| Document And Entity Information | Oct. 26, 2021 |
| Document Information [Line Items] | |
| Entity, Registrant Name | HARTE HANKS, INC. |
| Document, Type | 8-K |
| Document, Period End Date | Oct. 26, 2021 |
| Entity, Incorporation, State or Country Code | DE |
| Entity, File Number | 1-7120 |
| Entity, Tax Identification Number | 74-1677284 |
| Entity, Address, Address Line One | 2800 Wells Branch Parkway |
| Entity, Address, City or Town | Austin |
| Entity, Address, State or Province | TX |
| Entity, Address, Postal Zip Code | 78728 |
| City Area Code | 512 |
| Local Phone Number | 434-1100 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | HRTH |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0000045919 |
