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      <ShortName>Employee Benefits (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://smpcorp.com/role/EmployeeBenefitsTables</ParentRole>
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    <Report>
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      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>091100 - Disclosure - Fair Value Measurements (Details)</LongName>
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      <LongName>091200 - Disclosure - Earnings Per Share (Details)</LongName>
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      <LongName>091300 - Disclosure - Industry Segments (Details)</LongName>
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      <ShortName>Industry Segments (Details)</ShortName>
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      <LongName>091400 - Disclosure - Commitments and Contingencies (Details)</LongName>
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      <ShortName>All Reports</ShortName>
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  <Logs>
    <Log type="Warn">In ''Stock-Based Compensation Plans (Details)'', element us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 with value 4 months 24 days has label periodStartLabel, but the context is a duration, not an instant. It will be treated as if it had no label.</Log>
    <Log type="Warn">In ''Stock-Based Compensation Plans (Details)'', element us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 with value 4 months 24 days has label periodEndLabel, but the context is a duration, not an instant. It will be treated as if it had no label.</Log>
    <Log type="Warn">In ''Stock-Based Compensation Plans (Details)'', element us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 with value  has label periodStartLabel, but the context is a duration, not an instant. It will be treated as if it had no label.</Log>
    <Log type="Warn">In ''Stock-Based Compensation Plans (Details)'', element us-gaap:SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsOutstandingWeightedAverageRemainingContractualTerm2 with value  has label periodEndLabel, but the context is a duration, not an instant. It will be treated as if it had no label.</Log>
    <Log type="Info">In ''CONSOLIDATED BALANCE SHEETS (Unaudited)'', column(s) 2, 4, 5 are contained in other reports, so were removed by flow through suppression.</Log>
    <Log type="Info">In ''CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited)'', column(s) 1, 2 are contained in other reports, so were removed by flow through suppression.</Log>
  </Logs>
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    <File>smp-20150630_cal.xml</File>
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    <File>smp-20150630.xsd</File>
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  <SupplementalFiles/>
  <BaseTaxonomies/>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>

