<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>83</ContextCount>
  <ElementCount>282</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>37</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>8</UnitCount>
  <MyReports>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001001 - Document - COVER PAGE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/COVERPAGE</Role>
      <ShortName>COVER PAGE</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001002 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/CONSOLIDATEDBALANCESHEETS</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002003 - Statement - CONSOLIDATED BALANCE SHEETS (Parentheticals)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/CONSOLIDATEDBALANCESHEETSParentheticals</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parentheticals)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1003004 - Statement - CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/CONSOLIDATEDSTATEMENTSOFINCOME</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1004005 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/CONSOLIDATEDSTATEMENTSOFCASHFLOWS</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1005006 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Statement</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/CONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITYStatement</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY Statement</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>2101101 - Disclosure - ORGANIZATION</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ORGANIZATION</Role>
      <ShortName>ORGANIZATION</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2104102 - Disclosure - ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACCOUNTINGPOLICIES</Role>
      <ShortName>ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2115104 - Disclosure - ACQUISITIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACQUISITIONS</Role>
      <ShortName>ACQUISITIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2119105 - Disclosure - GOODWILL (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.wesco.com/role/GOODWILLNotes</Role>
      <ShortName>GOODWILL (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2122106 - Disclosure - STOCK-BASED COMPENSATION (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.wesco.com/role/STOCKBASEDCOMPENSATIONNotes</Role>
      <ShortName>STOCK-BASED COMPENSATION (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2130107 - Disclosure - EARNINGS PER SHARE</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EARNINGSPERSHARE</Role>
      <ShortName>EARNINGS PER SHARE</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2138109 - Disclosure - EMPLOYEE BENEFIT PLANS (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.wesco.com/role/EMPLOYEEBENEFITPLANSNotes</Role>
      <ShortName>EMPLOYEE BENEFIT PLANS (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2141110 - Disclosure - FAIR VALUE (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.wesco.com/role/FAIRVALUENotes</Role>
      <ShortName>FAIR VALUE (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2144111 - Disclosure - COMMITMENTS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/COMMITMENTSANDCONTINGENCIES</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2148112 - Disclosure - INCOME TAXES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/INCOMETAXES</Role>
      <ShortName>INCOME TAXES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2151113 - Disclosure - Subsequent Events (Notes)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.wesco.com/role/SubsequentEventsNotes</Role>
      <ShortName>Subsequent Events (Notes)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2205201 - Disclosure - ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACCOUNTINGPOLICIESPolicies</Role>
      <ShortName>ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2245204 - Disclosure - COMMITMENTS AND CONTINGENCIES Guarantee (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/COMMITMENTSANDCONTINGENCIESGuaranteePolicies</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES Guarantee (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2308301 - Disclosure - REVENUE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/REVENUETables</Role>
      <ShortName>REVENUE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2317302 - Disclosure - ACQUISITIONS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACQUISITIONSTables</Role>
      <ShortName>ACQUISITIONS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.wesco.com/role/ACQUISITIONS</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2320303 - Disclosure - GOODWILL (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/GOODWILLTables</Role>
      <ShortName>GOODWILL (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.wesco.com/role/GOODWILLNotes</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2323304 - Disclosure - STOCK-BASED COMPENSATION (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/STOCKBASEDCOMPENSATIONTables</Role>
      <ShortName>STOCK-BASED COMPENSATION (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.wesco.com/role/STOCKBASEDCOMPENSATIONNotes</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2331305 - Disclosure - EARNINGS PER SHARE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EARNINGSPERSHARETables</Role>
      <ShortName>EARNINGS PER SHARE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.wesco.com/role/EARNINGSPERSHARE</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2339307 - Disclosure - EMPLOYEE BENEFIT PLANS Schedule of Net Benefit Costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EMPLOYEEBENEFITPLANSScheduleofNetBenefitCostsTables</Role>
      <ShortName>EMPLOYEE BENEFIT PLANS Schedule of Net Benefit Costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2342308 - Disclosure - FAIR VALUE (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/FAIRVALUETables</Role>
      <ShortName>FAIR VALUE (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.wesco.com/role/FAIRVALUENotes</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2402401 - Disclosure - ORGANIZATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ORGANIZATIONDetails</Role>
      <ShortName>ORGANIZATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/ORGANIZATION</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2403402 - Disclosure - ORGANIZATION Organization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ORGANIZATIONOrganizationDetails</Role>
      <ShortName>ORGANIZATION Organization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACCOUNTINGPOLICIESDetails</Role>
      <ShortName>ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/ACCOUNTINGPOLICIESPolicies</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2409404 - Disclosure - REVENUE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/REVENUEDetails</Role>
      <ShortName>REVENUE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/REVENUETables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2410405 - Disclosure - REVENUE Deferred Revenue (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/REVENUEDeferredRevenueDetails</Role>
      <ShortName>REVENUE Deferred Revenue (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2411406 - Disclosure - REVENUE Shipping and Handling Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/REVENUEShippingandHandlingCostsDetails</Role>
      <ShortName>REVENUE Shipping and Handling Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2412407 - Disclosure - REVENUE Variable Consideration (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/REVENUEVariableConsiderationDetails</Role>
      <ShortName>REVENUE Variable Consideration (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2418409 - Disclosure - ACQUISITIONS - ACQUISITIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/ACQUISITIONSACQUISITIONSDetails</Role>
      <ShortName>ACQUISITIONS - ACQUISITIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2421410 - Disclosure - GOODWILL (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/GOODWILLDetails</Role>
      <ShortName>GOODWILL (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/GOODWILLTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2424411 - Disclosure - SCHEDULE OF SHARE-BASED COMPENSATION, STOCK OPTIONS AND STOCK APPRECIATION RIGHTS AWARD ACTIVITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SCHEDULEOFSHAREBASEDCOMPENSATIONSTOCKOPTIONSANDSTOCKAPPRECIATIONRIGHTSAWARDACTIVITYDetails</Role>
      <ShortName>SCHEDULE OF SHARE-BASED COMPENSATION, STOCK OPTIONS AND STOCK APPRECIATION RIGHTS AWARD ACTIVITY (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2425412 - Disclosure - SCHEDULE OF SHARE-BASED PAYMENT AWARD, VALUATION ASSUMPTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SCHEDULEOFSHAREBASEDPAYMENTAWARDVALUATIONASSUMPTIONSDetails</Role>
      <ShortName>SCHEDULE OF SHARE-BASED PAYMENT AWARD, VALUATION ASSUMPTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2426413 - Disclosure - SUMMARY OF RESTRICTED STOCK UNITS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SUMMARYOFRESTRICTEDSTOCKUNITSDetails</Role>
      <ShortName>SUMMARY OF RESTRICTED STOCK UNITS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2427414 - Disclosure - SUMMARY OF PERFORMANCE-BASED AWARDS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SUMMARYOFPERFORMANCEBASEDAWARDSDetails</Role>
      <ShortName>SUMMARY OF PERFORMANCE-BASED AWARDS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2428415 - Disclosure - SCHEDULE OF SHARE-BASED PAYMENT AWARD, PERFORMANCE-BASED AWARDS, VALUATION ASSUMPTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SCHEDULEOFSHAREBASEDPAYMENTAWARDPERFORMANCEBASEDAWARDSVALUATIONASSUMPTIONSDetails</Role>
      <ShortName>SCHEDULE OF SHARE-BASED PAYMENT AWARD, PERFORMANCE-BASED AWARDS, VALUATION ASSUMPTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2429416 - Disclosure - STOCK-BASED COMPENSATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/STOCKBASEDCOMPENSATIONDetails</Role>
      <ShortName>STOCK-BASED COMPENSATION (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/STOCKBASEDCOMPENSATIONTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2432417 - Disclosure - SCHEDULE OF EARNINGS PER SHARE, BASIC AND DILUTED (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SCHEDULEOFEARNINGSPERSHAREBASICANDDILUTEDDetails</Role>
      <ShortName>SCHEDULE OF EARNINGS PER SHARE, BASIC AND DILUTED (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2433418 - Disclosure - EARNINGS PER SHARE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EARNINGSPERSHAREDetails</Role>
      <ShortName>EARNINGS PER SHARE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/EARNINGSPERSHARETables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2434419 - Disclosure - EARNINGS PER SHARE Accelerated Share Repurchase (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EARNINGSPERSHAREAcceleratedShareRepurchaseDetails</Role>
      <ShortName>EARNINGS PER SHARE Accelerated Share Repurchase (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2440421 - Disclosure - EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS Pension Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/EMPLOYEEBENEFITPLANSEMPLOYEEBENEFITPLANSPensionCostsDetails</Role>
      <ShortName>EMPLOYEE BENEFIT PLANS EMPLOYEE BENEFIT PLANS Pension Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2443422 - Disclosure - FAIR VALUE (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/FAIRVALUEDetails</Role>
      <ShortName>FAIR VALUE (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/FAIRVALUETables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2447424 - Disclosure - COMMITMENTS AND CONTINGENCIES Guarantees (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/COMMITMENTSANDCONTINGENCIESGuaranteesDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENCIES Guarantees (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/COMMITMENTSANDCONTINGENCIESGuaranteePolicies</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2449425 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/INCOMETAXESDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/INCOMETAXES</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2450426 - Disclosure - INCOME TAXES Income Tax Rates (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/INCOMETAXESIncomeTaxRatesDetails</Role>
      <ShortName>INCOME TAXES Income Tax Rates (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="wcc-20200331.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2453427 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.wesco.com/role/SubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.wesco.com/role/SubsequentEventsNotes</ParentRole>
      <Position>50</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File doctype="10-Q" original="wcc-20200331.htm">wcc-20200331.htm</File>
    <File>wcc-1q20ex311.htm</File>
    <File>wcc-1q20ex312.htm</File>
    <File>wcc-1q20ex321.htm</File>
    <File>wcc-1q20ex322.htm</File>
    <File>wcc-20200331.xsd</File>
    <File>wcc-20200331_cal.xml</File>
    <File>wcc-20200331_def.xml</File>
    <File>wcc-20200331_lab.xml</File>
    <File>wcc-20200331_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>
