<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>157</ContextCount>
  <ElementCount>204</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>38</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>5</UnitCount>
  <MyReports>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Condensed Consolidated Statements Of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedStatementsOfIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00200 - Statement - Condensed Consolidated Statements Of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Condensed Consolidated Statements Of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00205 - Statement - Condensed Consolidated Statements Of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncomeParenthetical</Role>
      <ShortName>Condensed Consolidated Statements Of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00300 - Statement - Condensed Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00305 - Statement - Condensed Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00400 - Statement - Condensed Consolidated Statements Of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Condensed Consolidated Statements Of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>00500 - Statement - Condensed Consolidated Statements Of Changes In Shareholders’ Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/StatementCondensedConsolidatedStatementsOfChangesInShareholdersEquity</Role>
      <ShortName>Condensed Consolidated Statements Of Changes In Shareholders’ Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Description Of The Business</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureDescriptionOfBusiness</Role>
      <ShortName>Description Of The Business</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Summary Of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary Of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Revenue</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureRevenue</Role>
      <ShortName>Revenue</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Property</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureProperty</Role>
      <ShortName>Property</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureDebt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Pension And Other Postretirement Benefits</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefits</Role>
      <ShortName>Pension And Other Postretirement Benefits</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Capital Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureCapitalStock</Role>
      <ShortName>Capital Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Accumulated Other Comprehensive Loss</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLoss</Role>
      <ShortName>Accumulated Other Comprehensive Loss</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Commitments And Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments And Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAcquisitions</Role>
      <ShortName>Acquisitions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Intangible Assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureIntangibleAssets</Role>
      <ShortName>Intangible Assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>20202 - Disclosure - Summary Of Significant Accounting Policies (Policy)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicy</Role>
      <ShortName>Summary Of Significant Accounting Policies (Policy)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureSummaryOfSignificantAccountingPolicies</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Revenue (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureRevenueTables</Role>
      <ShortName>Revenue (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureRevenue</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Property (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePropertyTables</Role>
      <ShortName>Property (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureProperty</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Pension And Other Postretirement Benefits (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefitsTables</Role>
      <ShortName>Pension And Other Postretirement Benefits (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefits</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30903 - Disclosure - Accumulated Other Comprehensive Loss (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLossTables</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLoss</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>31103 - Disclosure - Acquisitions (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAcquisitionsTables</Role>
      <ShortName>Acquisitions (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAcquisitions</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>31203 - Disclosure - Intangible Assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureIntangibleAssetsTables</Role>
      <ShortName>Intangible Assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureIntangibleAssets</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Revenue (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureRevenueNarrativeDetails</Role>
      <ShortName>Revenue (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureRevenueTables</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>40302 - Disclosure - Revenue (Disaggregation Of Revenue) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureRevenueDisaggregationOfRevenueDetails</Role>
      <ShortName>Revenue (Disaggregation Of Revenue) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureRevenueTables</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Property (Carrying Value Of Property) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePropertyCarryingValueOfPropertyDetails</Role>
      <ShortName>Property (Carrying Value Of Property) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosurePropertyTables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Income Taxes (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureIncomeTaxesNarrativeDetails</Role>
      <ShortName>Income Taxes (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureIncomeTaxes</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Debt (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureDebtNarrativeDetails</Role>
      <ShortName>Debt (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureDebt</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Pension And Other Postretirement Benefits (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefitsNarrativeDetails</Role>
      <ShortName>Pension And Other Postretirement Benefits (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefitsTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40702 - Disclosure - Pension And Other Postretirement Benefits (Schedule Of Net Periodic Benefit Costs) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefitsScheduleOfNetPeriodicBenefitCostsDetails</Role>
      <ShortName>Pension And Other Postretirement Benefits (Schedule Of Net Periodic Benefit Costs) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosurePensionAndOtherPostretirementBenefitsTables</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Capital Stock (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureCapitalStockNarrativeDetails</Role>
      <ShortName>Capital Stock (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureCapitalStock</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Accumulated Other Comprehensive Loss (Reclassification Out Of Accumulated Other Comprehensive Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLossReclassificationOutOfAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Reclassification Out Of Accumulated Other Comprehensive Income (Loss)) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLossTables</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>40902 - Disclosure - Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income (Loss)) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLossChangesInAccumulatedOtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Accumulated Other Comprehensive Loss (Changes In Accumulated Other Comprehensive Income (Loss)) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAccumulatedOtherComprehensiveLossTables</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Commitments And Contingencies (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureCommitmentsAndContingenciesNarrativeDetails</Role>
      <ShortName>Commitments And Contingencies (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Acquisitions (Narrative) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAcquisitionsNarrativeDetails</Role>
      <ShortName>Acquisitions (Narrative) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>41102 - Disclosure - Acquisitions (Preliminary Purchase Price Allocation) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureAcquisitionsPreliminaryPurchasePriceAllocationDetails</Role>
      <ShortName>Acquisitions (Preliminary Purchase Price Allocation) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureAcquisitionsTables</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Intangible Assets (Summary Of Intangible Assets) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.graybar.com/role/DisclosureIntangibleAssetsSummaryOfIntangibleAssetsDetails</Role>
      <ShortName>Intangible Assets (Summary Of Intangible Assets) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.graybar.com/role/DisclosureIntangibleAssetsTables</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="c402-20260630x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>c402-20260630.xsd</File>
    <File>c402-20260630_cal.xml</File>
    <File>c402-20260630_def.xml</File>
    <File>c402-20260630_lab.xml</File>
    <File>c402-20260630_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="c402-20260630x10q.htm">c402-20260630x10q.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>c402-20260630x10qg001.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="609">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="26">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="4">http://xbrl.sec.gov/ecd/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
