<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.6.0.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>308</ContextCount>
  <ElementCount>391</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>83</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000100 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>010000 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>010100 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>020000 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedStatementsOfOperations</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF OPERATIONS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>030000 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedStatementsOfComprehensiveLoss</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>040000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>050000 - Statement - CONSOLIDATED STATEMENTS OF SHAREHOLDERS EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF SHAREHOLDERS EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>060100 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SummaryOfSignificantAccountingPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>060200 - Disclosure - ACQUISITIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/Acquisitions</Role>
      <ShortName>ACQUISITIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>060300 - Disclosure - DISPOSITION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/Disposition</Role>
      <ShortName>DISPOSITION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>060400 - Disclosure - GOODWILL AND INTANGIBLES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/GoodwillAndIntangibles</Role>
      <ShortName>GOODWILL AND INTANGIBLES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>060500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/PropertyPlantAndEquipment</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>060600 - Disclosure - CREDIT FACILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/CreditFacilities</Role>
      <ShortName>CREDIT FACILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>060700 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/AccruedExpensesAndOtherCurrentLiabilities</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>060800 - Disclosure - SPECIAL CHARGES, NET</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SpecialChargesNet</Role>
      <ShortName>SPECIAL CHARGES, NET</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>060900 - Disclosure - SHAREHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ShareholdersEquity</Role>
      <ShortName>SHAREHOLDERS' EQUITY</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>061000 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/IncomeTaxes</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>061100 - Disclosure - COMMITMENTS, CONTINGENCIES AND OTHER MATTERS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/CommitmentsContingenciesAndOtherMatters</Role>
      <ShortName>COMMITMENTS, CONTINGENCIES AND OTHER MATTERS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>061200 - Disclosure - SEGMENT AND RELATED INFORMATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SegmentAndRelatedInformation</Role>
      <ShortName>SEGMENT AND RELATED INFORMATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>061300 - Disclosure - QUARTERLY FINANCIAL DATA (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/QuarterlyFinancialDataUnaudited</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (UNAUDITED)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>061400 - Schedule - SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ScheduleIiValuationAndQualifyingAccounts</Role>
      <ShortName>SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>070100 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>080200 - Disclosure - ACQUISITIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/AcquisitionsTables</Role>
      <ShortName>ACQUISITIONS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>080300 - Disclosure - DISPOSITION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/DispositionTables</Role>
      <ShortName>DISPOSITION (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>080400 - Disclosure - GOODWILL AND INTANGIBLES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/GoodwillAndIntangiblesTables</Role>
      <ShortName>GOODWILL AND INTANGIBLES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>080500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/PropertyPlantAndEquipmentTables</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>080700 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/AccruedExpensesAndOtherCurrentLiabilitiesTables</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>080800 - Disclosure - SPECIAL CHARGES, NET (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SpecialChargesNetTables</Role>
      <ShortName>SPECIAL CHARGES, NET (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>080900 - Disclosure - SHAREHOLDERS' EQUITY (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ShareholdersEquityTables</Role>
      <ShortName>SHAREHOLDERS' EQUITY (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>081000 - Disclosure - INCOME TAXES (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/IncomeTaxesTables</Role>
      <ShortName>INCOME TAXES (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>081100 - Disclosure - COMMITMENTS, CONTINGENCIES AND OTHER MATTERS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/CommitmentsContingenciesAndOtherMattersTables</Role>
      <ShortName>COMMITMENTS, CONTINGENCIES AND OTHER MATTERS (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>081200 - Disclosure - SEGMENT AND RELATED INFORMATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SegmentAndRelatedInformationTables</Role>
      <ShortName>SEGMENT AND RELATED INFORMATION (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>081300 - Disclosure - QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/QuarterlyFinancialDataUnauditedTables</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (UNAUDITED) (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>090100 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>090200 - Disclosure - ACQUISITIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/AcquisitionsDetails</Role>
      <ShortName>ACQUISITIONS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>090300 - Disclosure - DISPOSITION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/DispositionDetails</Role>
      <ShortName>DISPOSITION (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>090400 - Disclosure - GOODWILL AND INTANGIBLES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/GoodwillAndIntangiblesDetails</Role>
      <ShortName>GOODWILL AND INTANGIBLES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>090500 - Disclosure - PROPERTY, PLANT AND EQUIPMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/PropertyPlantAndEquipmentDetails</Role>
      <ShortName>PROPERTY, PLANT AND EQUIPMENT (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>090600 - Disclosure - CREDIT FACILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/CreditFacilitiesDetails</Role>
      <ShortName>CREDIT FACILITIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>090700 - Disclosure - ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/AccruedExpensesAndOtherCurrentLiabilitiesDetails</Role>
      <ShortName>ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>090800 - Disclosure - SPECIAL CHARGES, NET (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SpecialChargesNetDetails</Role>
      <ShortName>SPECIAL CHARGES, NET (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>090900 - Disclosure - SHAREHOLDERS' EQUITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ShareholdersEquityDetails</Role>
      <ShortName>SHAREHOLDERS' EQUITY (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>091000 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/IncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>091100 - Disclosure - COMMITMENTS, CONTINGENCIES AND OTHER MATTERS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/CommitmentsContingenciesAndOtherMattersDetails</Role>
      <ShortName>COMMITMENTS, CONTINGENCIES AND OTHER MATTERS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>091200 - Disclosure - SEGMENT AND RELATED INFORMATION, by Reportable Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SegmentAndRelatedInformationByReportableSegmentsDetails</Role>
      <ShortName>SEGMENT AND RELATED INFORMATION, by Reportable Segments (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>091202 - Disclosure - SEGMENT AND RELATED INFORMATION, by Geographic Area (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/SegmentAndRelatedInformationByGeographicAreaDetails</Role>
      <ShortName>SEGMENT AND RELATED INFORMATION, by Geographic Area (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>091300 - Disclosure - QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/QuarterlyFinancialDataUnauditedDetails</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="syx-20161231.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>091400 - Schedule - SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://systemax.com/role/ScheduleIiValuationAndQualifyingAccountsDetails</Role>
      <ShortName>SCHEDULE II VALUATION AND QUALIFYING ACCOUNTS (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>syx-20161231.xml</File>
    <File>syx-20161231.xsd</File>
    <File>syx-20161231_cal.xml</File>
    <File>syx-20161231_def.xml</File>
    <File>syx-20161231_lab.xml</File>
    <File>syx-20161231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
