 | $ 1,744,682 |
| PEO Actually Paid Compensation Amount | $ 2,034,441 | 2,180,523 | 1,320,084 |
| Adjustment To PEO Compensation, Footnote [Text Block] | 2022 2021 2020 CEO David R. Melville III Average Non- CEO NEOs CEO David R. Melville III Average Non- CEO NEOs CEO David R. Melville III Average Non- CEO NEOs Total Compensation from Summary Compensation Table $ 2,521,035 924,152 2,025,480 898,880 1,744,682 753,828 Adjustments for Equity Awards Adjustment for grant date values in the Summary Compensation Table $ (945,122 ) $ (314,169 ) $ (676,478 ) $ (261,427 ) $ (578,164 ) $ (222,853 ) Year-end fair value of unvested awards granted in the current year $ 363,760 $ 106,161 $ 537,550 $ 155,401 $ 185,968 $ 74,701 Year-over-year difference of year-end fair values for unvested awards granted in prior years $ (60,863 ) $ (17,595 ) $ 34,938 $ 10,528 $ (16,383 ) $ (6,641 ) Fair values at vest date for awards granted and vested in current year $ 199,847 $ 58,307 $ 227,167 $ 65,670 $ 61,655 $ 24,759 Difference in fair values between prior year-end fair values and vest date fair values for awards granted in prior years $ (59,333 ) $ (17,389 ) $ 26,212 $ 7,309 $ (82,617 ) $ (34,900 ) Forfeitures during current year equal to prior year-end fair value $ - $ - $ - $ - $ - $ - Dividends or dividend equivalents not otherwise included in total compensation $ 15,117 $ 4,401 $ 5,653 $ 1,648 $ 4,943 $ 2,004 Total Adjustments for Equity Awards $ (486,594 ) $ (180,284 ) $ 155,043 $ (20,871 ) $ (424,598 ) $ (162,929 ) Compensation Actually Paid (as calculated) $ 2,034,441 $ 743,868 $ 2,180,523 $ 878,009 $ 1,320,084 $ 590,899 (3) TSR is calculated by dividing the sum of the cumulative amount of dividends for the measurement period, assuming dividend reinvestment, and the difference between the Company’s share price at the end and the beginning of the measurement period by the Company’s share price at the beginning of the measurement period. TSR is determined based on the value of an initial fixed investment of $100. The TSR peer group consists of the KBW Nasdaq Regional Bank Index. (4) Core ROA is a non-GAAP financial measure. | ||
| Non-PEO NEO Average Total Compensation Amount | $ 924,152 | 898,880 | 753,828 |
| Non-PEO NEO Average Compensation Actually Paid Amount | $ 743,868 | 878,009 | 590,899 |
| Compensation Actually Paid vs. Total Shareholder Return [Text Block] | Pay Versus Performance: Graphical Description The illustrations below provide a graphical description of CAP (as calculated in accordance with the SEC rules) and the following measures: ● the Company’s cumulative TSR and the Peer Group’s cumulative TSR; ● the Company’s Net Income; and ● the Company Selected Measure, which for BFST is Core ROA. CAP and Cumulative TSR / Cumulative TSR of the Peer Group | ||
| Compensation Actually Paid vs. Net Income [Text Block] | CAP and Company Net Income | ||
| Tabular List [Table Text Block] | Tabular List of Financial Performance Measures In our assessment, the most important financial performance measures used to link CAP (as calculated in accordance with the SEC rules), to our NEOs in 2022 to our performance were: ● Net Income ● Core ROA ● Core Efficiency Ratio ● Classified Assets Coverage Ratio ● Percentage Asset Growth (Organic) | ||
| Total Shareholder Return Amount | $ 94.63 | 118.62 | 83.70 |
| Peer Group Total Shareholder Return Amount | 106.02 | 117.08 | 87.90 |
| Net Income (Loss) | $ 54,300,000 | $ 52,100,000 | $ 30,000,000 |
| Company Selected Measure Amount | 1.05 | 1.22 | 1.09 |
| Measure [Axis]: 1 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Net Income | ||
| Measure [Axis]: 2 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Core ROA | ||
| Measure [Axis]: 3 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Core Efficiency Ratio | ||
| Measure [Axis]: 4 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Classified Assets Coverage Ratio | ||
| Measure [Axis]: 5 | |||
| Pay vs Performance Disclosure [Table] | |||
| Measure Name | Percentage Asset Growth (Organic) | ||
| PEO Adjustment for grant date values in the Summary Compensation [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ (945,122) | $ (676,478) | $ (578,164) |
| NEO Adjustment for grant date values in the Summary Compensation [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (314,169) | (261,427) | (222,853) |
| PEO Year-end fair value of unvested awards granted in the current year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 363,760 | 537,550 | 185,968 |
| NEO Year-end fair value of unvested awards granted in the current year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 106,161 | 155,401 | 74,701 |
| PEO Year-over-year difference of year-end fair values for unvested awards granted in prior years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (60,863) | 34,938 | (16,383) |
| NEO Year-over-year difference of year-end fair values for unvested awards granted in prior years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (17,595) | 10,528 | (6,641) |
| PEO Fair values at vest date for awards granted and vested in current year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 199,847 | 227,167 | 61,655 |
| NEO Fair values at vest date for awards granted and vested in current year [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 58,307 | 65,670 | 24,759 |
| PEO Difference in fair values between prior year-end fair values and vest date fair values for awards granted in prior years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (59,333) | 26,212 | (82,617) |
| NEO Difference in fair values between prior year-end fair values and vest date fair values for awards granted in prior years [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (17,389) | 7,309 | (34,900) |
| PEO Forfeitures during current year equal to prior year-end fair value [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| NEO Forfeitures during current year equal to prior year-end fair value [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 0 | 0 | 0 |
| PEO Dividends or dividend equivalents not otherwise included in total compensation [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 15,117 | 5,653 | 4,943 |
| NEO Dividends or dividend equivalents not otherwise included in total compensation [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | 4,401 | 1,648 | 2,004 |
| PEO Adjustments for Equity Awards [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | (486,594) | 155,043 | (424,598) |
| NEO Adjustments for Equity Awards [Member] | |||
| Pay vs Performance Disclosure [Table] | |||
| Adjustment to Compensation Amount | $ (180,284) | $ (20,871) | $ (162,929) |
