<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.20.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>220</ContextCount>
  <ElementCount>389</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>50</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - Condensed Consolidated Statements Of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedStatementsOfIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - Condensed Consolidated Statements Of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00305 - Statement - Condensed Consolidated Statements Of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeParenthetical</Role>
      <ShortName>Condensed Consolidated Statements Of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00400 - Statement - Condensed Consolidated Statements Of Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>Condensed Consolidated Statements Of Shareholders' Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>00500 - Statement - Condensed Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements Of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Basis Of Presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureBasisOfPresentation</Role>
      <ShortName>Basis Of Presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Revenue</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRevenue</Role>
      <ShortName>Revenue</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Net Income Per Share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureNetIncomePerShare</Role>
      <ShortName>Net Income Per Share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Stock-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensation</Role>
      <ShortName>Stock-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Fair Value</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureFairValue</Role>
      <ShortName>Fair Value</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeases</Role>
      <ShortName>Leases</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Shareholders' Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureShareholdersEquity</Role>
      <ShortName>Shareholders' Equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Restructuring and Other Related Costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRestructuringAndOtherRelatedCosts</Role>
      <ShortName>Restructuring and Other Related Costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Product Warranties</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureProductWarranties</Role>
      <ShortName>Product Warranties</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Legal Proceedings</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLegalProceedings</Role>
      <ShortName>Legal Proceedings</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11301 - Disclosure - Subsequent Events</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>Subsequent Events</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>20102 - Disclosure - Basis Of Presentation (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureBasisOfPresentationPolicy</Role>
      <ShortName>Basis Of Presentation (Policy)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Revenue (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRevenueTables</Role>
      <ShortName>Revenue (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureRevenue</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Net Income Per Share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureNetIncomePerShareTables</Role>
      <ShortName>Net Income Per Share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureNetIncomePerShare</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Stock-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</Role>
      <ShortName>Stock-Based Compensation (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensation</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureDebt</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeases</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Basis Of Presentation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureBasisOfPresentationDetails</Role>
      <ShortName>Basis Of Presentation (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureBasisOfPresentationPolicy</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Revenue (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRevenueNarrativeDetails</Role>
      <ShortName>Revenue (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureRevenueTables</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Revenue (Schedule Of Disaggregation Of Revenue) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRevenueScheduleOfDisaggregationOfRevenueDetails</Role>
      <ShortName>Revenue (Schedule Of Disaggregation Of Revenue) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureRevenueTables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Net Income Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureNetIncomePerShareDetails</Role>
      <ShortName>Net Income Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureNetIncomePerShareTables</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Stock-Based Compensation (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationNarrativeDetails</Role>
      <ShortName>Stock-Based Compensation (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40402 - Disclosure - Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationScheduleOfStockBasedCompensationExpenseDetails</Role>
      <ShortName>Stock-Based Compensation (Schedule Of Stock-Based Compensation Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40403 - Disclosure - Stock-Based Compensation (Schedule Of Option Grant Fair Value Assumptions) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationScheduleOfOptionGrantFairValueAssumptionsDetails</Role>
      <ShortName>Stock-Based Compensation (Schedule Of Option Grant Fair Value Assumptions) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40404 - Disclosure - Stock-Based Compensation (Summary Of Stock Option Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationSummaryOfStockOptionActivityDetails</Role>
      <ShortName>Stock-Based Compensation (Summary Of Stock Option Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40407 - Disclosure - Stock-Based Compensation (Summary Of Non-Vested Share Award Activity) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationSummaryOfNonVestedShareAwardActivityDetails</Role>
      <ShortName>Stock-Based Compensation (Summary Of Non-Vested Share Award Activity) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureStockBasedCompensationTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureFairValueDetails</Role>
      <ShortName>Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureFairValue</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Debt (Revolving Credit Facilities) (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebtRevolvingCreditFacilitiesNarrativeDetails</Role>
      <ShortName>Debt (Revolving Credit Facilities) (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureDebtTables</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>40603 - Disclosure - Debt (Shelf Facility Agreements) (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebtShelfFacilityAgreementsNarrativeDetails</Role>
      <ShortName>Debt (Shelf Facility Agreements) (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureDebtTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>40604 - Disclosure - Debt (Financing Arrangements) (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebtFinancingArrangementsNarrativeDetails</Role>
      <ShortName>Debt (Financing Arrangements) (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureDebtTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>40605 - Disclosure - Debt (Schedule Of Debt) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureDebtScheduleOfDebtDetails</Role>
      <ShortName>Debt (Schedule Of Debt) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureDebtTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>40702 - Disclosure - Leases (Components Of Lease Expense) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesComponentsOfLeaseExpenseDetails</Role>
      <ShortName>Leases (Components Of Lease Expense) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeasesTables</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>40703 - Disclosure - Leases (Supplemental Balance Sheet Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesSupplementalBalanceSheetInformationDetails</Role>
      <ShortName>Leases (Supplemental Balance Sheet Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeasesTables</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>40705 - Disclosure - Leases (Supplemental Cash Flow Information) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesSupplementalCashFlowInformationDetails</Role>
      <ShortName>Leases (Supplemental Cash Flow Information) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeasesTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40706 - Disclosure - Leases (Schedule Of Future Lease Payments) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesScheduleOfFutureLeasePaymentsDetails</Role>
      <ShortName>Leases (Schedule Of Future Lease Payments) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeasesTables</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40707 - Disclosure - Leases (Schedule Of Future Lease Payments Under Prior Standard) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureLeasesScheduleOfFutureLeasePaymentsUnderPriorStandardDetails</Role>
      <ShortName>Leases (Schedule Of Future Lease Payments Under Prior Standard) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureLeasesTables</ParentRole>
      <Position>46</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Shareholders' Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureShareholdersEquityDetails</Role>
      <ShortName>Shareholders' Equity (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureShareholdersEquity</ParentRole>
      <Position>47</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Restructuring and Other Related Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureRestructuringAndOtherRelatedCostsDetails</Role>
      <ShortName>Restructuring and Other Related Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureRestructuringAndOtherRelatedCosts</ParentRole>
      <Position>48</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Product Warranties (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureProductWarrantiesDetails</Role>
      <ShortName>Product Warranties (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureProductWarranties</ParentRole>
      <Position>49</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureIncomeTaxesDetails</Role>
      <ShortName>Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>50</Position>
    </Report>
    <Report instance="msm-20200530x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>41301 - Disclosure - Subsequent Events (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www1.mscdirect.com/role/DisclosureSubsequentEventsDetails</Role>
      <ShortName>Subsequent Events (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www1.mscdirect.com/role/DisclosureSubsequentEvents</ParentRole>
      <Position>51</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="msm-20200530x10q.htm">msm-20200530x10q.htm</File>
    <File>msm-20200530.xsd</File>
    <File>msm-20200530_cal.xml</File>
    <File>msm-20200530_def.xml</File>
    <File>msm-20200530_lab.xml</File>
    <File>msm-20200530_pre.xml</File>
    <File>msm-20200530xex10_1.htm</File>
    <File>msm-20200530xex10_2.htm</File>
    <File>msm-20200530xex31_1.htm</File>
    <File>msm-20200530xex31_2.htm</File>
    <File>msm-20200530xex32_1.htm</File>
    <File>msm-20200530xex32_2.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://fasb.org/srt/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2019-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2019-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
