| Document and Entity Information | Nov. 15, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Nov. 15, 2021 |
| Entity Registrant Name | HALLMARK FINANCIAL SERVICES, INC. |
| Entity Central Index Key | 0000819913 |
| Entity Incorporation, State or Country Code | NV |
| Entity File Number | 001-11252 |
| Entity Tax Identification Number | 87-0447375 |
| Entity Address, Address Line One | 5420 Lyndon B. Johnson Freeway |
| Entity Address, Adress Line Two | 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock $0.18 par value |
| Trading Symbol | HALL |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
