Long-Term Debt	12 Months Ended
Dec. 31, 2017
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt As of December 31, 2017 the Texas Capital Facility was outstanding, but at each of of years ended December 31, 2017 and 2016, we had no debt outstanding. Credit Facilities On March 10, 2016, we entered into a secured credit facility with Wells Fargo Bank, N.A. as Administrative Agent, consisting of a maximum $65.0 million revolving credit facility (the "2016 Revolving Credit Facility"), and a $45.0 million term loan facility (the "2016 Term Loan", and together with the 2016 Revolving Credit Facility, the "2016 Secured Credit Facility"). The 2016 Secured Credit Facility was secured by substantially all of our assets and material domestic subsidiaries. The 2016 Secured Credit Facility was used for general corporate purposes, and to replace, and repay remaining outstanding balances on our prior debt. Prepayment of the 2016 Secured Credit Facility was required upon the completion of the sale of Trillium in accordance with its amended terms. The proceeds of the Trillium sale were used to repay in full all outstanding loans, together with interest, and all other amounts due in connection with repayment (including prepayment penalties of approximately $1.3 million). The credit and guarantee agreements related to the 2016 Secured Credit Facility were likewise terminated. On April 17, 2017, we entered into a secured credit facility with Texas Capital Bank, N.A., that provides a $20 million revolving credit facility (the "Texas Capital Credit Facility"). The Texas Capital Credit Facility is being used for general corporate purposes and to provide collateral for up to $5.0 million of letters of credit issued by Texas Capital Bank. The Texas Capital Credit Facility is secured by substantially all of the company's assets and is guaranteed by HHS Guaranty, LLC, an entity formed to provide credit support for Harte Hanks by certain members of the Shelton family (descendants of one of our founders). On January 9, 2018, we entered into an amendment (the "First Amendment") to the Texas Capital Credit Facility. The First Amendment (i) increases the availability under the revolving credit facility from $20 million to $22 million and (ii) extends the Texas Capital Credit Facility one year to April 17, 2020. The Credit Facility remains secured by substantially all of our assets. Our fee for the collateral balance provided by HHS Guaranty, LLC also changed from an annual fee of $0.5 million to 0.5% of collateral actually pledged; we expect that the fees payable to HHS Guaranty will be substantially similar in amount under the new terms. Pursuant to the First Amendment, the Texas Capital Credit Facility expires on April 17, 2020 at which point all outstanding principal amounts will be due. Harte Hanks can elect to accrue interest on outstanding principal balances at either LIBOR plus 1.95% or prime plus 0.75%. Unused credit balances will accrue interest at 0.50%. The Texas Capital Credit Facility is subject to customary covenants requiring insurance, legal compliance, payment of taxes, prohibition of second liens, and secondary indebtedness, as well as the filing of quarterly and annual financial statements. We were in compliance with all of the covenants of our credit facility at December 31, 2017. Cash payments for interest were $0.3 million, $5.7 million, and $1.7 million for the years ended December 31, 2017, 2016, and 2015, respectively.

Long-Term Debt

As of December 31, 2017 the Texas Capital Facility was outstanding, but at each of of years ended December 31, 2017 and 2016, we had no debt outstanding.

Credit Facilities

On March 10, 2016, we entered into a secured credit facility with Wells Fargo Bank, N.A. as Administrative Agent, consisting of a maximum $65.0 million revolving credit facility (the "2016 Revolving Credit Facility"), and a $45.0 million term loan facility (the "2016 Term Loan", and together with the 2016 Revolving Credit Facility, the "2016 Secured Credit Facility"). The 2016 Secured Credit Facility was secured by substantially all of our assets and material domestic subsidiaries. The 2016 Secured Credit Facility was used for general corporate purposes, and to replace, and repay remaining outstanding balances on our prior debt.

Prepayment of the 2016 Secured Credit Facility was required upon the completion of the sale of Trillium in accordance with its amended terms. The proceeds of the Trillium sale were used to repay in full all outstanding loans, together with interest, and all other amounts due in connection with repayment (including prepayment penalties of approximately $1.3 million). The credit and guarantee agreements related to the 2016 Secured Credit Facility were likewise terminated.

On April 17, 2017, we entered into a secured credit facility with Texas Capital Bank, N.A., that provides a $20 million revolving credit facility (the "Texas Capital Credit Facility"). The Texas Capital Credit Facility is being used for general corporate purposes and to provide collateral for up to $5.0 million of letters of credit issued by Texas Capital Bank. The Texas Capital Credit Facility is secured by substantially all of the company's assets and is guaranteed by HHS Guaranty, LLC, an entity formed to provide credit support for Harte Hanks by certain members of the Shelton family (descendants of one of our founders).

On January 9, 2018, we entered into an amendment (the "First Amendment") to the Texas Capital Credit Facility. The First Amendment (i) increases the availability under the revolving credit facility from $20 million to $22 million and (ii) extends the Texas Capital Credit Facility one year to April 17, 2020. The Credit Facility remains secured by substantially all of our assets. Our fee for the collateral balance provided by HHS Guaranty, LLC also changed from an annual fee of $0.5 million to 0.5% of collateral actually pledged; we expect that the fees payable to HHS Guaranty will be substantially similar in amount under the new terms.

Pursuant to the First Amendment, the Texas Capital Credit Facility expires on April 17, 2020 at which point all outstanding principal amounts will be due. Harte Hanks can elect to accrue interest on outstanding principal balances at either LIBOR plus 1.95% or prime plus 0.75%. Unused credit balances will accrue interest at 0.50%.

The Texas Capital Credit Facility is subject to customary covenants requiring insurance, legal compliance, payment of taxes, prohibition of second liens, and secondary indebtedness, as well as the filing of quarterly and annual financial statements. We were in compliance with all of the covenants of our credit facility at December 31, 2017.

Cash payments for interest were $0.3 million, $5.7 million, and $1.7 million for the years ended December 31, 2017, 2016, and 2015, respectively.