<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <Version>2.4.1.9</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>255</ContextCount>
  <ElementCount>413</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>70</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>10</UnitCount>
  <MyReports>
    <Report>
      <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>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - CONSOLIDATED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedStatementsOfEarningsAndComprehensiveEarnings</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1002000 - Statement - CONSOLIDATED BALANCE SHEETS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1002501 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>CONSOLIDATED BALANCE SHEETS (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>CONSOLIDATED STATEMENTS OF CASH FLOWS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1004000 - Statement - CONSOLIDATED STATEMENT OF EQUITY</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedStatementOfEquity</Role>
      <ShortName>CONSOLIDATED STATEMENT OF EQUITY</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1004001 - Statement - CONSOLIDATED STATEMENT OF EQUITY (PARENTHETICAL)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ConsolidatedStatementOfEquityParenthetical</Role>
      <ShortName>CONSOLIDATED STATEMENT OF EQUITY (PARENTHETICAL)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - General</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/General</Role>
      <ShortName>General</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Restrictions on cash and investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/RestrictionsOnCashAndInvestments</Role>
      <ShortName>Restrictions on cash and investments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2103100 - Disclosure - Statutory Surplus and Dividend restrictions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/StatutorySurplusAndDividendRestrictions</Role>
      <ShortName>Statutory Surplus and Dividend restrictions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - Investments in debt and equity securities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecurities</Role>
      <ShortName>Investments in debt and equity securities</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - Fair value measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurements</Role>
      <ShortName>Fair value measurements</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Investment income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentIncome</Role>
      <ShortName>Investment income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Income taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxes</Role>
      <ShortName>Income taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - Goodwill and acquired intangibles</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GoodwillAndAcquiredIntangibles</Role>
      <ShortName>Goodwill and acquired intangibles</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2116100 - Disclosure - Equity investees</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EquityInvestees</Role>
      <ShortName>Equity investees</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2120100 - Disclosure - Notes payable, convertible senior notes and line of credit</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.stewart.com/role/NotesPayableConvertibleSeniorNotesAndLineOfCredit</Role>
      <ShortName>Notes payable, convertible senior notes and line of credit</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2121100 - Disclosure - Estimated title losses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EstimatedTitleLosses</Role>
      <ShortName>Estimated title losses</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2122100 - Disclosure - Common Stock and Class B Common Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CommonStockAndClassBCommonStock</Role>
      <ShortName>Common Stock and Class B Common Stock</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2123100 - Disclosure - Share-based incentives</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ShareBasedIncentives</Role>
      <ShortName>Share-based incentives</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2124100 - Disclosure - Earnings per share</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShare</Role>
      <ShortName>Earnings per share</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2125100 - Disclosure - Reinsurance</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/Reinsurance</Role>
      <ShortName>Reinsurance</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2127100 - Disclosure - Leases</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/Leases</Role>
      <ShortName>Leases</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2128100 - Disclosure - Contingent liabilities and commitments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ContingentLiabilitiesAndCommitments</Role>
      <ShortName>Contingent liabilities and commitments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2130100 - Disclosure - Regulatory and legal developments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/RegulatoryAndLegalDevelopments</Role>
      <ShortName>Regulatory and legal developments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2131100 - Disclosure - Segment information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformation</Role>
      <ShortName>Segment information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2132100 - Disclosure - Acquisitions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/Acquisitions</Role>
      <ShortName>Acquisitions</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2133100 - Disclosure - Other comprehensive earnings (loss)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveEarningsLoss</Role>
      <ShortName>Other comprehensive earnings (loss)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2141100 - Disclosure - Quarterly financial information (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/QuarterlyFinancialInformationUnaudited</Role>
      <ShortName>Quarterly financial information (unaudited)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2143100 - Disclosure - Schedule I - Parent Company Financial Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIParentCompanyFinancialInformation</Role>
      <ShortName>Schedule I - Parent Company Financial Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2144100 - Disclosure - Schedule II - VALUATION AND QUALIFYING ACCOUNTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIiValuationAndQualifyingAccounts</Role>
      <ShortName>Schedule II - VALUATION AND QUALIFYING ACCOUNTS</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2201201 - Disclosure - General (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GeneralPolicies</Role>
      <ShortName>General (Policies)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2304301 - Disclosure - Investments in debt and equity securities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesTables</Role>
      <ShortName>Investments in debt and equity securities (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - Fair value measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair value measurements (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.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>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2311301 - Disclosure - Income taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesTables</Role>
      <ShortName>Income taxes (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2315301 - Disclosure - Goodwill and acquired intangibles (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GoodwillAndAcquiredIntangiblesTables</Role>
      <ShortName>Goodwill and acquired intangibles (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2316301 - Disclosure - Equity investees (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EquityInvesteesTables</Role>
      <ShortName>Equity investees (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2320301 - Disclosure - Notes payable, convertible senior notes and line of credit (Tables)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.stewart.com/role/NotesPayableConvertibleSeniorNotesAndLineOfCreditTables</Role>
      <ShortName>Notes payable, convertible senior notes and line of credit (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2321301 - Disclosure - Estimated title losses (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EstimatedTitleLossesTables</Role>
      <ShortName>Estimated title losses (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2324301 - Disclosure - Earnings per share (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShareTables</Role>
      <ShortName>Earnings per share (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2327301 - Disclosure - Leases (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/LeasesTables</Role>
      <ShortName>Leases (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2331301 - Disclosure - Segment information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationTables</Role>
      <ShortName>Segment information (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2333301 - Disclosure - Other comprehensive earnings (loss) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveEarningsLossTables</Role>
      <ShortName>Other comprehensive earnings (loss) (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2341301 - Disclosure - Quarterly financial information (unaudited) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/QuarterlyFinancialInformationUnauditedTables</Role>
      <ShortName>Quarterly financial information (unaudited) (Tables)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2401402 - Disclosure - General - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GeneralAdditionalInformationDetail</Role>
      <ShortName>General - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2402401 - Disclosure - Restrictions on cash and investments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/RestrictionsOnCashAndInvestmentsAdditionalInformationDetail</Role>
      <ShortName>Restrictions on cash and investments - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2403401 - Disclosure - Statutory Surplus and Dividend restrictions - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/StatutorySurplusAndDividendRestrictionsAdditionalInformationDetail</Role>
      <ShortName>Statutory Surplus and Dividend restrictions - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2404402 - Disclosure - Investments in debt and equity securities - Amortized Costs and Fair Values (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAmortizedCostsAndFairValuesDetail</Role>
      <ShortName>Investments in debt and equity securities - Amortized Costs and Fair Values (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2404403 - Disclosure - Investments in debt and equity securities - Gross Unrealized Gains and Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesGrossUnrealizedGainsAndLossesDetail</Role>
      <ShortName>Investments in debt and equity securities - Gross Unrealized Gains and Losses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2404404 - Disclosure - Investments in debt and equity securities - Debt Securities According Contractual Terms (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesDebtSecuritiesAccordingContractualTermsDetail</Role>
      <ShortName>Investments in debt and equity securities - Debt Securities According Contractual Terms (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2404405 - Disclosure - Investments in debt and equity securities - Gross Unrealized Losses on Investments and Fair Values of Related Securities (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesGrossUnrealizedLossesOnInvestmentsAndFairValuesOfRelatedSecuritiesDetail</Role>
      <ShortName>Investments in debt and equity securities - Gross Unrealized Losses on Investments and Fair Values of Related Securities (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2404406 - Disclosure - Investments in debt and equity securities - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/InvestmentsInDebtAndEquitySecuritiesAdditionalInformationDetail</Role>
      <ShortName>Investments in debt and equity securities - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - Fair value measurements - Financial Instrument Measured at Fair Value on Recurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsFinancialInstrumentMeasuredAtFairValueOnRecurringBasisDetail</Role>
      <ShortName>Fair value measurements - Financial Instrument Measured at Fair Value on Recurring Basis (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - Fair value measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsAssetsMeasuredAtFairValueOnNonrecurringBasisDetail</Role>
      <ShortName>Fair value measurements - Assets Measured at Fair Value on Nonrecurring Basis (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2406404 - Disclosure - Fair value measurements - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/FairValueMeasurementsAdditionalInformationDetail</Role>
      <ShortName>Fair value measurements - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.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>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.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>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - Income taxes - Income Tax Expense (Benefit) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesIncomeTaxExpenseBenefitDetail</Role>
      <ShortName>Income taxes - Income Tax Expense (Benefit) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2411403 - Disclosure - Income taxes - Reconciliation of Income Tax Expenses Computed at Federal Statutory Rate with Income Tax Expense (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesReconciliationOfIncomeTaxExpensesComputedAtFederalStatutoryRateWithIncomeTaxExpenseDetail</Role>
      <ShortName>Income taxes - Reconciliation of Income Tax Expenses Computed at Federal Statutory Rate with Income Tax Expense (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2411404 - Disclosure - Income taxes - Reconciliation of Income Tax Expenses Computed at Federal Statutory Rate with Income Tax Expense (Additional Information) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesReconciliationOfIncomeTaxExpensesComputedAtFederalStatutoryRateWithIncomeTaxExpenseAdditionalInformationDetail</Role>
      <ShortName>Income taxes - Reconciliation of Income Tax Expenses Computed at Federal Statutory Rate with Income Tax Expense (Additional Information) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2411405 - Disclosure - Income taxes - Deferred Income Taxes (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesDeferredIncomeTaxesDetail</Role>
      <ShortName>Income taxes - Deferred Income Taxes (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2411406 - Disclosure - Income taxes - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/IncomeTaxesAdditionalInformationDetail</Role>
      <ShortName>Income taxes - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2415402 - Disclosure - Goodwill and acquired intangibles - Summary of Goodwill (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GoodwillAndAcquiredIntangiblesSummaryOfGoodwillDetail</Role>
      <ShortName>Goodwill and acquired intangibles - Summary of Goodwill (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>2415403 - Disclosure - Goodwill and acquired intangibles - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/GoodwillAndAcquiredIntangiblesAdditionalInformationDetail</Role>
      <ShortName>Goodwill and acquired intangibles - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>2416402 - Disclosure - Equity investees - Summarized Aggregate Financial Information for Equity Investees (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EquityInvesteesSummarizedAggregateFinancialInformationForEquityInvesteesDetail</Role>
      <ShortName>Equity investees - Summarized Aggregate Financial Information for Equity Investees (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>2416403 - Disclosure - Equity investees - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EquityInvesteesAdditionalInformationDetail</Role>
      <ShortName>Equity investees - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>2420402 - Disclosure - Notes payable, convertible senior notes and line of credit - Summary of Notes Payable (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.stewart.com/role/NotesPayableConvertibleSeniorNotesAndLineOfCreditSummaryOfNotesPayableDetail</Role>
      <ShortName>Notes payable, convertible senior notes and line of credit - Summary of Notes Payable (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>2420403 - Disclosure - Notes payable, convertible senior notes and line of credit - Summary of Notes Payable (Additional Information) (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.stewart.com/role/NotesPayableConvertibleSeniorNotesAndLineOfCreditSummaryOfNotesPayableAdditionalInformationDetail</Role>
      <ShortName>Notes payable, convertible senior notes and line of credit - Summary of Notes Payable (Additional Information) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>2420404 - Disclosure - Notes payable, convertible senior notes and line of credit - Additional Information (Detail)</LongName>
      <ReportType>Notes</ReportType>
      <Role>http://www.stewart.com/role/NotesPayableConvertibleSeniorNotesAndLineOfCreditAdditionalInformationDetail</Role>
      <ShortName>Notes payable, convertible senior notes and line of credit - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>2421402 - Disclosure - Estimated title Losses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EstimatedTitleLossesDetail</Role>
      <ShortName>Estimated title Losses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>2421403 - Disclosure - Estimated title losses - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EstimatedTitleLossesAdditionalInformationDetail</Role>
      <ShortName>Estimated title losses - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>2422401 - Disclosure - Common Stock and Class B Common Stock - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/CommonStockAndClassBCommonStockAdditionalInformationDetail</Role>
      <ShortName>Common Stock and Class B Common Stock - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>2423401 - Disclosure - Share-based incentives - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ShareBasedIncentivesAdditionalInformationDetail</Role>
      <ShortName>Share-based incentives - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>2424402 - Disclosure - Earnings per share - Basic and Diluted Earnings Per Share (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/EarningsPerShareBasicAndDilutedEarningsPerShareDetail</Role>
      <ShortName>Earnings per share - Basic and Diluted Earnings Per Share (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>2425401 - Disclosure - Reinsurance - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ReinsuranceAdditionalInformationDetail</Role>
      <ShortName>Reinsurance - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>2427402 - Disclosure - Leases - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/LeasesAdditionalInformationDetail</Role>
      <ShortName>Leases - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>2427403 - Disclosure - Leases - Summary of Future Minimum Lease Payments (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/LeasesSummaryOfFutureMinimumLeasePaymentsDetail</Role>
      <ShortName>Leases - Summary of Future Minimum Lease Payments (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>2428401 - Disclosure - Contingent Liabilities and Commitments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ContingentLiabilitiesAndCommitmentsAdditionalInformationDetail</Role>
      <ShortName>Contingent Liabilities and Commitments - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>2430401 - Disclosure - Regulatory and Legal Developments - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/RegulatoryAndLegalDevelopmentsAdditionalInformationDetail</Role>
      <ShortName>Regulatory and Legal Developments - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>2431402 - 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>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>2431403 - Disclosure - Segment information - Summary of Segmental Revenues and Expenses (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationSummaryOfSegmentalRevenuesAndExpensesDetail</Role>
      <ShortName>Segment information - Summary of Segmental Revenues and Expenses (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>2431404 - Disclosure - Segment information - Revenues Generated in Domestic and Foreign Country (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/SegmentInformationRevenuesGeneratedInDomesticAndForeignCountryDetail</Role>
      <ShortName>Segment information - Revenues Generated in Domestic and Foreign Country (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>2432401 - Disclosure - Acquisitions - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/AcquisitionsAdditionalInformationDetails</Role>
      <ShortName>Acquisitions - Additional Information (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>2433402 - Disclosure - Other comprehensive earnings (loss) - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/OtherComprehensiveEarningsLossAdditionalInformationDetails</Role>
      <ShortName>Other comprehensive earnings (loss) - Additional Information (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>2441402 - Disclosure - Quarterly financial information (unaudited) - Revenues Financial Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/QuarterlyFinancialInformationUnauditedRevenuesFinancialInformationDetail</Role>
      <ShortName>Quarterly financial information (unaudited) - Revenues Financial Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>2443401 - Schedule - Schedule I - Statements of Operations and Retained Earnings (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIStatementsOfOperationsAndRetainedEarningsDetail</Role>
      <ShortName>Schedule I - Statements of Operations and Retained Earnings (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>2443402 - Schedule - Schedule I - Statements of Operations and Retained Earnings (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIStatementsOfOperationsAndRetainedEarningsParentheticalDetail</Role>
      <ShortName>Schedule I - Statements of Operations and Retained Earnings (Parenthetical) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>2443403 - Schedule - Schedule I - Balance Sheets (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIBalanceSheetsDetail</Role>
      <ShortName>Schedule I - Balance Sheets (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>2443404 - Schedule - Schedule I - Balance Sheets (Parenthetical) (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIBalanceSheetsParentheticalDetail</Role>
      <ShortName>Schedule I - Balance Sheets (Parenthetical) (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>2443405 - Schedule - Schedule I - Statements of Cash Flows (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIStatementsOfCashFlowsDetail</Role>
      <ShortName>Schedule I - Statements of Cash Flows (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>2443406 - Disclosure - Schedule I Parent Company - Additional Information (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIParentCompanyAdditionalInformationDetail</Role>
      <ShortName>Schedule I Parent Company - Additional Information (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>2444401 - Schedule - Schedule II - Valuation and Qualifying Accounts (Detail)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.stewart.com/role/ScheduleIiValuationAndQualifyingAccountsDetail</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts (Detail)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Element stc_LossContingencyAccrualProvisionIncreaseDecreaseInPriorYearEstimates had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_CashDividendsPaidToParentCompany had a mix of decimals attribute values: -3 0.</Log>
    <Log type="Info">Element us-gaap_CostMethodInvestmentsRealizedLosses had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_DeferredTaxLiabilities had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_EquityMethodInvestmentSummarizedFinancialInformationNetIncomeLoss had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_EquityMethodInvestmentSummarizedFinancialInformationRevenue had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_LossContingencyAccrualAtCarryingValue had a mix of decimals attribute values: -8 -3.</Log>
    <Log type="Info">Element us-gaap_LossContingencyAccrualProvision had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">'Monetary' elements on report '2401402 - Disclosure - General - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2403401 - Disclosure - Statutory Surplus and Dividend restrictions - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2411406 - Disclosure - Income taxes - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2420404 - Disclosure - Notes payable, convertible senior notes and line of credit - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2421403 - Disclosure - Estimated title losses - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2428401 - Disclosure - Contingent Liabilities and Commitments - Additional Information (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2432401 - Disclosure - Acquisitions - Additional Information (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '2443404 - Schedule - Schedule I - Balance Sheets (Parenthetical) (Detail)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '1/1/2013 - 3/31/2013' is shorter (89 days) and has only 3 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '4/1/2013 - 6/30/2013' is shorter (90 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '7/1/2013 - 9/30/2013' is shorter (91 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '10/1/2013 - 12/31/2013' is shorter (91 days) and has only 3 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '1/1/2014 - 3/31/2014' is shorter (89 days) and has only 3 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '4/1/2014 - 6/30/2014' is shorter (90 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '7/1/2014 - 9/30/2014' is shorter (91 days) and has only 1 values, so it is being removed.</Log>
    <Log type="Info">Columns in Cash Flows statement 'Schedule I - Statements of Cash Flows (Detail) (USD $)' have maximum duration 365 days and at least 47 values. Shorter duration columns must have at least one fourth (11) as many values. Column '10/1/2014 - 12/31/2014' is shorter (91 days) and has only 3 values, so it is being removed.</Log>
    <Log type="Info">Process Flow-Through: 1001000 - Statement - CONSOLIDATED STATEMENTS OF EARNINGS AND COMPREHENSIVE EARNINGS</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2014'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2013'</Log>
    <Log type="Info">Process Flow-Through: 1002000 - Statement - CONSOLIDATED BALANCE SHEETS</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">Process Flow-Through: 1002501 - Statement - CONSOLIDATED BALANCE SHEETS (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 1003000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
    <Log type="Info">Process Flow-Through: 1004001 - Statement - CONSOLIDATED STATEMENT OF EQUITY (PARENTHETICAL)</Log>
  </Logs>
  <InputFiles>
    <File>stc-20141231.xml</File>
    <File>stc-20141231.xsd</File>
    <File>stc-20141231_cal.xml</File>
    <File>stc-20141231_def.xml</File>
    <File>stc-20141231_lab.xml</File>
    <File>stc-20141231_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
