3.20.2 html 21 165 1 false 14 0 false 2 false false R1.htm 000001 - Document - Document and Entity Information Sheet http://www.sei.com/20201005/role/DocumentAndEntityInformation Document and Entity Information 1 false true R2.htm 020000 - Document - Risk/Return Summary {Unlabeled} - SIIT LARGE CAP FUND Sheet http://www.sei.com/20201005/role/DocumentRiskReturnSummaryUnlabeledSIITLARGECAPFUND Risk/Return Summary- SIIT LARGE CAP FUND 2 false false R7.htm 020005 - Disclosure - Risk/Return Detail Data {Elements} - SIIT LARGE CAP FUND Sheet http://www.sei.com/20201005/role/DisclosureRiskReturnDetailDataElementsSIITLARGECAPFUND Risk/Return Detail Data- SIIT LARGE CAP FUND 3 false true R8.htm 020006 - Document - Risk/Return Summary {Unlabeled} - SIIT LARGE CAP DISCIPLINED EQUITY FUND Sheet http://www.sei.com/20201005/role/DocumentRiskReturnSummaryUnlabeledSIITLARGECAPDISCIPLINEDEQUITYFUND Risk/Return Summary- SIIT LARGE CAP DISCIPLINED EQUITY FUND 4 false false R13.htm 020011 - Disclosure - Risk/Return Detail Data {Elements} - SIIT LARGE CAP DISCIPLINED EQUITY FUND Sheet http://www.sei.com/20201005/role/DisclosureRiskReturnDetailDataElementsSIITLARGECAPDISCIPLINEDEQUITYFUND Risk/Return Detail Data- SIIT LARGE CAP DISCIPLINED EQUITY FUND 5 false true R14.htm 020012 - Document - Risk/Return Summary {Unlabeled} - SIIT Global Managed Volatility Fund Sheet http://www.sei.com/20201005/role/DocumentRiskReturnSummaryUnlabeledSIITGlobalManagedVolatilityFund Risk/Return Summary- SIIT Global Managed Volatility Fund 6 false false R19.htm 020017 - Disclosure - Risk/Return Detail Data {Elements} - SIIT Global Managed Volatility Fund Sheet http://www.sei.com/20201005/role/DisclosureRiskReturnDetailDataElementsSIITGlobalManagedVolatilityFund Risk/Return Detail Data- SIIT Global Managed Volatility Fund 7 false true R20.htm 020018 - Document - Risk/Return Summary {Unlabeled} - SIIT World Select Equity Fund Sheet http://www.sei.com/20201005/role/DocumentRiskReturnSummaryUnlabeledSIITWorldSelectEquityFund Risk/Return Summary- SIIT World Select Equity Fund 8 false false R25.htm 020023 - Disclosure - Risk/Return Detail Data {Elements} - SIIT World Select Equity Fund Sheet http://www.sei.com/20201005/role/DisclosureRiskReturnDetailDataElementsSIITWorldSelectEquityFund Risk/Return Detail Data- SIIT World Select Equity Fund 9 false false R26.htm 040000 - Disclosure - Risk/Return Detail Data {Elements} Sheet http://xbrl.sec.gov/rr/role/RiskReturnDetailData Risk/Return Detail Data 10 false false All Reports Book All Reports tm2029219-33_497.htm ck0000939934-20201005.xsd ck0000939934-20201005_cal.xml ck0000939934-20201005_def.xml ck0000939934-20201005_lab.xml ck0000939934-20201005_pre.xml j20292193_aa001.jpg j20292193_ba002.jpg j20292193_ba003.jpg j20292193_ba004.jpg j20292193_bc005.jpg j20292193_bc006.jpg j20292193_bc007.jpg j20292193_bc008.jpg j20292193_be009.jpg j20292193_be010.jpg j20292193_be011.jpg j20292193_be012.jpg j20292193_bg013.jpg j20292193_bg014.jpg j20292193_bg015.jpg j20292193_bi016.jpg j20292193_bi017.jpg j20292193_bi018.jpg j20292193_bk019.jpg j20292193_bk020.jpg j20292193_bk021.jpg j20292193_bm022.jpg j20292193_bm023.jpg j20292193_bm024.jpg j20292193_bo025.jpg j20292193_bo026.jpg j20292193_bq027.jpg j20292193_bq028.jpg j20292193_ca029.jpg j20292193_za030.jpg BarChart1.png BarChart2.png BarChart3.png BarChart4.png http://xbrl.sec.gov/dei/2019-01-31 http://xbrl.sec.gov/rr/2018-01-31 true true