Label	Element	Value
Risk Return [Abstract]	rr_RiskReturnAbstract
ProspectusDate	rr_ProspectusDate	Jan. 31, 2012
SIMT HIGH YIELD BOND FUND (Second Prospectus Summary) | SIMT HIGH YIELD BOND FUND
Risk Return [Abstract]	rr_RiskReturnAbstract
Risk/Return, Heading	rr_RiskReturnHeading	HIGH YIELD BOND FUND
Investment Objective, Heading	rr_ObjectiveHeading	Investment Goal
investment Objective, Primary	rr_ObjectivePrimaryTextBlock	Total return.
Expense, Heading	rr_ExpenseHeading	Fees and Expenses
Expense, Narrative	rr_ExpenseNarrativeTextBlock	This table describes the fees and expenses that you may pay if you buy and hold Fund shares.
Shareholder Fees, Caption	rr_ShareholderFeesCaption	SHAREHOLDER FEES (fees paid directly from your investment)
Operating Expenses, Caption	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
Portfolio Turnover	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the Example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 82% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	82.00%
Expenses, Not Correlated to Ratio Due to Acquired Fund Fees	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	Because the Fund incurred AFFE during the most recent fiscal year, the operating expenses in this fee table will not correlate to the expense ratio in the Fund's financial statements (or the "Financial Highlights" section in the prospectus) because the financial statements include only the direct operating expenses incurred by the Fund, not the indirect costs of investing in other investment companies.
Expense Example, Heading	rr_ExpenseExampleHeading	EXAMPLE
Expense Example, Narrative	rr_ExpenseExampleNarrativeTextBlock	This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same.
Expense Example, By Year, Caption	rr_ExpenseExampleByYearCaption	Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Investment Strategy, Heading	rr_StrategyHeading	Principal Investment Strategies
Investment Strategy, Narrative	rr_StrategyNarrativeTextBlock	Under normal circumstances, the High Yield Bond Fund will invest at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in high yield fixed income securities. The Fund will invest primarily in fixed income securities rated below investment grade (junk bonds), including corporate bonds and debentures, convertible and preferred securities, zero coupon obligations and collateralized debt obligations (CDOs) and collateralized loan obligations (CLOs). The Fund uses a multi-manager approach, relying on a number of Sub-Advisers with differing investment philosophies to manage portions of the Fund's portfolio under the general supervision of SIMC. To a limited extent, SIMC may also directly manage a portion of the Fund's portfolio. In managing the Fund's assets, the Sub-Advisers and, to the extent applicable, SIMC, seek to select securities that offer a high current yield as well as total return potential. The Fund's securities seek to be diversified as to issuers and industries. The Fund's average weighted maturity may vary and will generally not exceed ten years. There is no limit on the maturity or credit quality of any security. The Fund will invest primarily in securities rated BB, B, CCC, CC, C and D. However, it may also invest in non-rated securities or securities rated investment grade (AAA, AA, A and BBB). The Fund may also invest in ETFs to gain exposure to a particular portion of the market while awaiting an opportunity to purchase securities directly. The Fund may also invest a portion of its assets in bank loans, which are, generally, non-investment grade (junk) floating rate instruments. The Fund may invest in bank loans in the form of participations in the loans (participations) and assignments of all or a portion of the loans from third parties (assignments).
Risk, Heading	rr_RiskHeading	Principal Risks
Risk, Narrative	rr_RiskNarrativeTextBlock	Bank Loans Risk - With respect to bank loans, the Fund will assume the credit risk of both the borrower of the loan and the lender that is selling the participation in the loan. The Fund may also have difficulty disposing of bank loans because, in certain cases, the market for such instruments is not highly liquid. Below Investment Grade Securities Risk - Fixed income securities rated below investment grade (junk bonds) involve greater risks of default or downgrade and are more volatile than investment grade securities because the prospect for repayment of principal and interest of many of these securities is speculative. CDOs and CLOs Risk - CDOs and CLOs are securities backed by an underlying portfolio of debt and loan obligations, respectively. CDOs and CLOs issue classes or "tranches" that vary in risk and yield and may experience substantial losses due to actual defaults, decrease of market value due to collateral defaults and removal of subordinate tranches, market anticipation of defaults and investor aversion to CDO and CLO securities as a class. The risks of investing in CDOs and CLOs depend largely on the tranche invested in and the type of the underlying debts and loans in the tranche of the CDO or CLO, respectively, in which the Fund invests. CDOs and CLOs also carry risks including, but not limited to, interest rate risk and credit risk, which are described below. Convertible and Preferred Securities Risk - Convertible and preferred securities have many of the same characteristics as stocks, including many of the same risks. In addition, convertible securities may be more sensitive to changes in interest rates than stocks. Convertible securities may also have credit ratings below investment grade, meaning that they carry a higher risk of failure by the issuer to pay principal and/or interest when due. Corporate Fixed Income Securities Risk - Corporate fixed income securities respond to economic developments, especially changes in interest rates, as well as perceptions of the creditworthiness and business prospects of individual issuers. Credit Risk - The risk that the issuer of a security or the counterparty to a contract will default or otherwise become unable to honor a financial obligation. Exchange-Traded Funds (ETFs) Risk - The risks of owning shares of an ETF generally reflect the risks of owning the underlying securities the ETF is designed to track, although lack of liquidity in an ETF could result in its value being more volatile than the underlying portfolio securities. Extension Risk - The risk that rising interest rates may extend the duration of a fixed income security, typically reducing the security's value. Fixed Income Market Risk - The prices of the Fund's fixed income securities respond to economic developments, particularly interest rate changes, as well as to perceptions about the creditworthiness of individual issuers, including governments and their agencies. In the case of foreign securities, price fluctuations will reflect international economic and political events, as well as changes in currency valuations relative to the U.S. dollar. Interest Rate Risk - The risk that the value of fixed income securities, including U.S. Government securities, will fall due to rising interest rates. Investment Style Risk - The risk that high yield securities may underperform other segments of the fixed income markets or the fixed income markets as a whole. Liquidity Risk - The risk that certain securities may be difficult or impossible to sell at the time and the price that the Fund would like. The Fund may have to lower the price, sell other securities instead or forego an investment opportunity, any of which could have a negative effect on Fund management or performance. Prepayment Risk - The risk that, with declining interest rates, fixed income securities with stated interest rates may have the principal paid earlier than expected, requiring the Fund to invest the proceeds at generally lower interest rates. Loss of money is a risk of investing in the Fund.
Risk, Lose Money	rr_RiskLoseMoney	Loss of money is a risk of investing in the Fund.
Bar Chart and Performance Table, Heading	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance, Narrative	rr_PerformanceNarrativeTextBlock	The bar chart and the performance table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year for the past ten calendar years and by showing how the Fund's average annual returns for 1, 5 and 10 years, and since the Fund's inception, compared with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. For current performance information, please call 1-800-DIAL-SEI. The Fund's Class I Shares commenced operations on October 1, 2007. Therefore, performance and average annual total returns for the periods prior to October 1, 2007 are calculated using the performance and average annual total returns of the Fund's Class A Shares, adjusted for the higher expenses of the Class I Shares. The Fund's Class A Shares commenced operations on January 11, 1995.
Performance, Information Illustrates Variability of Returns	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and the performance table below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year for the past ten calendar years and by showing how the Fund's average annual returns for 1, 5 and 10 years, and since the Fund's inception, compared with those of a broad measure of market performance.
Performance, Availability Phone Number	rr_PerformanceAvailabilityPhone	1-800-DIAL-SEI
Performance, Past Does Not Indicate Future	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart, Closing	rr_BarChartClosingTextBlock	Best Quarter: 22.00% (06/30/09) Worst Quarter: -21.93% (12/31/08)
Performance Table, Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2011)
Index No Deduction for Fees, Expenses, Taxes	rr_IndexNoDeductionForFeesExpensesTaxes	reflects no deduction for fees, expenses or taxes
Performance Table, Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table, Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Your actual after-tax returns will depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
Performance Table, Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Your actual after-tax returns will depend on your tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans or individual retirement accounts.
SIMT HIGH YIELD BOND FUND (Second Prospectus Summary) | SIMT HIGH YIELD BOND FUND | BofA Merrill Lynch U.S. High Yield Constrained Index Return
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	BofA Merrill Lynch U.S. High Yield Constrained Index Return (reflects no deduction for fees, expenses or taxes)
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	4.37%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	7.54%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	8.74%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception		[1]
SIMT HIGH YIELD BOND FUND (Second Prospectus Summary) | SIMT HIGH YIELD BOND FUND | Class I
Risk Return [Abstract]	rr_RiskReturnAbstract
Redemption Fee (applies to a redemption, or series of redemptions, from a single identifiable source that, in the aggregate, exceeds $25 million within any thirty (30) day period)	rr_RedemptionFeeOverRedemption	(1.00%)
Management Fees	rr_ManagementFeesOverAssets	0.49%
Distribution (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.90%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.39%	[2]
Expense Example, With Redemption, 1 Year	rr_ExpenseExampleYear01	142
Expense Example, With Redemption, 3 Years	rr_ExpenseExampleYear03	440
Expense Example, With Redemption, 5 Years	rr_ExpenseExampleYear05	761
Expense Example, With Redemption, 10 Years	rr_ExpenseExampleYear10	1,669
Annual Return 2002	rr_AnnualReturn2002	3.82%
Annual Return 2003	rr_AnnualReturn2003	21.16%
Annual Return 2004	rr_AnnualReturn2004	10.12%
Annual Return 2005	rr_AnnualReturn2005	1.97%
Annual Return 2006	rr_AnnualReturn2006	9.88%
Annual Return 2007	rr_AnnualReturn2007	1.39%
Annual Return 2008	rr_AnnualReturn2008	(30.56%)
Annual Return 2009	rr_AnnualReturn2009	54.44%
Annual Return 2010	rr_AnnualReturn2010	17.17%
Annual Return 2011	rr_AnnualReturn2011	1.91%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	22.00%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(21.93%)
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class I Return Before Taxes
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.91%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	5.36%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	7.26%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	7.09%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 11, 1995
SIMT HIGH YIELD BOND FUND (Second Prospectus Summary) | SIMT HIGH YIELD BOND FUND | Class I | After Taxes on Distributions
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class I Return After Taxes on Distributions
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	(0.71%)
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	2.02%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	4.04%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	3.55%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 11, 1995
SIMT HIGH YIELD BOND FUND (Second Prospectus Summary) | SIMT HIGH YIELD BOND FUND | Class I | After Taxes on Distributions and Sales
Risk Return [Abstract]	rr_RiskReturnAbstract
Average Annual Returns, Label	rr_AverageAnnualReturnLabel	Class I Return After Taxes on Distributions and Sale of Fund Shares
Average Annual Returns, 1 Year	rr_AverageAnnualReturnYear01	1.26%
Average Annual Returns, 5 Years	rr_AverageAnnualReturnYear05	2.52%
Average Annual Returns, 10 Years	rr_AverageAnnualReturnYear10	4.25%
Average Annual Returns, Since Inception	rr_AverageAnnualReturnSinceInception	3.82%
Average Annual Returns, Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 11, 1995

[1] The BofA Merrill Lynch U.S. High Yield Constrained Index Return for the "Since Inception" period is not provided since returns for the index are not available prior to 1996.

[2] Because the Fund incurred AFFE during the most recent fiscal year, the operating expenses in this fee table will not correlate to the expense ratio in the Fund's financial statements (or the "Financial Highlights" section in the prospectus) because the financial statements include only the direct operating expenses incurred by the Fund, not the indirect costs of investing in other investment companies.