Label	Element	Value
SIMT MULTI-ASSET INFLATION MANAGED FUND
Risk/Return:	rr_RiskReturnAbstract
Supplement to Prospectus [Text Block]	rr_SupplementToProspectusTextBlock	SEI INSTITUTIONAL MANAGED TRUST Multi-Asset Inflation Managed Fund (the "Fund") Supplement Dated May 19, 2022 to the Class F Shares Prospectus (the "Prospectus") dated January 31, 2022 This Supplement provides new and additional information beyond that contained in the Prospectus and should be read in conjunction with such Prospectus.
Risk/Return [Heading]	rr_RiskReturnHeading	Multi-Asset Inflation Managed Fund
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The Prospectus is hereby amended and supplemented to revise the Performance Information for the Fund. In the Fund Summary for the Fund, under the heading titled "Performance Information," the bar chart thereunder is hereby deleted and replaced with the following:
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter: 4.42% (06/30/2021) Worst Quarter: -10.32% (03/31/2020)
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2021
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	4.42%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2020
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(10.32%)
Performance Table Closing [Text Block]	rr_PerformanceTableClosingTextBlock	There are no other changes to the Prospectus. PLEASE RETAIN THIS SUPPLEMENT FOR FUTURE REFERENCE
SIMT MULTI-ASSET INFLATION MANAGED FUND \| Class F
Risk/Return:	rr_RiskReturnAbstract
Annual Return 2013	rr_AnnualReturn2013	(6.00%)
Annual Return 2014	rr_AnnualReturn2014	(4.68%)
Annual Return 2015	rr_AnnualReturn2015	(4.12%)
Annual Return 2016	rr_AnnualReturn2016	3.52%
Annual Return 2017	rr_AnnualReturn2017	(1.96%)
Annual Return 2018	rr_AnnualReturn2018	(3.64%)
Annual Return 2019	rr_AnnualReturn2019	5.68%
Annual Return 2020	rr_AnnualReturn2020	(1.59%)
Annual Return 2021	rr_AnnualReturn2021	10.82%

If the Fund has annual returns for at least one calendar year, provide a bar chart showing the Fund's annual total returns for each of the last 10 calendar years (or for the life of the Fund if less than 10 years), but only for periods subsequent to the effective date of the Fund's registration statement. Present the corresponding numerical return adjacent to each bar. If the Fund's fiscal year is other than a calendar year, include the year-to-date return information as of the end of the most recent quarter in a footnote to the bar chart. Following the bar chart, disclose the Fund's highest and lowest return for a quarter during the 10 years or other period of the bar chart. When a Multiple Class Fund offers more than one Class in the prospectus, provide annual total returns in the bar chart for only one of those Classes. The Fund can select which Class to include (e.g., the oldest Class, the Class with the greatest net assets).

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 4
-Subsection b
-Paragraph 2
-Subparagraph ii