| Document and Entity Information - USD ($) $ in Millions | 12 Months Ended | | |
| Dec. 31, 2022 | Apr. 13, 2023 | Jun. 30, 2022 |
| Cover [Abstract] | | | |
| Document Type | 10-K/A | | |
| Document Annual Report | true | | |
| Document Transition Report | false | | |
| Document Period End Date | Dec. 31, 2022 | | |
| Entity File Number | 001-11252 | | |
| Entity Registrant Name | Hallmark Financial Services, Inc. | | |
| Entity Incorporation, State or Country Code | NV | | |
| Entity Tax Identification Number | 87-0447375 | | |
| Entity Address, Address Line One | 5420 Lyndon B. Johnson Freeway, Suite 1100 | | |
| Entity Address, City or Town | Dallas | | |
| Entity Address, State or Province | TX | | |
| Entity Address, Postal Zip Code | 75240 | | |
| City Area Code | 817 | | |
| Local Phone Number | 348-1600 | | |
| Title of 12(b) Security | Common Stock, $1.00 par value | | |
| Trading Symbol | HALL | | |
| Security Exchange Name | NASDAQ | | |
| Entity Well-known Seasoned Issuer | No | | |
| Entity Voluntary Filers | No | | |
| Entity Current Reporting Status | Yes | | |
| Entity Interactive Data Current | Yes | | |
| Entity Filer Category | Non-accelerated Filer | | |
| Entity Small Business | true | | |
| Entity Emerging Growth Company | false | | |
| ICFR Auditor Attestation Flag | false | | |
| Entity Shell Company | false | | |
| Entity Public Float | | | $ 31.6 |
| Entity Common Stock, Shares Outstanding | | 1,818,482 | |
| Entity Central Index Key | 0000819913 | | |
| Current Fiscal Year End Date | --12-31 | | |
| Document Fiscal Year Focus | 2022 | | |
| Document Fiscal Period Focus | FY | | |
| Amendment Flag | true | | |
| Amendment Description | This Amendment No. 1 (this “Amendment”) on Form 10-K/A is filed with respect to Hallmark Financial Services, Inc.’s Annual Report on Form 10-K for the fiscal year ended December 31, 2022 (the “Form 10-K”), filed with the Securities and Exchange Commission (the “SEC”) on March 28, 2023. This Amendment updates the Form 10- K, which omitted Part III (Items 10, 11, 12, 13 and 14) in reliance on General Instruction G(3) to Form 10-K, which provides that such information may be either incorporated by reference from the registrant’s definitive proxy statement or included in an amendment to Form 10-K, in either case filed with the SEC not later than 120 days after the end of the fiscal year. While we intend to file our preliminary proxy statement for our 2023 annual meeting of shareholders shortly, the timing of the filing of a definitive proxy statement will be outside this window for incorporation by reference. | | |
| Auditor Name | Baker Tilly US, LLP | | |
| Auditor Firm ID | 23 | | |
| Auditor Location | Madison, Wisconsin | | |
