<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.26.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>186</ContextCount>
  <ElementCount>275</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>75</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>7</UnitCount>
  <MyReports>
    <Report instance="vhl-20260331x10q.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.valhi.net/20210930/taxonomy/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/StatementCondensedConsolidatedBalanceSheets</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00200 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/StatementCondensedConsolidatedStatementsOfIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00300 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/StatementCondensedConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00400 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/StatementCondensedConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00405 - Statement - CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/StatementConsolidatedStatementsOfStockholdersEquityParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00500 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/StatementCondensedConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>10101 - Disclosure - Organization and basis of presentation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOrganizationAndBasisOfPresentation</Role>
      <ShortName>Organization and basis of presentation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>10201 - Disclosure - Business segment information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformation</Role>
      <ShortName>Business segment information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>10301 - Disclosure - Accounts and other receivables, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureAccountsAndOtherReceivablesNet</Role>
      <ShortName>Accounts and other receivables, net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>10401 - Disclosure - Inventories, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureInventoriesNet</Role>
      <ShortName>Inventories, net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10501 - Disclosure - Marketable securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureMarketableSecurities</Role>
      <ShortName>Marketable securities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10601 - Disclosure - Other noncurrent assets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureOtherNoncurrentAssets</Role>
      <ShortName>Other noncurrent assets</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10701 - Disclosure - Long-term debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureLongTermDebt</Role>
      <ShortName>Long-term debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10801 - Disclosure - Accounts payable and accrued liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureAccountsPayableAndAccruedLiabilities</Role>
      <ShortName>Accounts payable and accrued liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10901 - Disclosure - Other noncurrent liabilities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentLiabilities</Role>
      <ShortName>Other noncurrent liabilities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>11001 - Disclosure - Revenue - disaggregation of sales</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureRevenueDisaggregationOfSales</Role>
      <ShortName>Revenue - disaggregation of sales</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>11101 - Disclosure - Defined benefit pension plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureDefinedBenefitPensionPlans</Role>
      <ShortName>Defined benefit pension plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>11201 - Disclosure - Other income, net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureOtherIncomeNet</Role>
      <ShortName>Other income, net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>11301 - Disclosure - Income taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureIncomeTaxes</Role>
      <ShortName>Income taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>11401 - Disclosure - Noncontrolling interest in subsidiaries</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureNoncontrollingInterestInSubsidiaries</Role>
      <ShortName>Noncontrolling interest in subsidiaries</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>11501 - Disclosure - Stockholders' equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureStockholdersEquity</Role>
      <ShortName>Stockholders' equity</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>11601 - Disclosure - Commitments and contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureCommitmentsAndContingencies</Role>
      <ShortName>Commitments and contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>11701 - Disclosure - Fair value measurements and financial instruments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureFairValueMeasurementsAndFinancialInstruments</Role>
      <ShortName>Fair value measurements and financial instruments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>11801 - Disclosure - Restructuring costs</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureRestructuringCosts</Role>
      <ShortName>Restructuring costs</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>11901 - Disclosure - Recent accounting pronouncements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureRecentAccountingPronouncements</Role>
      <ShortName>Recent accounting pronouncements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>20102 - Disclosure - Organization and basis of presentation (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureOrganizationAndBasisOfPresentationPolicies</Role>
      <ShortName>Organization and basis of presentation (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>30203 - Disclosure - Business segment information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformationTables</Role>
      <ShortName>Business segment information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformation</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>30303 - Disclosure - Accounts and other receivables, net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureAccountsAndOtherReceivablesNetTables</Role>
      <ShortName>Accounts and other receivables, net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureAccountsAndOtherReceivablesNet</ParentRole>
      <Position>29</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>30403 - Disclosure - Inventories, net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureInventoriesNetTables</Role>
      <ShortName>Inventories, net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureInventoriesNet</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>30503 - Disclosure - Marketable securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureMarketableSecuritiesTables</Role>
      <ShortName>Marketable securities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureMarketableSecurities</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>30603 - Disclosure - Other noncurrent assets (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentAssetsTables</Role>
      <ShortName>Other noncurrent assets (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureOtherNoncurrentAssets</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>30703 - Disclosure - Long-term debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureLongTermDebtTables</Role>
      <ShortName>Long-term debt (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureLongTermDebt</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>30803 - Disclosure - Accounts payable and accrued liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureAccountsPayableAndAccruedLiabilitiesTables</Role>
      <ShortName>Accounts payable and accrued liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureAccountsPayableAndAccruedLiabilities</ParentRole>
      <Position>34</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>30903 - Disclosure - Other noncurrent liabilities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentLiabilitiesTables</Role>
      <ShortName>Other noncurrent liabilities (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentLiabilities</ParentRole>
      <Position>35</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>31003 - Disclosure - Revenue - disaggregation of sales (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureRevenueDisaggregationOfSalesTables</Role>
      <ShortName>Revenue - disaggregation of sales (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureRevenueDisaggregationOfSales</ParentRole>
      <Position>36</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>31103 - Disclosure - Defined benefit pension plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureDefinedBenefitPensionPlansTables</Role>
      <ShortName>Defined benefit pension plans (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureDefinedBenefitPensionPlans</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>31203 - Disclosure - Other income, net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherIncomeNetTables</Role>
      <ShortName>Other income, net (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureOtherIncomeNet</ParentRole>
      <Position>38</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>31303 - Disclosure - Income taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureIncomeTaxesTables</Role>
      <ShortName>Income taxes (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureIncomeTaxes</ParentRole>
      <Position>39</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>31403 - Disclosure - Noncontrolling interest in subsidiaries (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureNoncontrollingInterestInSubsidiariesTables</Role>
      <ShortName>Noncontrolling interest in subsidiaries (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureNoncontrollingInterestInSubsidiaries</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>31503 - Disclosure - Stockholders' equity (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureStockholdersEquityTables</Role>
      <ShortName>Stockholders' equity (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureStockholdersEquity</ParentRole>
      <Position>41</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>31603 - Disclosure - Commitments and contingencies (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureCommitmentsAndContingenciesTables</Role>
      <ShortName>Commitments and contingencies (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureCommitmentsAndContingencies</ParentRole>
      <Position>42</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>31703 - Disclosure - Fair value measurements and financial instruments (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureFairValueMeasurementsAndFinancialInstrumentsTables</Role>
      <ShortName>Fair value measurements and financial instruments (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureFairValueMeasurementsAndFinancialInstruments</ParentRole>
      <Position>43</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>31803 - Disclosure - Restructuring costs (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureRestructuringCostsTables</Role>
      <ShortName>Restructuring costs (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureRestructuringCosts</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>40101 - Disclosure - Organization and basis of presentation - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOrganizationAndBasisOfPresentationAdditionalInformationDetails</Role>
      <ShortName>Organization and basis of presentation - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>40201 - Disclosure - Business segment information - Holding Percentage of Subsidiaries (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformationHoldingPercentageOfSubsidiariesDetails</Role>
      <ShortName>Business segment information - Holding Percentage of Subsidiaries (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>40202 - Disclosure - Business segment information - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformationAdditionalInformationDetails</Role>
      <ShortName>Business segment information - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>40203 - Disclosure - Business segment information - Segment Operating Performance (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureBusinessSegmentInformationSegmentOperatingPerformanceDetails</Role>
      <ShortName>Business segment information - Segment Operating Performance (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>40204 - Disclosure - Business segment information- Depreciation and Amortization (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureBusinessSegmentInformationDepreciationAndAmortizationDetails</Role>
      <ShortName>Business segment information- Depreciation and Amortization (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>40301 - Disclosure - Accounts and other receivables, net - Components of Accounts and Other Receivables (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureAccountsAndOtherReceivablesNetComponentsOfAccountsAndOtherReceivablesDetails</Role>
      <ShortName>Accounts and other receivables, net - Components of Accounts and Other Receivables (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>40401 - Disclosure - Inventories, net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureInventoriesNetDetails</Role>
      <ShortName>Inventories, net (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureInventoriesNetTables</ParentRole>
      <Position>51</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>40501 - Disclosure - Marketable securities - Schedule of Marketable Securities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureMarketableSecuritiesScheduleOfMarketableSecuritiesDetails</Role>
      <ShortName>Marketable securities - Schedule of Marketable Securities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>40601 - Disclosure - Other noncurrent assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentAssetsDetails</Role>
      <ShortName>Other noncurrent assets (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherNoncurrentAssetsTables</ParentRole>
      <Position>53</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>40701 - Disclosure - Long-term debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureLongTermDebtDetails</Role>
      <ShortName>Long-term debt (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.valhi.net/20210930/taxonomy/role/DisclosureLongTermDebtTables</ParentRole>
      <Position>54</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>40702 - Disclosure - Long-term debt - Valhi Contran Credit Facility - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureLongTermDebtValhiContranCreditFacilityAdditionalInformationDetails</Role>
      <ShortName>Long-term debt - Valhi Contran Credit Facility - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>40703 - Disclosure - Long-term debt - Kronos 9.50 Senior Secured Notes - Additional Information (Details)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.valhi.net/role/DisclosureLongTermDebtKronos950SeniorSecuredNotesAdditionalInformationDetails</Role>
      <ShortName>Long-term debt - Kronos 9.50 Senior Secured Notes - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>40704 - Disclosure - Long-term debt - Revolving Credit Facility - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureLongTermDebtRevolvingCreditFacilityAdditionalInformationDetails</Role>
      <ShortName>Long-term debt - Revolving Credit Facility - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>40801 - Disclosure - Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureAccountsPayableAndAccruedLiabilitiesScheduleOfAccountsPayableAndAccruedLiabilitiesDetails</Role>
      <ShortName>Accounts payable and accrued liabilities - Schedule of Accounts Payable and Accrued Liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>40901 - Disclosure - Other noncurrent liabilities - Other noncurrent liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureOtherNoncurrentLiabilitiesOtherNoncurrentLiabilitiesDetails</Role>
      <ShortName>Other noncurrent liabilities - Other noncurrent liabilities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>41001 - Disclosure - Revenue - disaggregation of sales - Schedule of Disaggregates of Net Sales of our Chemicals Segment (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureRevenueDisaggregationOfSalesScheduleOfDisaggregatesOfNetSalesOfOurChemicalsSegmentDetail</Role>
      <ShortName>Revenue - disaggregation of sales - Schedule of Disaggregates of Net Sales of our Chemicals Segment (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>41002 - Disclosure - Revenue - disaggregation of sales - Schedule of Disaggregates of Net Sales of our Component Products and Real Estate Management and Development Segments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureRevenueDisaggregationOfSalesScheduleOfDisaggregatesOfNetSalesOfOurComponentProductsAndRealEstateManagementAndDevelopmentSegmentsDetails</Role>
      <ShortName>Revenue - disaggregation of sales - Schedule of Disaggregates of Net Sales of our Component Products and Real Estate Management and Development Segments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>41101 - Disclosure - Defined benefit pension plans - Components of Net Periodic Defined Benefit Pension Benefit Cost (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureDefinedBenefitPensionPlansComponentsOfNetPeriodicDefinedBenefitPensionBenefitCostDetails</Role>
      <ShortName>Defined benefit pension plans - Components of Net Periodic Defined Benefit Pension Benefit Cost (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>41201 - Disclosure - Other income, net - Schedule of Components of Other Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureOtherIncomeNetScheduleOfComponentsOfOtherIncomeDetails</Role>
      <ShortName>Other income, net - Schedule of Components of Other Income (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>41301 - Disclosure - Income Taxes - Provision for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureIncomeTaxesProvisionForIncomeTaxesDetails</Role>
      <ShortName>Income Taxes - Provision for Income Taxes (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>41401 - Disclosure - Noncontrolling interest in subsidiaries - Noncontrolling Interest in Net Assets of Subsidiaries (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureNoncontrollingInterestInSubsidiariesNoncontrollingInterestInNetAssetsOfSubsidiariesDetails</Role>
      <ShortName>Noncontrolling interest in subsidiaries - Noncontrolling Interest in Net Assets of Subsidiaries (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>41402 - Disclosure - Noncontrolling interest in subsidiaries - Schedule of Noncontrolling Interest in Net Income of Subsidiaries (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureNoncontrollingInterestInSubsidiariesScheduleOfNoncontrollingInterestInNetIncomeOfSubsidiariesDetails</Role>
      <ShortName>Noncontrolling interest in subsidiaries - Schedule of Noncontrolling Interest in Net Income of Subsidiaries (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>41501 - Disclosure - Stockholders' equity - Accumulated Other Comprehensive Loss (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureStockholdersEquityAccumulatedOtherComprehensiveLossDetails</Role>
      <ShortName>Stockholders' equity - Accumulated Other Comprehensive Loss (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>41601 - Disclosure - Commitments and contingencies - Changes in Accrued Environmental Remediation and Related Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureCommitmentsAndContingenciesChangesInAccruedEnvironmentalRemediationAndRelatedCostsDetails</Role>
      <ShortName>Commitments and contingencies - Changes in Accrued Environmental Remediation and Related Costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>41701 - Disclosure - Fair value measurements and financial instruments - Financial Instruments Recorded at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureFairValueMeasurementsAndFinancialInstrumentsFinancialInstrumentsRecordedAtFairValueDetails</Role>
      <ShortName>Fair value measurements and financial instruments - Financial Instruments Recorded at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>41702 - Disclosure - Fair value measurements and financial instruments - Financial Instruments not Carried at Fair Value (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureFairValueMeasurementsAndFinancialInstrumentsFinancialInstrumentsNotCarriedAtFairValueDetails</Role>
      <ShortName>Fair value measurements and financial instruments - Financial Instruments not Carried at Fair Value (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>41703 - Disclosure - Fair value measurements and financial instruments - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/20210930/taxonomy/role/DisclosureFairValueMeasurementsAndFinancialInstrumentsAdditionalInformationDetails</Role>
      <ShortName>Fair value measurements and financial instruments - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="vhl-20260331x10q.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>41801 - Disclosure - Restructuring costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.valhi.net/role/DisclosureRestructuringCostsDetails</Role>
      <ShortName>Restructuring costs (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.valhi.net/role/DisclosureRestructuringCostsTables</ParentRole>
      <Position>72</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>vhl-20260331.xsd</File>
    <File>vhl-20260331_cal.xml</File>
    <File>vhl-20260331_def.xml</File>
    <File>vhl-20260331_lab.xml</File>
    <File>vhl-20260331_pre.xml</File>
    <File doctype="10-Q" isDefinitelyFs="true" isUsgaap="true" original="vhl-20260331x10q.htm">vhl-20260331x10q.htm</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy items="622">http://fasb.org/us-gaap/2025</BaseTaxonomy>
    <BaseTaxonomy items="30">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
