<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.25.4</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>3611</ContextCount>
  <ElementCount>69</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>260</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>2</UnitCount>
  <MyReports>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>010000 - Disclosure - Form N-1A Cover</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/N1aCover</Role>
      <ShortName>Form N-1A Cover</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>010002 - Disclosure - Investment Objectives and Goals</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/RiskReturn</Role>
      <ShortName>Investment Objectives and Goals</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>010003 - Disclosure - Fees and Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/FeesAndExpenses</Role>
      <ShortName>Fees and Expenses</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>010004 - Disclosure - Investment Strategy</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/InvestmentStrategy</Role>
      <ShortName>Investment Strategy</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>010005 - Disclosure - Investment Risks</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/InvestmentRisks</Role>
      <ShortName>Investment Risks</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>010006 - Disclosure - Performance Management</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/PerformanceManagement</Role>
      <ShortName>Performance Management</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>020020 - Disclosure - Annual Fund Operating Expenses</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/OperatingExpensesData</Role>
      <ShortName>Annual Fund Operating Expenses</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>020030 - Disclosure - Expense Example</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/ExpenseExample</Role>
      <ShortName>Expense Example</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>020050 - Disclosure - Annual Total Returns</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/BarChartData</Role>
      <ShortName>Annual Total Returns</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>020060 - Disclosure - Average Annual Total Returns</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/rr/role/PerformanceTableData</Role>
      <ShortName>Average Annual Total Returns</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>020100 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP FUND - Class F Prospectus - SIMT Large Cap Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPFUNDClassFProspectusSIMTLargeCapFundClassF</Role>
      <ShortName>Risk/Return Summary- LARGE CAP FUND - Class F Prospectus - SIMT Large Cap Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>020101 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP FUND - Class F Prospectus - SIMT Large Cap Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPFUNDClassFProspectusSIMTLargeCapFundClassF</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP FUND - Class F Prospectus - SIMT Large Cap Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>020102 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP VALUE FUND - Class F Prospectus - SIMT LARGE CAP VALUE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPVALUEFUNDClassFProspectusSIMTLARGECAPVALUEFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- LARGE CAP VALUE FUND - Class F Prospectus - SIMT LARGE CAP VALUE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>020103 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP VALUE FUND - Class F Prospectus - SIMT LARGE CAP VALUE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPVALUEFUNDClassFProspectusSIMTLARGECAPVALUEFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP VALUE FUND - Class F Prospectus - SIMT LARGE CAP VALUE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>020104 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP GROWTH FUND - Class F Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPGROWTHFUNDClassFProspectusSIMTLARGECAPGROWTHFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- LARGE CAP GROWTH FUND - Class F Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>020105 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP GROWTH FUND - Class F Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPGROWTHFUNDClassFProspectusSIMTLARGECAPGROWTHFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP GROWTH FUND - Class F Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>020106 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP INDEX FUND - Class F Prospectus - SIMT Large Cap Index Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPINDEXFUNDClassFProspectusSIMTLargeCapIndexFund</Role>
      <ShortName>Risk/Return Summary- LARGE CAP INDEX FUND - Class F Prospectus - SIMT Large Cap Index Fund</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>020107 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP INDEX FUND - Class F Prospectus - SIMT Large Cap Index Fund</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPINDEXFUNDClassFProspectusSIMTLargeCapIndexFund</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP INDEX FUND - Class F Prospectus - SIMT Large Cap Index Fund</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>020108 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED LARGE CAP FUND - Class F Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDLARGECAPFUNDClassFProspectusSIMTTAXMANAGEDLARGECAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED LARGE CAP FUND - Class F Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>020109 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED LARGE CAP FUND - Class F Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDLARGECAPFUNDClassFProspectusSIMTTAXMANAGEDLARGECAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED LARGE CAP FUND - Class F Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>020110 - Document - Risk/Return Summary {Unlabeled} - S&amp;P 500 INDEX FUND - Class F Prospectus - SIMT S&amp;P 500 Index Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSP500INDEXFUNDClassFProspectusSIMTSP500IndexFundClassF</Role>
      <ShortName>Risk/Return Summary- S&amp;P 500 INDEX FUND - Class F Prospectus - SIMT S&amp;P 500 Index Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>020111 - Disclosure - Risk/Return Detail Data {Elements} - S&amp;P 500 INDEX FUND - Class F Prospectus - SIMT S&amp;P 500 Index Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSP500INDEXFUNDClassFProspectusSIMTSP500IndexFundClassF</Role>
      <ShortName>Risk/Return Detail Data- S&amp;P 500 INDEX FUND - Class F Prospectus - SIMT S&amp;P 500 Index Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>020112 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP FUND - Class F Prospectus - SIMT Small Cap Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPFUNDClassFProspectusSIMTSmallCapFundClassF</Role>
      <ShortName>Risk/Return Summary- SMALL CAP FUND - Class F Prospectus - SIMT Small Cap Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>020113 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP FUND - Class F Prospectus - SIMT Small Cap Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPFUNDClassFProspectusSIMTSmallCapFundClassF</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP FUND - Class F Prospectus - SIMT Small Cap Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>020114 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP VALUE FUND - Class F Prospectus - SIMT SMALL CAP VALUE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPVALUEFUNDClassFProspectusSIMTSMALLCAPVALUEFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- SMALL CAP VALUE FUND - Class F Prospectus - SIMT SMALL CAP VALUE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>020115 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP VALUE FUND - Class F Prospectus - SIMT SMALL CAP VALUE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPVALUEFUNDClassFProspectusSIMTSMALLCAPVALUEFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP VALUE FUND - Class F Prospectus - SIMT SMALL CAP VALUE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>020116 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP GROWTH FUND - Class F Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPGROWTHFUNDClassFProspectusSIMTSMALLCAPGROWTHFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- SMALL CAP GROWTH FUND - Class F Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>020117 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP GROWTH FUND - Class F Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPGROWTHFUNDClassFProspectusSIMTSMALLCAPGROWTHFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP GROWTH FUND - Class F Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>020118 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED SMALL/MID CAP FUND - Class F Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDSMALLMIDCAPFUNDClassFProspectusSIMTTAXMANAGEDSMALLMIDCAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED SMALL/MID CAP FUND - Class F Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>020119 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED SMALL/MID CAP FUND - Class F Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDSMALLMIDCAPFUNDClassFProspectusSIMTTAXMANAGEDSMALLMIDCAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED SMALL/MID CAP FUND - Class F Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>020120 - Document - Risk/Return Summary {Unlabeled} - MID-CAP FUND - Class F Prospectus - SIMT MID CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMIDCAPFUNDClassFProspectusSIMTMIDCAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- MID-CAP FUND - Class F Prospectus - SIMT MID CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>020121 - Disclosure - Risk/Return Detail Data {Elements} - MID-CAP FUND - Class F Prospectus - SIMT MID CAP FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMIDCAPFUNDClassFProspectusSIMTMIDCAPFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- MID-CAP FUND - Class F Prospectus - SIMT MID CAP FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>020122 - Document - Risk/Return Summary {Unlabeled} - U.S. MANAGED VOLATILITY FUND - Class F Prospectus - SIMT US MANAGED VOLATILITY FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledUSMANAGEDVOLATILITYFUNDClassFProspectusSIMTUSMANAGEDVOLATILITYFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- U.S. MANAGED VOLATILITY FUND - Class F Prospectus - SIMT US MANAGED VOLATILITY FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>020123 - Disclosure - Risk/Return Detail Data {Elements} - U.S. MANAGED VOLATILITY FUND - Class F Prospectus - SIMT US MANAGED VOLATILITY FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsUSMANAGEDVOLATILITYFUNDClassFProspectusSIMTUSMANAGEDVOLATILITYFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- U.S. MANAGED VOLATILITY FUND - Class F Prospectus - SIMT US MANAGED VOLATILITY FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>020124 - Document - Risk/Return Summary {Unlabeled} - GLOBAL MANAGED VOLATILITY FUND - Class F Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledGLOBALMANAGEDVOLATILITYFUNDClassFProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- GLOBAL MANAGED VOLATILITY FUND - Class F Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>020125 - Disclosure - Risk/Return Detail Data {Elements} - GLOBAL MANAGED VOLATILITY FUND - Class F Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsGLOBALMANAGEDVOLATILITYFUNDClassFProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- GLOBAL MANAGED VOLATILITY FUND - Class F Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>020126 - Document - Risk/Return Summary {Unlabeled} - Tax-Managed Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTaxManagedManagedVolatilityFundClassFProspectusSIMTTaxManagedManagedVolatilityFundClassF</Role>
      <ShortName>Risk/Return Summary- Tax-Managed Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>020127 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Managed Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTaxManagedManagedVolatilityFundClassFProspectusSIMTTaxManagedManagedVolatilityFundClassF</Role>
      <ShortName>Risk/Return Detail Data- Tax-Managed Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>020128 - Document - Risk/Return Summary {Unlabeled} - Tax-Managed International Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTaxManagedInternationalManagedVolatilityFundClassFProspectusSIMTTaxManagedInternationalManagedVolatilityFundClassF</Role>
      <ShortName>Risk/Return Summary- Tax-Managed International Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>020129 - Disclosure - Risk/Return Detail Data {Elements} - Tax-Managed International Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTaxManagedInternationalManagedVolatilityFundClassFProspectusSIMTTaxManagedInternationalManagedVolatilityFundClassF</Role>
      <ShortName>Risk/Return Detail Data- Tax-Managed International Managed Volatility Fund - Class F Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>020130 - Document - Risk/Return Summary {Unlabeled} - REAL ESTATE FUND - Class F Prospectus - SIMT REAL ESTATE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALESTATEFUNDClassFProspectusSIMTREALESTATEFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- REAL ESTATE FUND - Class F Prospectus - SIMT REAL ESTATE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>020131 - Disclosure - Risk/Return Detail Data {Elements} - REAL ESTATE FUND - Class F Prospectus - SIMT REAL ESTATE FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALESTATEFUNDClassFProspectusSIMTREALESTATEFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- REAL ESTATE FUND - Class F Prospectus - SIMT REAL ESTATE FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>020132 - Document - Risk/Return Summary {Unlabeled} - CORE FIXED INCOME FUND - Class F Prospectus - SIMT CORE FIXED INCOME FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledCOREFIXEDINCOMEFUNDClassFProspectusSIMTCOREFIXEDINCOMEFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- CORE FIXED INCOME FUND - Class F Prospectus - SIMT CORE FIXED INCOME FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>020133 - Disclosure - Risk/Return Detail Data {Elements} - CORE FIXED INCOME FUND - Class F Prospectus - SIMT CORE FIXED INCOME FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsCOREFIXEDINCOMEFUNDClassFProspectusSIMTCOREFIXEDINCOMEFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- CORE FIXED INCOME FUND - Class F Prospectus - SIMT CORE FIXED INCOME FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>020134 - Document - Risk/Return Summary {Unlabeled} - HIGH YIELD BOND FUND - Class F Prospectus - SIMT HIGH YIELD BOND FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledHIGHYIELDBONDFUNDClassFProspectusSIMTHIGHYIELDBONDFUNDCLASSF</Role>
      <ShortName>Risk/Return Summary- HIGH YIELD BOND FUND - Class F Prospectus - SIMT HIGH YIELD BOND FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>020135 - Disclosure - Risk/Return Detail Data {Elements} - HIGH YIELD BOND FUND - Class F Prospectus - SIMT HIGH YIELD BOND FUND (CLASS F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsHIGHYIELDBONDFUNDClassFProspectusSIMTHIGHYIELDBONDFUNDCLASSF</Role>
      <ShortName>Risk/Return Detail Data- HIGH YIELD BOND FUND - Class F Prospectus - SIMT HIGH YIELD BOND FUND (CLASS F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>020136 - Document - Risk/Return Summary {Unlabeled} - CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Conservative Income Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledCONSERVATIVEINCOMEFUNDClassFProspectusSIMTConservativeIncomeFundClassF</Role>
      <ShortName>Risk/Return Summary- CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Conservative Income Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>020137 - Disclosure - Risk/Return Detail Data {Elements} - CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Conservative Income Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsCONSERVATIVEINCOMEFUNDClassFProspectusSIMTConservativeIncomeFundClassF</Role>
      <ShortName>Risk/Return Detail Data- CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Conservative Income Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>020138 - Document - Risk/Return Summary {Unlabeled} - TAX-FREE CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Tax-Free Conservative Income Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXFREECONSERVATIVEINCOMEFUNDClassFProspectusSIMTTaxFreeConservativeIncomeFundClassF</Role>
      <ShortName>Risk/Return Summary- TAX-FREE CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Tax-Free Conservative Income Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>020139 - Disclosure - Risk/Return Detail Data {Elements} - TAX-FREE CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Tax-Free Conservative Income Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXFREECONSERVATIVEINCOMEFUNDClassFProspectusSIMTTaxFreeConservativeIncomeFundClassF</Role>
      <ShortName>Risk/Return Detail Data- TAX-FREE CONSERVATIVE INCOME FUND - Class F Prospectus - SIMT Tax-Free Conservative Income Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>020140 - Document - Risk/Return Summary {Unlabeled} - REAL RETURN FUND - Class F Prospectus - SIMT Real Return Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALRETURNFUNDClassFProspectusSIMTRealReturnFundClassF</Role>
      <ShortName>Risk/Return Summary- REAL RETURN FUND - Class F Prospectus - SIMT Real Return Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>020141 - Disclosure - Risk/Return Detail Data {Elements} - REAL RETURN FUND - Class F Prospectus - SIMT Real Return Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALRETURNFUNDClassFProspectusSIMTRealReturnFundClassF</Role>
      <ShortName>Risk/Return Detail Data- REAL RETURN FUND - Class F Prospectus - SIMT Real Return Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>020142 - Document - Risk/Return Summary {Unlabeled} - DYNAMIC ASSET ALLOCATION FUND - Class F Prospectus - SIMT Dynamic Asset Allocation Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledDYNAMICASSETALLOCATIONFUNDClassFProspectusSIMTDynamicAssetAllocationFundClassF</Role>
      <ShortName>Risk/Return Summary- DYNAMIC ASSET ALLOCATION FUND - Class F Prospectus - SIMT Dynamic Asset Allocation Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>020143 - Disclosure - Risk/Return Detail Data {Elements} - DYNAMIC ASSET ALLOCATION FUND - Class F Prospectus - SIMT Dynamic Asset Allocation Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsDYNAMICASSETALLOCATIONFUNDClassFProspectusSIMTDynamicAssetAllocationFundClassF</Role>
      <ShortName>Risk/Return Detail Data- DYNAMIC ASSET ALLOCATION FUND - Class F Prospectus - SIMT Dynamic Asset Allocation Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>020144 - Document - Risk/Return Summary {Unlabeled} - MULTI-STRATEGY ALTERNATIVE FUND - Class F Prospectus - SIMT Multi-Strategy Alternative Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTISTRATEGYALTERNATIVEFUNDClassFProspectusSIMTMultiStrategyAlternativeFundClassF</Role>
      <ShortName>Risk/Return Summary- MULTI-STRATEGY ALTERNATIVE FUND - Class F Prospectus - SIMT Multi-Strategy Alternative Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>020145 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-STRATEGY ALTERNATIVE FUND - Class F Prospectus - SIMT Multi-Strategy Alternative Fund (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTISTRATEGYALTERNATIVEFUNDClassFProspectusSIMTMultiStrategyAlternativeFundClassF</Role>
      <ShortName>Risk/Return Detail Data- MULTI-STRATEGY ALTERNATIVE FUND - Class F Prospectus - SIMT Multi-Strategy Alternative Fund (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>020146 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP FUND - Class I Prospectus - SIMT Large Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPFUNDClassIProspectusSIMTLargeCapFundClassI</Role>
      <ShortName>Risk/Return Summary- LARGE CAP FUND - Class I Prospectus - SIMT Large Cap Fund (- Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>020147 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP FUND - Class I Prospectus - SIMT Large Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPFUNDClassIProspectusSIMTLargeCapFundClassI</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP FUND - Class I Prospectus - SIMT Large Cap Fund (- Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>020148 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP VALUE FUND - Class I Prospectus - SIMT LARGE CAP VALUE FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPVALUEFUNDClassIProspectusSIMTLARGECAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- LARGE CAP VALUE FUND - Class I Prospectus - SIMT LARGE CAP VALUE FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>020149 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP VALUE FUND - Class I Prospectus - SIMT LARGE CAP VALUE FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPVALUEFUNDClassIProspectusSIMTLARGECAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP VALUE FUND - Class I Prospectus - SIMT LARGE CAP VALUE FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>020150 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP GROWTH FUND - Class I Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPGROWTHFUNDClassIProspectusSIMTLARGECAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- LARGE CAP GROWTH FUND - Class I Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>020151 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP GROWTH FUND - Class I Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPGROWTHFUNDClassIProspectusSIMTLARGECAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP GROWTH FUND - Class I Prospectus - SIMT LARGE CAP GROWTH FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>020152 - Document - Risk/Return Summary {Unlabeled} - S&amp;P 500 Index Fund - Class I Prospectus - SIMT S&amp;P 500 Index Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSP500IndexFundClassIProspectusSIMTSP500IndexFundClassI</Role>
      <ShortName>Risk/Return Summary- S&amp;P 500 Index Fund - Class I Prospectus - SIMT S&amp;P 500 Index Fund (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>020153 - Disclosure - Risk/Return Detail Data {Elements} - S&amp;P 500 Index Fund - Class I Prospectus - SIMT S&amp;P 500 Index Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSP500IndexFundClassIProspectusSIMTSP500IndexFundClassI</Role>
      <ShortName>Risk/Return Detail Data- S&amp;P 500 Index Fund - Class I Prospectus - SIMT S&amp;P 500 Index Fund (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>020154 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP FUND - Class I Prospectus - SIMT Small Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPFUNDClassIProspectusSIMTSmallCapFundClassI</Role>
      <ShortName>Risk/Return Summary- SMALL CAP FUND - Class I Prospectus - SIMT Small Cap Fund (- Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>020155 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP FUND - Class I Prospectus - SIMT Small Cap Fund (- Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPFUNDClassIProspectusSIMTSmallCapFundClassI</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP FUND - Class I Prospectus - SIMT Small Cap Fund (- Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>020156 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP VALUE FUND - Class I Prospectus - SIMT SMALL CAP VALUE FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPVALUEFUNDClassIProspectusSIMTSMALLCAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- SMALL CAP VALUE FUND - Class I Prospectus - SIMT SMALL CAP VALUE FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>020157 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP VALUE FUND - Class I Prospectus - SIMT SMALL CAP VALUE FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPVALUEFUNDClassIProspectusSIMTSMALLCAPVALUEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP VALUE FUND - Class I Prospectus - SIMT SMALL CAP VALUE FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>020158 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP GROWTH FUND - Class I Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPGROWTHFUNDClassIProspectusSIMTSMALLCAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- SMALL CAP GROWTH FUND - Class I Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>020159 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP GROWTH FUND - Class I Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPGROWTHFUNDClassIProspectusSIMTSMALLCAPGROWTHFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP GROWTH FUND - Class I Prospectus - SIMT SMALL CAP GROWTH FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>020160 - Document - Risk/Return Summary {Unlabeled} - MID-CAP FUND - Class I Prospectus - SIMT MID CAP FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMIDCAPFUNDClassIProspectusSIMTMIDCAPFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- MID-CAP FUND - Class I Prospectus - SIMT MID CAP FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>020161 - Disclosure - Risk/Return Detail Data {Elements} - MID-CAP FUND - Class I Prospectus - SIMT MID CAP FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMIDCAPFUNDClassIProspectusSIMTMIDCAPFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- MID-CAP FUND - Class I Prospectus - SIMT MID CAP FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>020162 - Document - Risk/Return Summary {Unlabeled} - U.S. MANAGED VOLATILITY FUND - Class I Prospectus - SIMT US MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledUSMANAGEDVOLATILITYFUNDClassIProspectusSIMTUSMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Summary- U.S. MANAGED VOLATILITY FUND - Class I Prospectus - SIMT US MANAGED VOLATILITY FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>020163 - Disclosure - Risk/Return Detail Data {Elements} - U.S. MANAGED VOLATILITY FUND - Class I Prospectus - SIMT US MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsUSMANAGEDVOLATILITYFUNDClassIProspectusSIMTUSMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data- U.S. MANAGED VOLATILITY FUND - Class I Prospectus - SIMT US MANAGED VOLATILITY FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>020164 - Document - Risk/Return Summary {Unlabeled} - GLOBAL MANAGED VOLATILITY FUND - Class I Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledGLOBALMANAGEDVOLATILITYFUNDClassIProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Summary- GLOBAL MANAGED VOLATILITY FUND - Class I Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>020165 - Disclosure - Risk/Return Detail Data {Elements} - GLOBAL MANAGED VOLATILITY FUND - Class I Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsGLOBALMANAGEDVOLATILITYFUNDClassIProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data- GLOBAL MANAGED VOLATILITY FUND - Class I Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>020166 - Document - Risk/Return Summary {Unlabeled} - REAL ESTATE FUND - Class I Prospectus - SIMT REAL ESTATE FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALESTATEFUNDClassIProspectusSIMTREALESTATEFUNDClassI</Role>
      <ShortName>Risk/Return Summary- REAL ESTATE FUND - Class I Prospectus - SIMT REAL ESTATE FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>020167 - Disclosure - Risk/Return Detail Data {Elements} - REAL ESTATE FUND - Class I Prospectus - SIMT REAL ESTATE FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALESTATEFUNDClassIProspectusSIMTREALESTATEFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data- REAL ESTATE FUND - Class I Prospectus - SIMT REAL ESTATE FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>020168 - Document - Risk/Return Summary {Unlabeled} - CORE FIXED INCOME FUND - Class I Prospectus - SIMT CORE FIXED INCOME FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledCOREFIXEDINCOMEFUNDClassIProspectusSIMTCOREFIXEDINCOMEFUNDCLASSI</Role>
      <ShortName>Risk/Return Summary- CORE FIXED INCOME FUND - Class I Prospectus - SIMT CORE FIXED INCOME FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>020169 - Disclosure - Risk/Return Detail Data {Elements} - CORE FIXED INCOME FUND - Class I Prospectus - SIMT CORE FIXED INCOME FUND (CLASS I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsCOREFIXEDINCOMEFUNDClassIProspectusSIMTCOREFIXEDINCOMEFUNDCLASSI</Role>
      <ShortName>Risk/Return Detail Data- CORE FIXED INCOME FUND - Class I Prospectus - SIMT CORE FIXED INCOME FUND (CLASS I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>020170 - Document - Risk/Return Summary {Unlabeled} - HIGH YIELD BOND FUND - Class I Prospectus - SIMT HIGH YIELD BOND FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledHIGHYIELDBONDFUNDClassIProspectusSIMTHIGHYIELDBONDFUNDClassI</Role>
      <ShortName>Risk/Return Summary- HIGH YIELD BOND FUND - Class I Prospectus - SIMT HIGH YIELD BOND FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R82.htm</HtmlFileName>
      <LongName>020171 - Disclosure - Risk/Return Detail Data {Elements} - HIGH YIELD BOND FUND - Class I Prospectus - SIMT HIGH YIELD BOND FUND (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsHIGHYIELDBONDFUNDClassIProspectusSIMTHIGHYIELDBONDFUNDClassI</Role>
      <ShortName>Risk/Return Detail Data- HIGH YIELD BOND FUND - Class I Prospectus - SIMT HIGH YIELD BOND FUND (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>82</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R83.htm</HtmlFileName>
      <LongName>020172 - Document - Risk/Return Summary {Unlabeled} - REAL RETURN FUND - Class I Prospectus - SIMT Real Return Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALRETURNFUNDClassIProspectusSIMTRealReturnFundClassI</Role>
      <ShortName>Risk/Return Summary- REAL RETURN FUND - Class I Prospectus - SIMT Real Return Fund (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>83</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R84.htm</HtmlFileName>
      <LongName>020173 - Disclosure - Risk/Return Detail Data {Elements} - REAL RETURN FUND - Class I Prospectus - SIMT Real Return Fund (Class I)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALRETURNFUNDClassIProspectusSIMTRealReturnFundClassI</Role>
      <ShortName>Risk/Return Detail Data- REAL RETURN FUND - Class I Prospectus - SIMT Real Return Fund (Class I)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>84</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R85.htm</HtmlFileName>
      <LongName>020174 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP FUND - Class Y Prospectus - SIMT Large Cap Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPFUNDClassYProspectusSIMTLargeCapFundClassY</Role>
      <ShortName>Risk/Return Summary- LARGE CAP FUND - Class Y Prospectus - SIMT Large Cap Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>85</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R86.htm</HtmlFileName>
      <LongName>020175 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP FUND - Class Y Prospectus - SIMT Large Cap Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPFUNDClassYProspectusSIMTLargeCapFundClassY</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP FUND - Class Y Prospectus - SIMT Large Cap Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>86</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R87.htm</HtmlFileName>
      <LongName>020176 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP VALUE FUND - Class Y Prospectus - SIMT LARGE CAP VALUE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPVALUEFUNDClassYProspectusSIMTLARGECAPVALUEFUNDClassY</Role>
      <ShortName>Risk/Return Summary- LARGE CAP VALUE FUND - Class Y Prospectus - SIMT LARGE CAP VALUE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>87</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R88.htm</HtmlFileName>
      <LongName>020177 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP VALUE FUND - Class Y Prospectus - SIMT LARGE CAP VALUE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPVALUEFUNDClassYProspectusSIMTLARGECAPVALUEFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP VALUE FUND - Class Y Prospectus - SIMT LARGE CAP VALUE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>88</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R89.htm</HtmlFileName>
      <LongName>020178 - Document - Risk/Return Summary {Unlabeled} - LARGE CAP GROWTH FUND - Class Y Prospectus - SIMT LARGE CAP GROWTH FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledLARGECAPGROWTHFUNDClassYProspectusSIMTLARGECAPGROWTHFUNDClassY</Role>
      <ShortName>Risk/Return Summary- LARGE CAP GROWTH FUND - Class Y Prospectus - SIMT LARGE CAP GROWTH FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>89</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R90.htm</HtmlFileName>
      <LongName>020179 - Disclosure - Risk/Return Detail Data {Elements} - LARGE CAP GROWTH FUND - Class Y Prospectus - SIMT LARGE CAP GROWTH FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsLARGECAPGROWTHFUNDClassYProspectusSIMTLARGECAPGROWTHFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- LARGE CAP GROWTH FUND - Class Y Prospectus - SIMT LARGE CAP GROWTH FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>90</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R91.htm</HtmlFileName>
      <LongName>020180 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED LARGE CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDLARGECAPFUNDClassYProspectusSIMTTAXMANAGEDLARGECAPFUNDClassY</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED LARGE CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>91</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R92.htm</HtmlFileName>
      <LongName>020181 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED LARGE CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDLARGECAPFUNDClassYProspectusSIMTTAXMANAGEDLARGECAPFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED LARGE CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED LARGE CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>92</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R93.htm</HtmlFileName>
      <LongName>020182 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP FUND - Class Y Prospectus - SIMT Small Cap Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPFUNDClassYProspectusSIMTSmallCapFundClassY</Role>
      <ShortName>Risk/Return Summary- SMALL CAP FUND - Class Y Prospectus - SIMT Small Cap Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>93</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R94.htm</HtmlFileName>
      <LongName>020183 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP FUND - Class Y Prospectus - SIMT Small Cap Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPFUNDClassYProspectusSIMTSmallCapFundClassY</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP FUND - Class Y Prospectus - SIMT Small Cap Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>94</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R95.htm</HtmlFileName>
      <LongName>020184 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP VALUE FUND - Class Y Prospectus - SIMT SMALL CAP VALUE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPVALUEFUNDClassYProspectusSIMTSMALLCAPVALUEFUNDClassY</Role>
      <ShortName>Risk/Return Summary- SMALL CAP VALUE FUND - Class Y Prospectus - SIMT SMALL CAP VALUE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>95</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R96.htm</HtmlFileName>
      <LongName>020185 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP VALUE FUND - Class Y Prospectus - SIMT SMALL CAP VALUE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPVALUEFUNDClassYProspectusSIMTSMALLCAPVALUEFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP VALUE FUND - Class Y Prospectus - SIMT SMALL CAP VALUE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>96</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R97.htm</HtmlFileName>
      <LongName>020186 - Document - Risk/Return Summary {Unlabeled} - SMALL CAP GROWTH FUND - Class Y Prospectus - SIMT SMALL CAP GROWTH FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledSMALLCAPGROWTHFUNDClassYProspectusSIMTSMALLCAPGROWTHFUNDClassY</Role>
      <ShortName>Risk/Return Summary- SMALL CAP GROWTH FUND - Class Y Prospectus - SIMT SMALL CAP GROWTH FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>97</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R98.htm</HtmlFileName>
      <LongName>020187 - Disclosure - Risk/Return Detail Data {Elements} - SMALL CAP GROWTH FUND - Class Y Prospectus - SIMT SMALL CAP GROWTH FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsSMALLCAPGROWTHFUNDClassYProspectusSIMTSMALLCAPGROWTHFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- SMALL CAP GROWTH FUND - Class Y Prospectus - SIMT SMALL CAP GROWTH FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>98</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R99.htm</HtmlFileName>
      <LongName>020188 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED SMALL/MID CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDSMALLMIDCAPFUNDClassYProspectusSIMTTAXMANAGEDSMALLMIDCAPFUNDClassY</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED SMALL/MID CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>99</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R100.htm</HtmlFileName>
      <LongName>020189 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED SMALL/MID CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDSMALLMIDCAPFUNDClassYProspectusSIMTTAXMANAGEDSMALLMIDCAPFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED SMALL/MID CAP FUND - Class Y Prospectus - SIMT TAX-MANAGED SMALL/MID CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>100</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R101.htm</HtmlFileName>
      <LongName>020190 - Document - Risk/Return Summary {Unlabeled} - MID-CAP FUND - Class Y Prospectus - SIMT MID CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMIDCAPFUNDClassYProspectusSIMTMIDCAPFUNDClassY</Role>
      <ShortName>Risk/Return Summary- MID-CAP FUND - Class Y Prospectus - SIMT MID CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>101</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R102.htm</HtmlFileName>
      <LongName>020191 - Disclosure - Risk/Return Detail Data {Elements} - MID-CAP FUND - Class Y Prospectus - SIMT MID CAP FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMIDCAPFUNDClassYProspectusSIMTMIDCAPFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- MID-CAP FUND - Class Y Prospectus - SIMT MID CAP FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>102</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R103.htm</HtmlFileName>
      <LongName>020192 - Document - Risk/Return Summary {Unlabeled} - U.S. MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT US MANAGED VOLATILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledUSMANAGEDVOLATILITYFUNDClassYProspectusSIMTUSMANAGEDVOLATILITYFUNDClassY</Role>
      <ShortName>Risk/Return Summary- U.S. MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT US MANAGED VOLATILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>103</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R104.htm</HtmlFileName>
      <LongName>020193 - Disclosure - Risk/Return Detail Data {Elements} - U.S. MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT US MANAGED VOLATILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsUSMANAGEDVOLATILITYFUNDClassYProspectusSIMTUSMANAGEDVOLATILITYFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- U.S. MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT US MANAGED VOLATILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>104</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R105.htm</HtmlFileName>
      <LongName>020194 - Document - Risk/Return Summary {Unlabeled} - GLOBAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledGLOBALMANAGEDVOLATILITYFUNDClassYProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDClassY</Role>
      <ShortName>Risk/Return Summary- GLOBAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>105</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R106.htm</HtmlFileName>
      <LongName>020195 - Disclosure - Risk/Return Detail Data {Elements} - GLOBAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsGLOBALMANAGEDVOLATILITYFUNDClassYProspectusSIMTGLOBALMANAGEDVOLATILITYFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- GLOBAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT GLOBAL MANAGED VOLATILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>106</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R107.htm</HtmlFileName>
      <LongName>020196 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDMANAGEDVOLATILITYFUNDClassYProspectusSIMTTaxManagedManagedVolatilityFundClassY</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>107</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R108.htm</HtmlFileName>
      <LongName>020197 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDMANAGEDVOLATILITYFUNDClassYProspectusSIMTTaxManagedManagedVolatilityFundClassY</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed Managed Volatility Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>108</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R109.htm</HtmlFileName>
      <LongName>020198 - Document - Risk/Return Summary {Unlabeled} - TAX-MANAGED INTERNATIONAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXMANAGEDINTERNATIONALMANAGEDVOLATILITYFUNDClassYProspectusSIMTTaxManagedInternationalManagedVolatilityFundClassY</Role>
      <ShortName>Risk/Return Summary- TAX-MANAGED INTERNATIONAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>109</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R110.htm</HtmlFileName>
      <LongName>020199 - Disclosure - Risk/Return Detail Data {Elements} - TAX-MANAGED INTERNATIONAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXMANAGEDINTERNATIONALMANAGEDVOLATILITYFUNDClassYProspectusSIMTTaxManagedInternationalManagedVolatilityFundClassY</Role>
      <ShortName>Risk/Return Detail Data- TAX-MANAGED INTERNATIONAL MANAGED VOLATILITY FUND - Class Y Prospectus - SIMT Tax-Managed International Managed Volatility Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>110</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R111.htm</HtmlFileName>
      <LongName>020200 - Document - Risk/Return Summary {Unlabeled} - REAL ESTATE FUND - Class Y Prospectus - SIMT REAL ESTATE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALESTATEFUNDClassYProspectusSIMTREALESTATEFUNDClassY</Role>
      <ShortName>Risk/Return Summary- REAL ESTATE FUND - Class Y Prospectus - SIMT REAL ESTATE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>111</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R112.htm</HtmlFileName>
      <LongName>020201 - Disclosure - Risk/Return Detail Data {Elements} - REAL ESTATE FUND - Class Y Prospectus - SIMT REAL ESTATE FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALESTATEFUNDClassYProspectusSIMTREALESTATEFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- REAL ESTATE FUND - Class Y Prospectus - SIMT REAL ESTATE FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>112</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R113.htm</HtmlFileName>
      <LongName>020202 - Document - Risk/Return Summary {Unlabeled} - CORE FIXED INCOME FUND - Class Y Prospectus - SIMT CORE FIXED INCOME FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledCOREFIXEDINCOMEFUNDClassYProspectusSIMTCOREFIXEDINCOMEFUNDClassY</Role>
      <ShortName>Risk/Return Summary- CORE FIXED INCOME FUND - Class Y Prospectus - SIMT CORE FIXED INCOME FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>113</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R114.htm</HtmlFileName>
      <LongName>020203 - Disclosure - Risk/Return Detail Data {Elements} - CORE FIXED INCOME FUND - Class Y Prospectus - SIMT CORE FIXED INCOME FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsCOREFIXEDINCOMEFUNDClassYProspectusSIMTCOREFIXEDINCOMEFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- CORE FIXED INCOME FUND - Class Y Prospectus - SIMT CORE FIXED INCOME FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>114</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R115.htm</HtmlFileName>
      <LongName>020204 - Document - Risk/Return Summary {Unlabeled} - HIGH YIELD BOND FUND - Class Y Prospectus - SIMT HIGH YIELD BOND FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledHIGHYIELDBONDFUNDClassYProspectusSIMTHIGHYIELDBONDFUNDClassY</Role>
      <ShortName>Risk/Return Summary- HIGH YIELD BOND FUND - Class Y Prospectus - SIMT HIGH YIELD BOND FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>115</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R116.htm</HtmlFileName>
      <LongName>020205 - Disclosure - Risk/Return Detail Data {Elements} - HIGH YIELD BOND FUND - Class Y Prospectus - SIMT HIGH YIELD BOND FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsHIGHYIELDBONDFUNDClassYProspectusSIMTHIGHYIELDBONDFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- HIGH YIELD BOND FUND - Class Y Prospectus - SIMT HIGH YIELD BOND FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>116</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R117.htm</HtmlFileName>
      <LongName>020206 - Document - Risk/Return Summary {Unlabeled} - CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Conservative Income Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledCONSERVATIVEINCOMEFUNDClassYProspectusSIMTConservativeIncomeFundClassY</Role>
      <ShortName>Risk/Return Summary- CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Conservative Income Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>117</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R118.htm</HtmlFileName>
      <LongName>020207 - Disclosure - Risk/Return Detail Data {Elements} - CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Conservative Income Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsCONSERVATIVEINCOMEFUNDClassYProspectusSIMTConservativeIncomeFundClassY</Role>
      <ShortName>Risk/Return Detail Data- CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Conservative Income Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>118</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R119.htm</HtmlFileName>
      <LongName>020208 - Document - Risk/Return Summary {Unlabeled} - TAX-FREE CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Tax-Free Conservative Income Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledTAXFREECONSERVATIVEINCOMEFUNDClassYProspectusSIMTTaxFreeConservativeIncomeFundClassY</Role>
      <ShortName>Risk/Return Summary- TAX-FREE CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Tax-Free Conservative Income Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>119</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R120.htm</HtmlFileName>
      <LongName>020209 - Disclosure - Risk/Return Detail Data {Elements} - TAX-FREE CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Tax-Free Conservative Income Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsTAXFREECONSERVATIVEINCOMEFUNDClassYProspectusSIMTTaxFreeConservativeIncomeFundClassY</Role>
      <ShortName>Risk/Return Detail Data- TAX-FREE CONSERVATIVE INCOME FUND - Class Y Prospectus - SIMT Tax-Free Conservative Income Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>120</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R121.htm</HtmlFileName>
      <LongName>020210 - Document - Risk/Return Summary {Unlabeled} - REAL RETURN FUND - Class Y Prospectus - SIMT Real Return Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledREALRETURNFUNDClassYProspectusSIMTRealReturnFundClassY</Role>
      <ShortName>Risk/Return Summary- REAL RETURN FUND - Class Y Prospectus - SIMT Real Return Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>121</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R122.htm</HtmlFileName>
      <LongName>020211 - Disclosure - Risk/Return Detail Data {Elements} - REAL RETURN FUND - Class Y Prospectus - SIMT Real Return Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsREALRETURNFUNDClassYProspectusSIMTRealReturnFundClassY</Role>
      <ShortName>Risk/Return Detail Data- REAL RETURN FUND - Class Y Prospectus - SIMT Real Return Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>122</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R123.htm</HtmlFileName>
      <LongName>020212 - Document - Risk/Return Summary {Unlabeled} - DYNAMIC ASSET ALLOCATION FUND - Class Y Prospectus - SIMT Dynamic Asset Allocation Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledDYNAMICASSETALLOCATIONFUNDClassYProspectusSIMTDynamicAssetAllocationFundClassY</Role>
      <ShortName>Risk/Return Summary- DYNAMIC ASSET ALLOCATION FUND - Class Y Prospectus - SIMT Dynamic Asset Allocation Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>123</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R124.htm</HtmlFileName>
      <LongName>020213 - Disclosure - Risk/Return Detail Data {Elements} - DYNAMIC ASSET ALLOCATION FUND - Class Y Prospectus - SIMT Dynamic Asset Allocation Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsDYNAMICASSETALLOCATIONFUNDClassYProspectusSIMTDynamicAssetAllocationFundClassY</Role>
      <ShortName>Risk/Return Detail Data- DYNAMIC ASSET ALLOCATION FUND - Class Y Prospectus - SIMT Dynamic Asset Allocation Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>124</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R125.htm</HtmlFileName>
      <LongName>020214 - Document - Risk/Return Summary {Unlabeled} - MULTI-STRATEGY ALTERNATIVE FUND - Class Y Prospectus - SIMT Multi-Strategy Alternative Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTISTRATEGYALTERNATIVEFUNDClassYProspectusSIMTMultiStrategyAlternativeFundClassY</Role>
      <ShortName>Risk/Return Summary- MULTI-STRATEGY ALTERNATIVE FUND - Class Y Prospectus - SIMT Multi-Strategy Alternative Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>125</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R126.htm</HtmlFileName>
      <LongName>020215 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-STRATEGY ALTERNATIVE FUND - Class Y Prospectus - SIMT Multi-Strategy Alternative Fund (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTISTRATEGYALTERNATIVEFUNDClassYProspectusSIMTMultiStrategyAlternativeFundClassY</Role>
      <ShortName>Risk/Return Detail Data- MULTI-STRATEGY ALTERNATIVE FUND - Class Y Prospectus - SIMT Multi-Strategy Alternative Fund (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>126</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R127.htm</HtmlFileName>
      <LongName>020216 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET ACCUMULATION FUND - Class F Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETACCUMULATIONFUNDClassFProspectusSIMTMULTIASSETACCUMULATIONFUNDClassF</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET ACCUMULATION FUND - Class F Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>127</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R128.htm</HtmlFileName>
      <LongName>020217 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET ACCUMULATION FUND - Class F Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETACCUMULATIONFUNDClassFProspectusSIMTMULTIASSETACCUMULATIONFUNDClassF</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET ACCUMULATION FUND - Class F Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>128</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R129.htm</HtmlFileName>
      <LongName>020218 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET INCOME FUND - Class F Prospectus - SIMT MULTI-ASSET INCOME FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETINCOMEFUNDClassFProspectusSIMTMULTIASSETINCOMEFUNDClassF</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET INCOME FUND - Class F Prospectus - SIMT MULTI-ASSET INCOME FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>129</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R130.htm</HtmlFileName>
      <LongName>020219 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET INCOME FUND - Class F Prospectus - SIMT MULTI-ASSET INCOME FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETINCOMEFUNDClassFProspectusSIMTMULTIASSETINCOMEFUNDClassF</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET INCOME FUND - Class F Prospectus - SIMT MULTI-ASSET INCOME FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>130</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R131.htm</HtmlFileName>
      <LongName>020220 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET INFLATION MANAGED FUND - Class F Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETINFLATIONMANAGEDFUNDClassFProspectusSIMTMULTIASSETINFLATIONMANAGEDFUNDClassF</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET INFLATION MANAGED FUND - Class F Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>131</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R132.htm</HtmlFileName>
      <LongName>020221 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET INFLATION MANAGED FUND - Class F Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETINFLATIONMANAGEDFUNDClassFProspectusSIMTMULTIASSETINFLATIONMANAGEDFUNDClassF</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET INFLATION MANAGED FUND - Class F Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>132</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R133.htm</HtmlFileName>
      <LongName>020222 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET CAPITAL STABILITY FUND - Class F Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETCAPITALSTABILITYFUNDClassFProspectusSIMTMULTIASSETCAPITALSTABILITYFUNDClassF</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET CAPITAL STABILITY FUND - Class F Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>133</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R134.htm</HtmlFileName>
      <LongName>020223 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET CAPITAL STABILITY FUND - Class F Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class F)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETCAPITALSTABILITYFUNDClassFProspectusSIMTMULTIASSETCAPITALSTABILITYFUNDClassF</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET CAPITAL STABILITY FUND - Class F Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class F)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>134</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R135.htm</HtmlFileName>
      <LongName>020224 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET ACCUMULATION FUND - Class Y Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETACCUMULATIONFUNDClassYProspectusSIMTMULTIASSETACCUMULATIONFUNDClassY</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET ACCUMULATION FUND - Class Y Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>135</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R136.htm</HtmlFileName>
      <LongName>020225 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET ACCUMULATION FUND - Class Y Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETACCUMULATIONFUNDClassYProspectusSIMTMULTIASSETACCUMULATIONFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET ACCUMULATION FUND - Class Y Prospectus - SIMT MULTI-ASSET ACCUMULATION FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>136</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R137.htm</HtmlFileName>
      <LongName>020226 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET INCOME FUND - Class Y Prospectus - SIMT MULTI-ASSET INCOME FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETINCOMEFUNDClassYProspectusSIMTMULTIASSETINCOMEFUNDClassY</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET INCOME FUND - Class Y Prospectus - SIMT MULTI-ASSET INCOME FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>137</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R138.htm</HtmlFileName>
      <LongName>020227 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET INCOME FUND - Class Y Prospectus - SIMT MULTI-ASSET INCOME FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETINCOMEFUNDClassYProspectusSIMTMULTIASSETINCOMEFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET INCOME FUND - Class Y Prospectus - SIMT MULTI-ASSET INCOME FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>138</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R139.htm</HtmlFileName>
      <LongName>020228 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET INFLATION MANAGED FUND - Class Y Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETINFLATIONMANAGEDFUNDClassYProspectusSIMTMULTIASSETINFLATIONMANAGEDFUNDClassY</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET INFLATION MANAGED FUND - Class Y Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>139</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R140.htm</HtmlFileName>
      <LongName>020229 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET INFLATION MANAGED FUND - Class Y Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETINFLATIONMANAGEDFUNDClassYProspectusSIMTMULTIASSETINFLATIONMANAGEDFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET INFLATION MANAGED FUND - Class Y Prospectus - SIMT MULTI-ASSET INFLATION MANAGED FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>140</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R141.htm</HtmlFileName>
      <LongName>020230 - Document - Risk/Return Summary {Unlabeled} - MULTI-ASSET CAPITAL STABILITY FUND - Class Y Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DocumentRiskReturnSummaryUnlabeledMULTIASSETCAPITALSTABILITYFUNDClassYProspectusSIMTMULTIASSETCAPITALSTABILITYFUNDClassY</Role>
      <ShortName>Risk/Return Summary- MULTI-ASSET CAPITAL STABILITY FUND - Class Y Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>141</Position>
    </Report>
    <Report instance="tm262170d1_485bpos.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R142.htm</HtmlFileName>
      <LongName>020231 - Disclosure - Risk/Return Detail Data {Elements} - MULTI-ASSET CAPITAL STABILITY FUND - Class Y Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class Y)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.seic.com/20260128/role/DisclosureRiskReturnDetailDataElementsMULTIASSETCAPITALSTABILITYFUNDClassYProspectusSIMTMULTIASSETCAPITALSTABILITYFUNDClassY</Role>
      <ShortName>Risk/Return Detail Data- MULTI-ASSET CAPITAL STABILITY FUND - Class Y Prospectus - SIMT MULTI-ASSET CAPITAL STABILITY FUND (Class Y)</ShortName>
      <MenuCategory>Risk/Return</MenuCategory>
      <Position>142</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ck0000804239-20260128.xsd</File>
    <File>ck0000804239-20260128_def.xml</File>
    <File>ck0000804239-20260128_lab.xml</File>
    <File>ck0000804239-20260128_pre.xml</File>
    <File doctype="485BPOS" isN1a="true" isOEF="true" isRRorOEF="true" isUsgaap="true" original="tm262170d1_485bpos.htm">tm262170d1_485bpos.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>j2621702_ac001.jpg</File>
    <File>j2621702_ba002.jpg</File>
    <File>j2621702_ba003.jpg</File>
    <File>j2621702_ba004.jpg</File>
    <File>j2621702_ba005.jpg</File>
    <File>j2621702_bc006.jpg</File>
    <File>j2621702_bc007.jpg</File>
    <File>j2621702_bc008.jpg</File>
    <File>j2621702_bc009.jpg</File>
    <File>j2621702_be010.jpg</File>
    <File>j2621702_be011.jpg</File>
    <File>j2621702_be012.jpg</File>
    <File>j2621702_be013.jpg</File>
    <File>j2621702_bg014.jpg</File>
    <File>j2621702_bg015.jpg</File>
    <File>j2621702_bg016.jpg</File>
    <File>j2621702_bg017.jpg</File>
    <File>j2621702_bi001.jpg</File>
    <File>j2621702_bi002.jpg</File>
    <File>j2621702_bi003.jpg</File>
    <File>j2621702_bi004.jpg</File>
    <File>j2621702_bk022.jpg</File>
    <File>j2621702_bk023.jpg</File>
    <File>j2621702_bk024.jpg</File>
    <File>j2621702_za025.jpg</File>
    <File>j2621703_ac001.jpg</File>
    <File>j2621703_ba002.jpg</File>
    <File>j2621703_ba003.jpg</File>
    <File>j2621703_ba004.jpg</File>
    <File>j2621703_ba005.jpg</File>
    <File>j2621703_bc006.jpg</File>
    <File>j2621703_bc007.jpg</File>
    <File>j2621703_bc008.jpg</File>
    <File>j2621703_bc009.jpg</File>
    <File>j2621703_be001.jpg</File>
    <File>j2621703_be002.jpg</File>
    <File>j2621703_be003.jpg</File>
    <File>j2621703_be004.jpg</File>
    <File>j2621703_bg014.jpg</File>
    <File>j2621703_bg015.jpg</File>
    <File>j2621703_za016.jpg</File>
    <File>j2621704_ac001.jpg</File>
    <File>j2621704_ba002.jpg</File>
    <File>j2621704_ba003.jpg</File>
    <File>j2621704_ba004.jpg</File>
    <File>j2621704_ba005.jpg</File>
    <File>j2621704_bc006.jpg</File>
    <File>j2621704_bc007.jpg</File>
    <File>j2621704_bc008.jpg</File>
    <File>j2621704_bc009.jpg</File>
    <File>j2621704_bc010.jpg</File>
    <File>j2621704_be011.jpg</File>
    <File>j2621704_be012.jpg</File>
    <File>j2621704_be013.jpg</File>
    <File>j2621704_be014.jpg</File>
    <File>j2621704_bg001.jpg</File>
    <File>j2621704_bg002.jpg</File>
    <File>j2621704_bg003.jpg</File>
    <File>j2621704_bg004.jpg</File>
    <File>j2621704_bi019.jpg</File>
    <File>j2621704_bi020.jpg</File>
    <File>j2621704_bi021.jpg</File>
    <File>j2621704_bi022.jpg</File>
    <File>j2621704_za023.jpg</File>
    <File>j2621705_ac001.jpg</File>
    <File>j2621705_ba002.jpg</File>
    <File>j2621705_ba003.jpg</File>
    <File>j2621705_bc004.jpg</File>
    <File>j2621705_bc005.jpg</File>
    <File>j2621705_za006.jpg</File>
    <File>j2621706_ac001.jpg</File>
    <File>j2621706_ba002.jpg</File>
    <File>j2621706_ba003.jpg</File>
    <File>j2621706_bc004.jpg</File>
    <File>j2621706_bc005.jpg</File>
    <File>j2621706_za006.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="6">http://xbrl.sec.gov/dei/2025</BaseTaxonomy>
    <BaseTaxonomy items="6536">http://xbrl.sec.gov/oef/2025</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>false</HasCalculationLinkbase>
</FilingSummary>
