<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>205</ContextCount>
  <ElementCount>94</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>133</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>000001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>020000 - Document - Risk/Return Summary {Unlabeled} - SIMT Large Cap Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLargeCapFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Large Cap Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>020006 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Large Cap Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLargeCapFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Large Cap Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>020007 - Document - Risk/Return Summary {Unlabeled} - SIMT LARGE CAP VALUE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLARGECAPVALUEFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT LARGE CAP VALUE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>020013 - Disclosure - Risk/Return Detail Data {Elements} - SIMT LARGE CAP VALUE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLARGECAPVALUEFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT LARGE CAP VALUE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>020014 - Document - Risk/Return Summary {Unlabeled} - SIMT LARGE CAP GROWTH FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLARGECAPGROWTHFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT LARGE CAP GROWTH FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>020020 - Disclosure - Risk/Return Detail Data {Elements} - SIMT LARGE CAP GROWTH FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLARGECAPGROWTHFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT LARGE CAP GROWTH FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>020021 - Document - Risk/Return Summary {Unlabeled} - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTTAXMANAGEDLARGECAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>020027 - Disclosure - Risk/Return Detail Data {Elements} - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTTAXMANAGEDLARGECAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>020028 - Document - Risk/Return Summary {Unlabeled} - SIMT S&amp;P 500 Index Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSP500IndexFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT S&amp;P 500 Index Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>020034 - Disclosure - Risk/Return Detail Data {Elements} - SIMT S&amp;P 500 Index Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSP500IndexFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT S&amp;P 500 Index Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>020035 - Document - Risk/Return Summary {Unlabeled} - SIMT Small Cap Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSmallCapFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Small Cap Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>020041 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Small Cap Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSmallCapFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Small Cap Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>020042 - Document - Risk/Return Summary {Unlabeled} - SIMT SMALL CAP VALUE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSMALLCAPVALUEFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT SMALL CAP VALUE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>020048 - Disclosure - Risk/Return Detail Data {Elements} - SIMT SMALL CAP VALUE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSMALLCAPVALUEFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT SMALL CAP VALUE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>020049 - Document - Risk/Return Summary {Unlabeled} - SIMT SMALL CAP GROWTH FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSMALLCAPGROWTHFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT SMALL CAP GROWTH FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>020055 - Disclosure - Risk/Return Detail Data {Elements} - SIMT SMALL CAP GROWTH FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSMALLCAPGROWTHFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT SMALL CAP GROWTH FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>020056 - Document - Risk/Return Summary {Unlabeled} - SIMT TAX-MANAGED SMALL/MID CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTTAXMANAGEDSMALLMIDCAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT TAX-MANAGED SMALL/MID CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>020062 - Disclosure - Risk/Return Detail Data {Elements} - SIMT TAX-MANAGED SMALL/MID CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTTAXMANAGEDSMALLMIDCAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT TAX-MANAGED SMALL/MID CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>020063 - Document - Risk/Return Summary {Unlabeled} - SIMT MID CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMIDCAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT MID CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>020069 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MID CAP FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMIDCAPFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MID CAP FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>020070 - Document - Risk/Return Summary {Unlabeled} - SIMT US MANAGED VOLATILITY FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTUSMANAGEDVOLATILITYFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT US MANAGED VOLATILITY FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>020076 - Disclosure - Risk/Return Detail Data {Elements} - SIMT US MANAGED VOLATILITY FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTUSMANAGEDVOLATILITYFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT US MANAGED VOLATILITY FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>020077 - Document - Risk/Return Summary {Unlabeled} - SIMT GLOBAL MANAGED VOLATILITY FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTGLOBALMANAGEDVOLATILITYFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT GLOBAL MANAGED VOLATILITY FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>020083 - Disclosure - Risk/Return Detail Data {Elements} - SIMT GLOBAL MANAGED VOLATILITY FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTGLOBALMANAGEDVOLATILITYFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT GLOBAL MANAGED VOLATILITY FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>020084 - Document - Risk/Return Summary {Unlabeled} - SIMT Tax-Managed Managed Volatility Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTTaxManagedManagedVolatilityFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Tax-Managed Managed Volatility Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>020090 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Tax-Managed Managed Volatility Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTTaxManagedManagedVolatilityFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Tax-Managed Managed Volatility Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>020091 - Document - Risk/Return Summary {Unlabeled} - SIMT REAL ESTATE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTREALESTATEFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT REAL ESTATE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>020097 - Disclosure - Risk/Return Detail Data {Elements} - SIMT REAL ESTATE FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTREALESTATEFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT REAL ESTATE FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>020098 - Document - Risk/Return Summary {Unlabeled} - SIMT Enhanced Income Fund - Class A (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTEnhancedIncomeFundClassAClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Enhanced Income Fund - Class A (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>020104 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Enhanced Income Fund - Class A (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTEnhancedIncomeFundClassAClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Enhanced Income Fund - Class A (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>020105 - Document - Risk/Return Summary {Unlabeled} - SIMT CORE FIXED INCOME FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTCOREFIXEDINCOMEFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT CORE FIXED INCOME FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>020111 - Disclosure - Risk/Return Detail Data {Elements} - SIMT CORE FIXED INCOME FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTCOREFIXEDINCOMEFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT CORE FIXED INCOME FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>020112 - Document - Risk/Return Summary {Unlabeled} - SIMT U.S. Fixed Income Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTUSFixedIncomeFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT U.S. Fixed Income Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>020118 - Disclosure - Risk/Return Detail Data {Elements} - SIMT U.S. Fixed Income Fund (- Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTUSFixedIncomeFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT U.S. Fixed Income Fund (- Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>020119 - Document - Risk/Return Summary {Unlabeled} - SIMT HIGH YIELD BOND FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTHIGHYIELDBONDFUNDCLASSA</Role>
      <ShortName>Risk/Return Summary  - SIMT HIGH YIELD BOND FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>020125 - Disclosure - Risk/Return Detail Data {Elements} - SIMT HIGH YIELD BOND FUND (- CLASS A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTHIGHYIELDBONDFUNDCLASSA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT HIGH YIELD BOND FUND (- CLASS A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>020126 - Document - Risk/Return Summary {Unlabeled} - SIMT Real Return Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTRealReturnFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Real Return Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>020132 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Real Return Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTRealReturnFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Real Return Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>020133 - Document - Risk/Return Summary {Unlabeled} - SIMT Multi-Strategy Alternative Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMultiStrategyAlternativeFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Multi-Strategy Alternative Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>020139 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Multi-Strategy Alternative Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMultiStrategyAlternativeFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Multi-Strategy Alternative Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>020140 - Document - Risk/Return Summary {Unlabeled} - SIMT Large Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLargeCapFundClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT Large Cap Fund (- Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R148.htm</HtmlFileName>
      <LongName>020146 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Large Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLargeCapFundClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Large Cap Fund (- Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R149.htm</HtmlFileName>
      <LongName>020147 - Document - Risk/Return Summary {Unlabeled} - SIMT LARGE CAP VALUE FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLARGECAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT LARGE CAP VALUE FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R155.htm</HtmlFileName>
      <LongName>020153 - Disclosure - Risk/Return Detail Data {Elements} - SIMT LARGE CAP VALUE FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLARGECAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT LARGE CAP VALUE FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R156.htm</HtmlFileName>
      <LongName>020154 - Document - Risk/Return Summary {Unlabeled} - SIMT LARGE CAP GROWTH FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTLARGECAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT LARGE CAP GROWTH FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R162.htm</HtmlFileName>
      <LongName>020160 - Disclosure - Risk/Return Detail Data {Elements} - SIMT LARGE CAP GROWTH FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTLARGECAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT LARGE CAP GROWTH FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R163.htm</HtmlFileName>
      <LongName>020161 - Document - Risk/Return Summary {Unlabeled} - SIMT S&amp;P 500 Index Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSP500IndexFundClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT S&amp;P 500 Index Fund (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R169.htm</HtmlFileName>
      <LongName>020167 - Disclosure - Risk/Return Detail Data {Elements} - SIMT S&amp;P 500 Index Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSP500IndexFundClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT S&amp;P 500 Index Fund (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R170.htm</HtmlFileName>
      <LongName>020168 - Document - Risk/Return Summary {Unlabeled} - SIMT Small Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSmallCapFundClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT Small Cap Fund (- Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R176.htm</HtmlFileName>
      <LongName>020174 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Small Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSmallCapFundClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Small Cap Fund (- Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R177.htm</HtmlFileName>
      <LongName>020175 - Document - Risk/Return Summary {Unlabeled} - SIMT SMALL CAP VALUE FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSMALLCAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT SMALL CAP VALUE FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R183.htm</HtmlFileName>
      <LongName>020181 - Disclosure - Risk/Return Detail Data {Elements} - SIMT SMALL CAP VALUE FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSMALLCAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT SMALL CAP VALUE FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R184.htm</HtmlFileName>
      <LongName>020182 - Document - Risk/Return Summary {Unlabeled} - SIMT SMALL CAP GROWTH FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSMALLCAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT SMALL CAP GROWTH FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R190.htm</HtmlFileName>
      <LongName>020188 - Disclosure - Risk/Return Detail Data {Elements} - SIMT SMALL CAP GROWTH FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSMALLCAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT SMALL CAP GROWTH FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R191.htm</HtmlFileName>
      <LongName>020189 - Document - Risk/Return Summary {Unlabeled} - SIMT MID CAP FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMIDCAPFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT MID CAP FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R197.htm</HtmlFileName>
      <LongName>020195 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MID CAP FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMIDCAPFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MID CAP FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R198.htm</HtmlFileName>
      <LongName>020196 - Document - Risk/Return Summary {Unlabeled} - SIMT US MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTUSMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT US MANAGED VOLATILITY FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R204.htm</HtmlFileName>
      <LongName>020202 - Disclosure - Risk/Return Detail Data {Elements} - SIMT US MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTUSMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT US MANAGED VOLATILITY FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R205.htm</HtmlFileName>
      <LongName>020203 - Document - Risk/Return Summary {Unlabeled} - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTGLOBALMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R211.htm</HtmlFileName>
      <LongName>020209 - Disclosure - Risk/Return Detail Data {Elements} - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTGLOBALMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R212.htm</HtmlFileName>
      <LongName>020210 - Document - Risk/Return Summary {Unlabeled} - SIMT REAL ESTATE FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTREALESTATEFUNDClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT REAL ESTATE FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R218.htm</HtmlFileName>
      <LongName>020216 - Disclosure - Risk/Return Detail Data {Elements} - SIMT REAL ESTATE FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTREALESTATEFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT REAL ESTATE FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R219.htm</HtmlFileName>
      <LongName>020217 - Document - Risk/Return Summary {Unlabeled} - SIMT ENHANCED INCOME FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTENHANCEDINCOMEFUNDClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT ENHANCED INCOME FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R225.htm</HtmlFileName>
      <LongName>020223 - Disclosure - Risk/Return Detail Data {Elements} - SIMT ENHANCED INCOME FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTENHANCEDINCOMEFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT ENHANCED INCOME FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R226.htm</HtmlFileName>
      <LongName>020224 - Document - Risk/Return Summary {Unlabeled} - SIMT CORE FIXED INCOME FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTCOREFIXEDINCOMEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary  - SIMT CORE FIXED INCOME FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R232.htm</HtmlFileName>
      <LongName>020230 - Disclosure - Risk/Return Detail Data {Elements} - SIMT CORE FIXED INCOME FUND (- CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTCOREFIXEDINCOMEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT CORE FIXED INCOME FUND (- CLASS I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R233.htm</HtmlFileName>
      <LongName>020231 - Document - Risk/Return Summary {Unlabeled} - SIMT U.S. Fixed Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTUSFixedIncomeFund</Role>
      <ShortName>Risk/Return Summary  - SIMT U.S. Fixed Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R239.htm</HtmlFileName>
      <LongName>020237 - Disclosure - Risk/Return Detail Data {Elements} - SIMT U.S. Fixed Income Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTUSFixedIncomeFund</Role>
      <ShortName>Risk/Return Detail Data  - SIMT U.S. Fixed Income Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R240.htm</HtmlFileName>
      <LongName>020238 - Document - Risk/Return Summary {Unlabeled} - SIMT HIGH YIELD BOND FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTHIGHYIELDBONDFUNDClassI</Role>
      <ShortName>Risk/Return Summary  - SIMT HIGH YIELD BOND FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R246.htm</HtmlFileName>
      <LongName>020244 - Disclosure - Risk/Return Detail Data {Elements} - SIMT HIGH YIELD BOND FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTHIGHYIELDBONDFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data  - SIMT HIGH YIELD BOND FUND (Class I)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R247.htm</HtmlFileName>
      <LongName>020245 - Document - Risk/Return Summary {Unlabeled} - SIMT Real Return Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTRealReturnFund</Role>
      <ShortName>Risk/Return Summary  - SIMT Real Return Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R253.htm</HtmlFileName>
      <LongName>020251 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Real Return Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTRealReturnFund</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Real Return Fund</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R254.htm</HtmlFileName>
      <LongName>020252 - Document - Risk/Return Summary {Unlabeled} - SIMT S&amp;P 500 Index Fund (Class E)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTSP500IndexFundClassE</Role>
      <ShortName>Risk/Return Summary  - SIMT S&amp;P 500 Index Fund (Class E)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R260.htm</HtmlFileName>
      <LongName>020258 - Disclosure - Risk/Return Detail Data {Elements} - SIMT S&amp;P 500 Index Fund (Class E)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTSP500IndexFundClassE</Role>
      <ShortName>Risk/Return Detail Data  - SIMT S&amp;P 500 Index Fund (Class E)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R261.htm</HtmlFileName>
      <LongName>020259 - Document - Risk/Return Summary {Unlabeled} - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTTAXMANAGEDLARGECAPFUNDCLASSY</Role>
      <ShortName>Risk/Return Summary  - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS Y)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R267.htm</HtmlFileName>
      <LongName>020265 - Disclosure - Risk/Return Detail Data {Elements} - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTTAXMANAGEDLARGECAPFUNDCLASSY</Role>
      <ShortName>Risk/Return Detail Data  - SIMT TAX-MANAGED LARGE CAP FUND (- CLASS Y)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R268.htm</HtmlFileName>
      <LongName>020266 - Document - Risk/Return Summary {Unlabeled} - SIMT Prime Obligation Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTPrimeObligationFundClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT Prime Obligation Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R271.htm</HtmlFileName>
      <LongName>020269 - Disclosure - Risk/Return Detail Data {Elements} - SIMT Prime Obligation Fund (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTPrimeObligationFundClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT Prime Obligation Fund (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R272.htm</HtmlFileName>
      <LongName>020270 - Document - Risk/Return Summary {Unlabeled} - SIMT MULTI-ASSET ACCUMULATION FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMULTIASSETACCUMULATIONFUNDClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT MULTI-ASSET ACCUMULATION FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R276.htm</HtmlFileName>
      <LongName>020274 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MULTI-ASSET ACCUMULATION FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMULTIASSETACCUMULATIONFUNDClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MULTI-ASSET ACCUMULATION FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R277.htm</HtmlFileName>
      <LongName>020275 - Document - Risk/Return Summary {Unlabeled} - SIMT MULTI-ASSET INCOME FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMULTIASSETINCOMEFUNDClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT MULTI-ASSET INCOME FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R281.htm</HtmlFileName>
      <LongName>020279 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MULTI-ASSET INCOME FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMULTIASSETINCOMEFUNDClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MULTI-ASSET INCOME FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R282.htm</HtmlFileName>
      <LongName>020280 - Document - Risk/Return Summary {Unlabeled} - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMULTIASSETINFLATIONMANAGEDFUNDClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R286.htm</HtmlFileName>
      <LongName>020284 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMULTIASSETINFLATIONMANAGEDFUNDClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>true</HasEmbeddedReports>
      <HtmlFileName>R287.htm</HtmlFileName>
      <LongName>020285 - Document - Risk/Return Summary {Unlabeled} - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DocumentRiskReturnSummaryUnlabeledSIMTMULTIASSETCAPITALSTABILITYFUNDClassA</Role>
      <ShortName>Risk/Return Summary  - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R291.htm</HtmlFileName>
      <LongName>020289 - Disclosure - Risk/Return Detail Data {Elements} - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class A)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://seic.com/20130128/role/DisclosureRiskReturnDetailDataElementsSIMTMULTIASSETCAPITALSTABILITYFUNDClassA</Role>
      <ShortName>Risk/Return Detail Data  - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class A)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R292.htm</HtmlFileName>
      <LongName>040000 - Disclosure - Risk/Return Detail Data {Elements}</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturnDetailData</Role>
      <ShortName>Risk/Return Detail Data</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs />
  <InputFiles>
    <File>ck0000804239-20130128.xml</File>
    <File>ck0000804239-20130128.xsd</File>
    <File>ck0000804239-20130128_cal.xml</File>
    <File>ck0000804239-20130128_def.xml</File>
    <File>ck0000804239-20130128_lab.xml</File>
    <File>ck0000804239-20130128_pre.xml</File>
  </InputFiles>
  <SupplementalFiles>
    <File>BarChart1.jpg</File>
    <File>BarChart2.jpg</File>
    <File>BarChart3.jpg</File>
    <File>BarChart4.jpg</File>
    <File>BarChart5.jpg</File>
    <File>BarChart6.jpg</File>
    <File>BarChart7.jpg</File>
    <File>BarChart8.jpg</File>
    <File>BarChart9.jpg</File>
    <File>BarChart10.jpg</File>
    <File>BarChart11.jpg</File>
    <File>BarChart12.jpg</File>
    <File>BarChart13.jpg</File>
    <File>BarChart14.jpg</File>
    <File>BarChart15.jpg</File>
    <File>BarChart16.jpg</File>
    <File>BarChart17.jpg</File>
    <File>BarChart18.jpg</File>
    <File>BarChart19.jpg</File>
    <File>BarChart20.jpg</File>
    <File>BarChart21.jpg</File>
    <File>BarChart22.jpg</File>
    <File>BarChart23.jpg</File>
    <File>BarChart24.jpg</File>
    <File>BarChart25.jpg</File>
    <File>BarChart26.jpg</File>
    <File>BarChart27.jpg</File>
    <File>BarChart28.jpg</File>
    <File>BarChart29.jpg</File>
    <File>BarChart30.jpg</File>
    <File>BarChart31.jpg</File>
    <File>BarChart32.jpg</File>
    <File>BarChart33.jpg</File>
    <File>BarChart34.jpg</File>
    <File>BarChart35.jpg</File>
    <File>BarChart36.jpg</File>
    <File>BarChart37.jpg</File>
    <File>BarChart38.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
