Basis Of Presentation And General Information (Policies)	3 Months Ended
	Apr. 01, 2016
Basis Of Presentation And General Information [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements of The Hackett Group, Inc. (“Hackett” or the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and include the Company’s accounts and those of its wholly-owned subsidiaries which the Company is required to consolidate. All intercompany transactions and balances have been eliminated in consolidation. In the opinion of management, the accompanying consolidated financial statements reflect all normal and recurring adjustments which are necessary for a fair presentation of the Company’s financial position, results of operations, and cash flows as of the dates and for the periods presented. The consolidated financial statements have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) regarding interim financial reporting. Accordingly, these statements do not include all the disclosures normally required by U.S. GAAP for annual financial statements and should be read in conjunction with the consolidated financial statements and notes thereto for the year ended January 1, 2016, included in the Annual Report on Form 10-K filed by the Company with the SEC. The consolidated results of operations for the quarter ended April 1, 2016, are not necessarily indicative of the results to be expected for any future period or for the full fiscal year.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from those estimates.
Fair Value	Fair Value The Company’s financial instruments consist of cash and cash equivalents, accounts receivable and unbilled revenue, accounts payable, accrued expenses and other liabilities and debt. As of April 1, 2016 and January 1, 2016, the carrying amount of each financial instrument approximated the instrument’s respective fair value due to the short-term nature and maturity of these instruments. The Company uses significant other observable market data or assumptions (Level 2 inputs as defined in accounting guidance) that it believes market participants would use in pricing debt. The fair value of the debt approximated the carrying amount, using Level 2 inputs, due to the short-term variable interest rates based on market rates.
Business Combinations	Business Combinations The Company applies the provisions of ASC 805, Business Combinations, in the accounting for its acquisitions, which requires recognition of the assets acquired and the liabilities assumed at their acquisition date fair values, separately from goodwill. Goodwill as of the acquisition date is measured as the excess of consideration transferred and the net of the acquisition date fair values of the tangible and identifiable intangible assets acquired and liabilities assumed. While the Company uses its best estimates and assumptions to accurately value assets acquired and liabilities assumed at the acquisition date as well as contingent consideration, where applicable, its estimates are inherently uncertain and subject to refinement. As a result, during the measurement period, that may be up to 12 months from the acquisition date, the Company records adjustments to the assets acquired and liabilities assumed with a corresponding adjustment to goodwill. Upon the conclusion of the measurement period or final determination of the values of assets acquired or liabilities assumed, whichever comes first, the impact of any subsequent adjustments is included in the consolidated statements of operations.
Recently Issued Accounting Standards	Recently Issued Accounting Standards In May 2014, the FASB issued guidance on revenue recognition, which provides for a single, principles-based model for revenue recognition and replaces the existing revenue recognition guidance. The guidance is effective for annual and interim periods beginning on or after December 15, 2017 and will replace most existing revenue recognition guidance under U.S. GAAP when it becomes effective. It permits the use of either a retrospective or cumulative effect transition method and early adoption is permitted, however not before December 15, 2016. The Company has not yet selected a transition method and is in the process of evaluating the effect this standard will have on its consolidated financial statements and related disclosures. In April 2015, the FASB issued amendments to its guidance which are intended to simplify the balance sheet presentation of debt issuance costs. These amendments require that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of the debt liability, consistent with debt discounts. The recognition and measurement guidance for debt issuance costs are not affected by this update. The amendments are effective for annual and interim periods beginning after December 15, 2015 and requires a retrospective transition method. Early adoption is permitted for financial statements that have not been previously issued. This adoption did not have a material impact on the Company’s consolidated financial statements. On November 20, 2015, the FASB issued guidance which requires an entity to present all deferred tax assets and liabilities as non-current in a classified balance sheet. The update becomes effective January 1, 2017, however early adoption is permitted. The Company chose early adoption for the periods presented. In February 2016, the FASB issued guidance on leases which supersedes the current lease guidance. The core principle requires lessees to recognize the assets and liabilities that arise from nearly all leases in the statement of financial position. Accounting applied by lessors will remain largely consistent with previous guidance, additional changes set to align lessor accounting with the revised lessee model and the FASB’s revenue recognition guidance. The amendments are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The Company is currently assessing the impact of this standard on its consolidated financial statements. In March 2016, the FASB issued guidance on employee share-based payment accounting, The goal of which is to simplify several aspects of the accounting for share-based payment transactions, including the income tax consequences, classification of awards as either equity or liabilities and classification on the statement of cash flows. This update becomes effective for annual and interim periods beginning after December 15, 2016, with early adoption permitted. The Company is currently evaluating the impact of this new guidance.
Reclassifications	Reclassifications Certain prior period amounts in the consolidated financial statements, and notes thereto, have been reclassified to conform to current period presentation. The Company reclassified on the Consolidated Statements of Cash Flows the dollar value of shares having a value equal to tax withholding, which were withheld and never issued. In lieu of issuing the shares, taxes were paid on the employee’s behalf. In the first quarter of 2016 and 2015, $3.4 million and $2.1 million, respectively, related to the net shares withheld was reclassified from cash flows from operations to cash flows from financing activities to conform to current period presentation.