<?xml version='1.0' encoding='UTF-8'?>
<FilingSummary>
  <Version>3.5.0.2</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>124</ContextCount>
  <ElementCount>203</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>38</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (LOSS) (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedStatementsOfIncomeAndComprehensiveIncomeLossUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (LOSS) (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002000 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1002501 - Statement - CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003000 - Statement - CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedStatementsOfCashFlowsUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - CONDENSED CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedStatementOfEquityUnaudited</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1004001 - Statement - CONDENSED CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED) (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CondensedConsolidatedStatementOfEquityUnauditedParenthetical</Role>
      <ShortName>CONDENSED CONSOLIDATED STATEMENT OF EQUITY (UNAUDITED) (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Interim financial statements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InterimFinancialStatements</Role>
      <ShortName>Interim financial statements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Investments in debt and equity securities available-for-sale</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSale</Role>
      <ShortName>Investments in debt and equity securities available-for-sale</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - Fair value measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurements</Role>
      <ShortName>Fair value measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Investment income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncome</Role>
      <ShortName>Investment income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2112100 - Disclosure - Share-based incentives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ShareBasedIncentives</Role>
      <ShortName>Share-based incentives</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2113100 - Disclosure - Earnings per share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShare</Role>
      <ShortName>Earnings per share</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2114100 - Disclosure - Contingent liabilities and commitments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ContingentLiabilitiesAndCommitments</Role>
      <ShortName>Contingent liabilities and commitments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - Segment information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformation</Role>
      <ShortName>Segment information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2118100 - Disclosure - Regulatory and legal developments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/RegulatoryAndLegalDevelopments</Role>
      <ShortName>Regulatory and legal developments</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2119100 - Disclosure - Other comprehensive income (loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveIncomeLoss</Role>
      <ShortName>Other comprehensive income (loss)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2120100 - Disclosure - Exit activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ExitActivities</Role>
      <ShortName>Exit activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2121100 - Disclosure - Class B Common Stock conversion</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ClassBCommonStockConversion</Role>
      <ShortName>Class B Common Stock conversion</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2201201 - Disclosure - Interim financial statements (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InterimFinancialStatementsPolicies</Role>
      <ShortName>Interim financial statements (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2302301 - Disclosure - Investments in debt and equity securities available-for-sale (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleTables</Role>
      <ShortName>Investments in debt and equity securities available-for-sale (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSale</ParentRole>
      <Position>21</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2307301 - Disclosure - Fair value measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair value measurements (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/FairValueMeasurements</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - Investment income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncomeTables</Role>
      <ShortName>Investment income (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/InvestmentIncome</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2313301 - Disclosure - Earnings per share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings per share (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/EarningsPerShare</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2315301 - Disclosure - Segment information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationTables</Role>
      <ShortName>Segment information (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/SegmentInformation</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2319301 - Disclosure - Other comprehensive income (loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveIncomeLossTables</Role>
      <ShortName>Other comprehensive income (loss) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.stewart.com/role/OtherComprehensiveIncomeLoss</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2401402 - Disclosure - Interim financial statements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InterimFinancialStatementsDetail</Role>
      <ShortName>Interim financial statements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/InterimFinancialStatementsPolicies</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2402402 - Disclosure - Investments in debt and equity securities available-for-sale - Amortized Costs and Fair Values (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleAmortizedCostsAndFairValuesDetail</Role>
      <ShortName>Investments in debt and equity securities available-for-sale - Amortized Costs and Fair Values (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2402403 - Disclosure - Investments in debt and equity securities available-for-sale - Gross Unrealized Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleGrossUnrealizedGainsAndLossesDetail</Role>
      <ShortName>Investments in debt and equity securities available-for-sale - Gross Unrealized Gains and Losses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2402404 - Disclosure - Investments in debt and equity securities available-for-sale - Debt Securities According to Contractual Terms (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleDebtSecuritiesAccordingToContractualTermsDetail</Role>
      <ShortName>Investments in debt and equity securities available-for-sale - Debt Securities According to Contractual Terms (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2402405 - Disclosure - Investments in debt and equity securities available-for-sale - Gross Unrealized Losses on Investments and Fair Values of Related Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleGrossUnrealizedLossesOnInvestmentsAndFairValuesOfRelatedSecuritiesDetail</Role>
      <ShortName>Investments in debt and equity securities available-for-sale - Gross Unrealized Losses on Investments and Fair Values of Related Securities (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2402406 - Disclosure - Investments in debt and equity securities available-for-sale - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAvailableForSaleAdditionalInformationDetail</Role>
      <ShortName>Investments in debt and equity securities available-for-sale - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2407402 - Disclosure - Fair value measurements (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsDetail</Role>
      <ShortName>Fair value measurements (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/FairValueMeasurementsTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - Investment income - Gross Realized Investment and Other Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncomeGrossRealizedInvestmentAndOtherGainsAndLossesDetail</Role>
      <ShortName>Investment income - Gross Realized Investment and Other Gains and Losses (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Investment income - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncomeAdditionalInformationDetail</Role>
      <ShortName>Investment income - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2409404 - Disclosure - Investment income - Proceeds from the Sale of Investments Available-for-Sale (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncomeProceedsFromSaleOfInvestmentsAvailableForSaleDetail</Role>
      <ShortName>Investment income - Proceeds from the Sale of Investments Available-for-Sale (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2412401 - Disclosure - Share-based incentives (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ShareBasedIncentivesDetail</Role>
      <ShortName>Share-based incentives (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/ShareBasedIncentives</ParentRole>
      <Position>37</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2413402 - Disclosure - Earnings per share - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShareAdditionalInformationDetails</Role>
      <ShortName>Earnings per share - Additional Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2413403 - Disclosure - Earnings per share - Calculation of Basic and Diluted Earnings Per Share (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShareCalculationOfBasicAndDilutedEarningsPerShareDetails</Role>
      <ShortName>Earnings per share - Calculation of Basic and Diluted Earnings Per Share (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2414401 - Disclosure - Contingent liabilities and commitments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ContingentLiabilitiesAndCommitmentsDetail</Role>
      <ShortName>Contingent liabilities and commitments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/ContingentLiabilitiesAndCommitments</ParentRole>
      <Position>40</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2415402 - Disclosure - Segment information - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationAdditionalInformationDetail</Role>
      <ShortName>Segment information - Additional Information (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2415403 - Disclosure - Segment information - Selected Statement of Operations and Income (Loss) Information Related to Segments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationSelectedStatementOfOperationsAndIncomeLossInformationRelatedToSegmentsDetail</Role>
      <ShortName>Segment information - Selected Statement of Operations and Income (Loss) Information Related to Segments (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2415404 - Disclosure - Segment information - Revenues Generated in United States and All International Operations (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationRevenuesGeneratedInUnitedStatesAndAllInternationalOperationsDetail</Role>
      <ShortName>Segment information - Revenues Generated in United States and All International Operations (Detail)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2419402 - Disclosure - Other comprehensive income (loss) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveIncomeLossDetails</Role>
      <ShortName>Other comprehensive income (loss) (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/OtherComprehensiveIncomeLossTables</ParentRole>
      <Position>44</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2420401 - Disclosure - Exit activities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ExitActivitiesDetails</Role>
      <ShortName>Exit activities (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/ExitActivities</ParentRole>
      <Position>45</Position>
    </Report>
    <Report instance="stc-20160630.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2421401 - Disclosure - Class B Common Stock conversion (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ClassBCommonStockConversionDetails</Role>
      <ShortName>Class B Common Stock conversion (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.stewart.com/role/ClassBCommonStockConversion</ParentRole>
      <Position>46</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>stc-20160630.xml</File>
    <File>stc-20160630.xsd</File>
    <File>stc-20160630_cal.xml</File>
    <File>stc-20160630_def.xml</File>
    <File>stc-20160630_lab.xml</File>
    <File>stc-20160630_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
