Basis of Presentation (Policies)	9 Months Ended
Basis of Presentation (Policies)	Sep. 30, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Consolidation	Consolidation The accompanying unaudited Condensed Consolidated Financial Statements include the accounts of Harte Hanks, Inc. and subsidiaries. All intercompany accounts and transactions have been eliminated in consolidation. As used in this report, the terms “Harte Hanks,” “the company,” “we,” “us,” or “our” may refer to Harte Hanks, Inc., one or more of its consolidated subsidiaries, or all of them taken as a whole.
Interim Financial Information	Interim Financial Information The financial statements have been prepared in accordance with United States Generally Accepted Accounting Principles ("U.S. GAAP") for interim financial information and with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. Operating results for the three and nine months ended September 30, 2017 are not necessarily indicative of the results that may be expected for the year ending December 31, 2017. The information included in this Form 10-Q should be read in conjunction with Management’s Discussion and Analysis of Financial Condition and Results of Operations and the consolidated financial statements and notes thereto included in our annual report on Form 10-K for the year ended December 31, 2016.
Discontinued Operations	Discontinued Operations As discussed in Note M, Discontinued Operations, we sold the assets of Trillium Software, Inc. and its subsidiaries (collectively "Trillium") as of December 23, 2016. As such, the results of operations, financial position, and cash flows for Trillium are reported separately as discontinued operations for the three and nine months ended September 30, 2016 presented in the Condensed Consolidated Financial Statements. Results of the remaining Harte Hanks business are reported as continuing operations.
Going Concern	Going Concern Our recent operating and financial performance has caused us to closely review our ability to continue as a going concern. We have taken a number of actions to continue to support our operations and meet obligations in light of our recent financial performance and decreased cash flows. On April 17, 2017, we entered into a new credit agreement with Texas Capital Bank, N.A. (the "Texas Capital Credit Facility"). The Texas Capital Credit Facility provides $20.0 million in borrowing capacity under a revolving credit line with limited financial covenants compared to our previous credit facilities. We believe that the liquidity provided by the Texas Capital Credit Facility is sufficient for our needs given the nature and performance of our operations. On May 1, 2017, we entered into an agreement with 3Q Digital (the "3Q Agreement") which allows us to defer payment of the significant contingent liability that otherwise would have been due in 2018. Under the terms of the 3Q Digital purchase agreement, we are required to pay the former owners of 3Q Digital up to $35.0 million of additional consideration contingent on achievement of certain revenue growth goals. The 3Q Agreement defers our obligation to pay such contingent consideration until April 1, 2019, or the sale of the 3Q Digital business, whichever is earlier. We believe that in conjunction with our current liquidity position, the new credit facility, and the deferral of payment of the contingent consideration, there are no conditions or events, considered in the aggregate, that raise substantial doubt about our ability to continue as a going concern for the 12 months following the issuance of these unaudited Condensed Consolidated Financial Statements. We continue to take actions to return the business to profitability and improve our cash, liquidity, and financial position. We have implemented expense reduction actions, including downsizing our workforce and consolidating back-office and information technology functions. We completed the closure of our Baltimore direct mail facility in the first quarter of 2017 in response to the declining demand for printed marketing materials. Continuing work from this facility was transitioned to other facilities, allowing for higher utilization rates. We have started to see the favorable impact of these actions and intend to continue efforts to reduce expenses through the end of 2017. In addition to the actions discussed above, we are taking steps to improve our operational and financial performance. We continue to work toward increasing operating efficiencies and have focused our investments on improving product offerings that we believe will drive revenue growth. On April 18, 2017, we announced that as part of an initiative to enhance the company's strategic position and increase financial flexibility, the company would seek strategic alternatives for the 3Q Digital business. The liquidity from the potential sale of 3Q Digital would enhance our ability to invest in strategies to strengthen our core offerings.
Reclassifications	Reclassifications Certain amounts in the financial statements from the prior years have been reclassified to conform to the current year's presentation. This includes the retrospective adoption of ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, resulted in the reclassification of pension expense previously recorded in Labor as of September 30, 2016 to Other, net in the Condensed Consolidated Statements of Comprehensive Loss.
Use of Estimates	Use of Estimates The preparation of condensed consolidated financial statements requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenue, and expenses. Actual results and outcomes could differ from those estimates and assumptions. Such estimates include, but are not limited to, estimates related to pension accounting; fair value for purposes of assessing goodwill, long-lived assets, and intangible assets for impairment; income taxes; stock-based compensation; and contingencies. On an ongoing basis, management reviews its estimates based on currently available information. Changes in facts and circumstances could result in revised estimates and assumptions.
Inventory	Inventories Our inventories consist primarily of print material and operating supplies. Inventory is stated at the lower of cost using the first-in, first-out method, or market.
Operating Expense Presentation in Consolidated Statements of Comprehensive Income (Loss)	Operating Expense Presentation in Consolidated Statements of Comprehensive Loss “Labor” in the Consolidated Statements of Comprehensive Loss includes all employee payroll and benefits, including stock-based compensation, along with temporary labor costs. “Production and distribution” and “Advertising, selling, general and administrative” do not include labor, depreciation, or amortization.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation (Topic 718): Scope of Modification Accounting, which provides clarified guidance on applying modification accounting to changes in the terms or conditions of a share-based payment award. This ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017, with early adoption permitted. This change is required to be applied prospectively to an award modified on or after the adoption date. We are evaluating the effect that this will have on our consolidated financial statements and related disclosures. In March 2017, the FASB issued ASU 2017-07, Compensation—Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost, which requires entities to present the service cost component of net benefit cost with the other current compensation costs. All other components of net benefit cost are to be reported outside of operating income. This ASU is effective for annual periods beginning after December 15, 2017, with early adoption permitted. This change is required to be applied using a retrospective transition method for each period presented. We adopted the update as of the first quarter of 2017. As a result of the adoption of this ASU, we reclassified $1.5 million of pension expense recorded in Labor in the nine months ended September 30, 2016 to Other, net in the Condensed Consolidated Statements of Comprehensive Loss. In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment, which eliminates step two from the goodwill impairment test. Under the amendments in ASU 2017-04, an entity should recognize an impairment charge in the amount that the carrying amount of a reporting unit exceeds its fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit. This ASU is effective for annual or interim goodwill impairment tests in fiscal years beginning after December 15, 2019, with early adoption permitted. We adopted this standard in January 2017, and will apply it as necessary in our consolidated financial statements. In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments, which provides clarified guidance on the classification of certain cash receipts and payments in the statement of cash flows. This ASU is effective for annual periods beginning after December 15, 2017, including interim reporting periods within those annual reporting periods. This change is required to be applied using a retrospective transition method to each period presented. Early adoption is permitted. We are evaluating the effect that this will have on our consolidated financial statements and related disclosures. In March 2016, the FASB issued ASU 2016-09, Compensation—Stock Compensation (Topic 718): Improvements to Employee Share-based Payment Accounting, which requires entities with share-based payment awards to recognize all related excess tax benefits and tax deficiencies as income tax expenses or benefit in the income statement. This ASU is effective for interim and annual periods beginning after December 15, 2016. We have adopted the update as of the first quarter of 2017. As a result of the adoption of this ASU, excess tax benefits or deficiencies will now be reflected in the Condensed Consolidated Statements of Comprehensive Loss as a component of income taxes, whereas they previously would be recognized in equity. Excess tax benefits will be recognized in the Consolidated Statement of Cash Flow as an operating activity, with the prior periods adjusted accordingly. Finally, we have elected to account for forfeitures as they occur, rather than estimate expected forfeitures. The ASU was adopted on a modified retrospective basis and no prior periods were restated as a result of the change in accounting policy. In February 2016, the FASB issued ASU 2016-02, Leases, which requires all operating leases to be recorded on the balance sheet. The lessee will record a liability for its lease obligations (initially measured at the present value of the future lease payments not yet paid over the lease term, and an asset for its right to use the underlying asset equal to the lease liability, adjusted for lease payments made at or before lease commencement). This ASU is effective for interim and annual periods beginning after December 15, 2018, with early adoption permitted. This change is required to be applied using a modified retrospective approach for leases that exist or are entered into after the beginning of the earliest comparative period in the financial statements. Full retrospective application is prohibited. We are evaluating the effect that this will have on our consolidated financial statements and related disclosures. In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. GAAP when it becomes effective. The standard permits the use of either the retrospective or cumulative effect transition method. On July 9, 2015, the FASB delayed the effective date of the new revenue standard by one year. The new effective date is for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2017, with early adoption permitted beginning January 1, 2017. We are evaluating the effect that this will have on our consolidated financial statements and related disclosures. We have not yet selected a transition method nor have we determined the effect of the standard on our ongoing financial reporting.