<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.19.3.a.u2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>230</ContextCount>
  <ElementCount>482</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>59</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>100000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>100010 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>100020 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>100030 - Statement - Consolidated Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedStatementsOfOperations</Role>
      <ShortName>Consolidated Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>100040 - Statement - Consolidated Statements of Operations (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedStatementsOfOperationsParenthetical</Role>
      <ShortName>Consolidated Statements of Operations (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>100050 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>100060 - Statement - Consolidated Statements of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>Consolidated Statements of Shareholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>100070 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/StatementConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>100080 - Disclosure - Basis of Presentation and General Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformation</Role>
      <ShortName>Basis of Presentation and General Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>100090 - Disclosure - Fair Value Measurement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureFairValueMeasurement</Role>
      <ShortName>Fair Value Measurement</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>100100 - Disclosure - Accounts Receivable and Unbilled Revenue, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccountsReceivableAndUnbilledRevenueNet</Role>
      <ShortName>Accounts Receivable and Unbilled Revenue, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>100110 - Disclosure - Property and Equipment, Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNet</Role>
      <ShortName>Property and Equipment, Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>100120 - Disclosure - Accrued Expenses and Other Liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccruedExpensesAndOtherLiabilities</Role>
      <ShortName>Accrued Expenses and Other Liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>100130 - Disclosure - Restructuring Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCosts</Role>
      <ShortName>Restructuring Costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>100140 - Disclosure - Lease Commitments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitments</Role>
      <ShortName>Lease Commitments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>100150 - Disclosure - Credit Facility</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureCreditFacility</Role>
      <ShortName>Credit Facility</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>100160 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>100170 - Disclosure - Stock Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>100180 - Disclosure - Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureShareholdersEquity</Role>
      <ShortName>Shareholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>100190 - Disclosure - 401(k) Plan</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/Disclosure401KPlan</Role>
      <ShortName>401(k) Plan</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>100200 - Disclosure - Transactions with Related Parties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureTransactionsWithRelatedParties</Role>
      <ShortName>Transactions with Related Parties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>100210 - Disclosure - Litigation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLitigation</Role>
      <ShortName>Litigation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>100220 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>100230 - Disclosure - Geographic and Service Group Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformation</Role>
      <ShortName>Geographic and Service Group Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>100240 - Disclosure - Quarterly Financial Information (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnaudited</Role>
      <ShortName>Quarterly Financial Information (Unaudited)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>100250 - Disclosure - Schedule II - Valuation and Qualifying Accounts and Reserves</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureScheduleIIValuationAndQualifyingAccountsAndReserves</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts and Reserves</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>100260 - Disclosure - Basis of Presentation and General Information (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationPolicies</Role>
      <ShortName>Basis of Presentation and General Information (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>100270 - Disclosure - Basis of Presentation and General Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</Role>
      <ShortName>Basis of Presentation and General Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>100280 - Disclosure - Accounts Receivable and Unbilled Revenue, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccountsReceivableAndUnbilledRevenueNetTables</Role>
      <ShortName>Accounts Receivable and Unbilled Revenue, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccountsReceivableAndUnbilledRevenueNet</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>100290 - Disclosure - Property and Equipment, Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNetTables</Role>
      <ShortName>Property and Equipment, Net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNet</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>100300 - Disclosure - Accrued Expenses and Other Liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccruedExpensesAndOtherLiabilitiesTables</Role>
      <ShortName>Accrued Expenses and Other Liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccruedExpensesAndOtherLiabilities</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>100310 - Disclosure - Restructuring Costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCostsTables</Role>
      <ShortName>Restructuring Costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCosts</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>100320 - Disclosure - Lease Commitments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitmentsTables</Role>
      <ShortName>Lease Commitments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitments</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>100330 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxes</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>100340 - Disclosure - Stock Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensation</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>100350 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitions</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>100360 - Disclosure - Geographic and Service Group Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationTables</Role>
      <ShortName>Geographic and Service Group Information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformation</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>100370 - Disclosure - Quarterly Financial Information (Unaudited) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnauditedTables</Role>
      <ShortName>Quarterly Financial Information (Unaudited) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnaudited</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>100380 - Disclosure - Basis of Presentation and General Information (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationNarrativeDetails</Role>
      <ShortName>Basis of Presentation and General Information (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>100390 - Disclosure - Basis of Presentation and General Information (Carrying Amount And Activity Of Goodwill) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationCarryingAmountAndActivityOfGoodwillDetails</Role>
      <ShortName>Basis of Presentation and General Information (Carrying Amount And Activity Of Goodwill) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>100400 - Disclosure - Basis of Presentation and General Information (Components of Other Intangible Assets, Included In Other Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationComponentsOfOtherIntangibleAssetsIncludedInOtherAssetsDetails</Role>
      <ShortName>Basis of Presentation and General Information (Components of Other Intangible Assets, Included In Other Assets) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>100410 - Disclosure - Basis of Presentation and General Information (Summary of Disaggregation of Total Revenue from Continuing Operations Including Reimbursable Expenses (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationSummaryOfDisaggregationOfTotalRevenueFromContinuingOperationsIncludingReimbursableExpensesDetails</Role>
      <ShortName>Basis of Presentation and General Information (Summary of Disaggregation of Total Revenue from Continuing Operations Including Reimbursable Expenses (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>100420 - Disclosure - Basis of Presentation and General Information (Carrying Amounts of Major Classes of Assets and Liabilities Presented in Discontinued Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationCarryingAmountsOfMajorClassesOfAssetsAndLiabilitiesPresentedInDiscontinuedOperationsDetails</Role>
      <ShortName>Basis of Presentation and General Information (Carrying Amounts of Major Classes of Assets and Liabilities Presented in Discontinued Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>100430 - Disclosure - Basis of Presentation and General Information (Carrying Amounts of Major Classes of Assets and Liabilities Presented in Discontinued Operations) (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationCarryingAmountsOfMajorClassesOfAssetsAndLiabilitiesPresentedInDiscontinuedOperationsParentheticalDetails</Role>
      <ShortName>Basis of Presentation and General Information (Carrying Amounts of Major Classes of Assets and Liabilities Presented in Discontinued Operations) (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>100440 - Disclosure - Basis of Presentation and General Information (Gain and Loss Results for Discontinued Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationGainAndLossResultsForDiscontinuedOperationsDetails</Role>
      <ShortName>Basis of Presentation and General Information (Gain and Loss Results for Discontinued Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>100450 - Disclosure - Basis of Presentation and General Information (Reconciliation of Basic and Diluted Weighted Average Shares) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationReconciliationOfBasicAndDilutedWeightedAverageSharesDetails</Role>
      <ShortName>Basis of Presentation and General Information (Reconciliation of Basic and Diluted Weighted Average Shares) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureBasisOfPresentationAndGeneralInformationTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>100460 - Disclosure - Accounts Receivable and Unbilled Revenue, Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccountsReceivableAndUnbilledRevenueNetDetails</Role>
      <ShortName>Accounts Receivable and Unbilled Revenue, Net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccountsReceivableAndUnbilledRevenueNetTables</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>100470 - Disclosure - Property and Equipment, Net (Schedule of Property and Equipment) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNetScheduleOfPropertyAndEquipmentDetails</Role>
      <ShortName>Property and Equipment, Net (Schedule of Property and Equipment) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNetTables</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>100480 - Disclosure - Property and Equipment, Net (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNetNarrativeDetails</Role>
      <ShortName>Property and Equipment, Net (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosurePropertyAndEquipmentNetTables</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>100490 - Disclosure - Accrued Expenses and Other Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccruedExpensesAndOtherLiabilitiesDetails</Role>
      <ShortName>Accrued Expenses and Other Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAccruedExpensesAndOtherLiabilitiesTables</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>100500 - Disclosure - Restructuring Costs (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCostsNarrativeDetails</Role>
      <ShortName>Restructuring Costs (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCostsTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>100510 - Disclosure - Restructuring Costs (Schedule of Activity in Restructuring Expense Accruals) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCostsScheduleOfActivityInRestructuringExpenseAccrualsDetails</Role>
      <ShortName>Restructuring Costs (Schedule of Activity in Restructuring Expense Accruals) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureRestructuringCostsTables</ParentRole>
      <Position>52</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>100520 - Disclosure - Lease Commitments (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitmentsNarrativeDetails</Role>
      <ShortName>Lease Commitments (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitmentsTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>100530 - Disclosure - Lease Commitments (Future Minimum Lease Commitments Under Non-Cancelable Operating Leases) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitmentsFutureMinimumLeaseCommitmentsUnderNonCancelableOperatingLeasesDetails</Role>
      <ShortName>Lease Commitments (Future Minimum Lease Commitments Under Non-Cancelable Operating Leases) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureLeaseCommitmentsTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>100540 - Disclosure - Credit Facility (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureCreditFacilityNarrativeDetails</Role>
      <ShortName>Credit Facility (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureCreditFacility</ParentRole>
      <Position>55</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>100550 - Disclosure - Income Taxes (Components of Income (Loss) Before Income Taxes from Continuing Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesComponentsOfIncomeLossBeforeIncomeTaxesFromContinuingOperationsDetails</Role>
      <ShortName>Income Taxes (Components of Income (Loss) Before Income Taxes from Continuing Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>56</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>100560 - Disclosure - Income Taxes (Components of Income Tax Expense (Benefit) from Continuing Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesComponentsOfIncomeTaxExpenseBenefitFromContinuingOperationsDetails</Role>
      <ShortName>Income Taxes (Components of Income Tax Expense (Benefit) from Continuing Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>57</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>100570 - Disclosure - Income Taxes (Reconciliation of The Federal Statutory Tax Rate With The Effective Tax Rate from Continuing Operations) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesReconciliationOfTheFederalStatutoryTaxRateWithTheEffectiveTaxRateFromContinuingOperationsDetails</Role>
      <ShortName>Income Taxes (Reconciliation of The Federal Statutory Tax Rate With The Effective Tax Rate from Continuing Operations) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>58</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>100580 - Disclosure - Income Taxes (Components of The Net Deferred Income Tax Asset (Liability)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesComponentsOfTheNetDeferredIncomeTaxAssetLiabilityDetails</Role>
      <ShortName>Income Taxes (Components of The Net Deferred Income Tax Asset (Liability)) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>59</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>100590 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>60</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>100600 - Disclosure - Income Taxes (Detail and Activity of The ASC 740-10 Liability) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesDetailAndActivityOfTheASC74010LiabilityDetails</Role>
      <ShortName>Income Taxes (Detail and Activity of The ASC 740-10 Liability) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureIncomeTaxesTables</ParentRole>
      <Position>61</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>100610 - Disclosure - Stock Based Compensation (Schedule of Share Based Compensation Included in Net Income) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationScheduleOfShareBasedCompensationIncludedInNetIncomeDetails</Role>
      <ShortName>Stock Based Compensation (Schedule of Share Based Compensation Included in Net Income) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>62</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>100620 - Disclosure - Stock Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock Based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>63</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>100630 - Disclosure - Stock Based Compensation (Summary of Stock Option Activity Under The Company's Stock Option Plans) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityUnderTheCompanySStockOptionPlansDetails</Role>
      <ShortName>Stock Based Compensation (Summary of Stock Option Activity Under The Company's Stock Option Plans) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>64</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>100640 - Disclosure - Stock Based Compensation (Other Information Pertaining To Stock Option Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationOtherInformationPertainingToStockOptionActivityDetails</Role>
      <ShortName>Stock Based Compensation (Other Information Pertaining To Stock Option Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>65</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>100650 - Disclosure - Stock Based Compensation - SAR Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationSARActivityDetails</Role>
      <ShortName>Stock Based Compensation - SAR Activity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>100660 - Disclosure - Stock Based Compensation (Summary of Restricted Stock Unit Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationSummaryOfRestrictedStockUnitActivityDetails</Role>
      <ShortName>Stock Based Compensation (Summary of Restricted Stock Unit Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>67</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>100670 - Disclosure - Stock Based Compensation (Summary of Activity For Common Stock Subject To Vesting Requirements) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationSummaryOfActivityForCommonStockSubjectToVestingRequirementsDetails</Role>
      <ShortName>Stock Based Compensation (Summary of Activity For Common Stock Subject To Vesting Requirements) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>68</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>100680 - Disclosure - Shareholders' Equity (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureShareholdersEquityNarrativeDetails</Role>
      <ShortName>Shareholders' Equity (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureShareholdersEquity</ParentRole>
      <Position>69</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>100690 - Disclosure - 401(k) Plan (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/Disclosure401KPlanDetails</Role>
      <ShortName>401(k) Plan (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/Disclosure401KPlan</ParentRole>
      <Position>70</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>100700 - Disclosure - Transactions With Related Parties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureTransactionsWithRelatedPartiesDetails</Role>
      <ShortName>Transactions With Related Parties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>100710 - Disclosure - Acquisitions (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsNarrativeDetails</Role>
      <ShortName>Acquisitions (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>100720 - Disclosure - Acquisitions (Purchase Price Allocation) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsPurchasePriceAllocationDetails</Role>
      <ShortName>Acquisitions (Purchase Price Allocation) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>73</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>100730 - Disclosure - Acquisitions (Intangible Assets Acquired) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsIntangibleAssetsAcquiredDetails</Role>
      <ShortName>Acquisitions (Intangible Assets Acquired) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>74</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>100740 - Disclosure - Geographic and Service Group Information (Geographic Revenue from Continuing Operations before Reimbursement) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationGeographicRevenueFromContinuingOperationsBeforeReimbursementDetails</Role>
      <ShortName>Geographic and Service Group Information (Geographic Revenue from Continuing Operations before Reimbursement) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationTables</ParentRole>
      <Position>75</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>100750 - Disclosure - Geographic and Service Group Information (Long-Lived Assets Attributable To Geographic Area) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationLongLivedAssetsAttributableToGeographicAreaDetails</Role>
      <ShortName>Geographic and Service Group Information (Long-Lived Assets Attributable To Geographic Area) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationTables</ParentRole>
      <Position>76</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>100760 - Disclosure - Geographic and Service Group Information (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationNarrativeDetails</Role>
      <ShortName>Geographic and Service Group Information (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureGeographicAndServiceGroupInformationTables</ParentRole>
      <Position>77</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>100770 - Disclosure - Quarterly Financial Information (Unaudited Supplemental Quarterly Financial Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnauditedSupplementalQuarterlyFinancialInformationDetails</Role>
      <ShortName>Quarterly Financial Information (Unaudited Supplemental Quarterly Financial Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnauditedTables</ParentRole>
      <Position>78</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>100780 - Disclosure - Quarterly Financial Information (Unaudited Supplemental Quarterly Financial Information) (Parenthetical) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnauditedSupplementalQuarterlyFinancialInformationParentheticalDetails</Role>
      <ShortName>Quarterly Financial Information (Unaudited Supplemental Quarterly Financial Information) (Parenthetical) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureQuarterlyFinancialInformationUnauditedTables</ParentRole>
      <Position>79</Position>
    </Report>
    <Report instance="hckt-20191227.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>100790 - Disclosure - Schedule II - Valuation and Qualifying Accounts and Reserves (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureScheduleIIValuationAndQualifyingAccountsAndReservesDetails</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts and Reserves (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.thehackettgroup.com/20191227/taxonomy/role/DisclosureScheduleIIValuationAndQualifyingAccountsAndReserves</ParentRole>
      <Position>80</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>hckt-20191227.xml</File>
    <File>hckt-20191227.xsd</File>
    <File>hckt-20191227_cal.xml</File>
    <File>hckt-20191227_def.xml</File>
    <File>hckt-20191227_lab.xml</File>
    <File>hckt-20191227_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
