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Risk/Return:

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Risk/Return [Heading]

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SDIT SHORT DURATION GOVERNMENT FUND

Objective [Heading]

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Investment Goal

Objective, Primary [Text Block]

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Preserve principal value and maintain a high degree of liquidity while providing current income.

Expense [Heading]

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Fees and Expenses

Shareholder Fees Caption [Text]

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SHAREHOLDER FEES (fees paid directly from your investment)

Operating Expenses Caption [Text]

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ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

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PORTFOLIO TURNOVER

Portfolio Turnover [Text Block]

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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 151% of the average value of its portfolio.

Portfolio Turnover, Rate

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Expense Example [Heading]

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EXAMPLE

Expense Example Narrative [Text Block]

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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 [Text]

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Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Strategy [Heading]

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Principal Investment Strategies

Strategy Narrative [Text Block]

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Under normal circumstances, the Short-Duration Government Fund invests substantially all of its net assets in U.S. Treasury obligations and obligations issued or guaranteed as to principal and interest by agencies or instrumentalities of the U.S. Government, including mortgage-backed securities, and repurchase agreements collateralized by such obligations. The Fund may invest in securities issued by various entities sponsored by the U.S. Government, such as the Federal National Mortgage Association (FNMA or Fannie Mae) and the Federal Home Loan Mortgage Corporation (FHLMC or Freddie Mac). These issuers are chartered or sponsored by acts of Congress; however, their securities are neither issued nor guaranteed by the U.S. Treasury and are not backed by the full faith and credit of the U.S. Government. In addition, the Fund may enter into dollar roll transactions with selected banks and broker-dealers and invest in to-be-announced mortgage-backed securities, futures contracts and forward contracts. The Fund will primarily use futures contracts for hedging purposes to manage the Fund's exposure to interest rate risk. There may also be times when the Fund utilizes futures contracts to take an active position on interest rates to either increase or reduce the interest rate sensitivity of the Fund.

Using a top-down strategy and bottom-up security selection, the sub-adviser (the Sub-Adviser) seeks attractively-valued securities that offer competitive yields. The Sub-Adviser also considers factors such as the anticipated level of interest rates, relative valuations and yield spreads, and the duration of the Fund's entire portfolio. Duration measures the price sensitivity of a fixed income security to changes in interest rates. For example, a five year duration means that the fixed income security will decrease in value by 5% if interest rates rise 1% and increase in value by 5% if interest rates fall 1%. While the Fund may invest in securities with any maturity or duration, the Sub-Adviser will strive to maintain a portfolio duration of up to three years under normal market conditions.

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Principal Risks

Risk Narrative [Text Block]

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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.

Derivatives Risk — The Fund's use of futures contracts and forward contracts is subject to market risk, leverage risk, correlation risk and liquidity risk. Leverage risk and liquidity risk are described below. Market risk is the risk that the market value of an investment may move up and down, sometimes rapidly and unpredictably. Correlation risk is the risk that changes in the value of the derivative may not correlate perfectly with the underlying asset, rate or index. The Fund's use of forward contracts is also subject to credit risk and valuation risk. Valuation risk is the risk that the derivative may be difficult to value and/or valued incorrectly. Credit risk is described above. Each of these risks could cause the Fund to lose more than the principal amount invested in a derivative instrument.

Dollar Rolls Risk — The Fund's investments in dollar rolls may subject the Fund to leverage risk and liquidity risk, both of which are described below.

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. Generally, the Fund's fixed income securities will decrease in value if interest rates rise and vice versa. Declines in dealer market-making capacity as a result of structural or regulatory changes could decrease liquidity and/or increase volatility in the fixed income markets. 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. In response to these events, the Fund's value may fluctuate and/or the Fund may experience increased redemptions from shareholders, which may impact the Fund's liquidity or force the Fund to sell securities into a declining or illiquid market.

Interest Rate Risk — The risk that a rise in interest rates will cause a fall in the value of fixed income securities, including U.S. Government securities, in which the Fund invests. Although U.S. Government securities are considered to be among the safest investments, they are not guaranteed against price movements due to changing interest rates. A low interest rate environment may present greater interest rate risk, because there may be a greater likelihood of rates increasing and rates may increase more rapidly.

Investment Style Risk — The risk that short-duration U.S. Government fixed income securities may underperform other segments of the fixed income markets or the fixed income markets as a whole.

Leverage Risk — The Fund's use of derivatives or investments in repurchase agreements may result in the Fund's total investment exposure substantially exceeding the value of its portfolio securities and the Fund's investment returns depending substantially on the performance of securities that the Fund may not directly own. The use of leverage can amplify the effects of market volatility on the Fund's share price and may also cause the Fund to liquidate portfolio positions when it would not be advantageous to do so in order to satisfy its obligations. The Fund's use of leverage may result in a heightened risk of investment loss.

Liquidity Risk — The risk that certain securities may be difficult or impossible to sell at the time and the price that the seller would like. The seller 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.

Market Risk — The risk that the market value of a security may move up and down, sometimes rapidly and unpredictably. Market risk may affect a single issuer, an industry, a sector or the bond market as a whole.

Mortgage-Backed Securities Risk — Mortgage-backed securities are affected by, among other things, interest rate changes and the possibility of prepayment of the underlying mortgage loans. Mortgage-backed securities are also subject to the risk that underlying borrowers will be unable to meet their obligations.

Opportunity Risk — The risk of missing out on an investment opportunity because the assets necessary to take advantage of it are tied up in other investments.

Portfolio Turnover Risk — Due to its investment strategy, the Fund may buy and sell securities frequently. This may result in higher transaction costs and additional capital gains tax liabilities.

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.

Repurchase Agreement Risk — Although repurchase agreement transactions must be fully collateralized at all times, they generally create leverage and involve some counterparty risk to the Fund whereby a defaulting counterparty could delay or prevent the Fund's recovery of collateral.

U.S. Government Securities Risk — Although U.S. Government securities are considered to be among the safest investments, they are not guaranteed against price movements due to changing interest rates. Obligations issued by some U.S. Government agencies are backed by the U.S. Treasury, while others are backed solely by the ability of the agency to borrow from the U.S. Treasury or by the agency's own resources.

Investing in the Fund involves risk, and there is no guarantee that the Fund will achieve its investment goal. You could lose money on your investment in the Fund, just as you could with other investments.

Risk Lose Money [Text]

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You could lose money on your investment in the Fund, just as you could with other investments.

Bar Chart and Performance Table [Heading]

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Performance Information

Performance Narrative [Text Block]

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The bar chart and the performance table below provide some indication of the risks of investing in the Class Y Shares of the Fund by showing changes in the Fund's Class A Shares' performance from year to year for the past ten calendar years and by showing how the Fund's Class A Shares' average annual returns for 1, 5 and 10 years, and since the Fund's inception, compare with those of a broad measure of market performance. The Fund's Class A Shares are offered in a separate prospectus. Because Class Y Shares are invested in the same portfolio of securities, returns for Class Y Shares would have been substantially similar to those of Class A Shares, shown here, and would have differed only to the extent that Class Y Shares have lower total annual fund operating expenses than Class A Shares. 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.

Performance Information Illustrates Variability of Returns [Text]

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The bar chart and the performance table below provide some indication of the risks of investing in the Class Y Shares of the Fund by showing changes in the Fund's Class A Shares' performance from year to year for the past ten calendar years and by showing how the Fund's Class A Shares' average annual returns for 1, 5 and 10 years, and since the Fund's inception, compare with those of a broad measure of market performance.

Performance One Year or Less [Text]

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The Fund's Class Y Shares commenced operations on December 31, 2014, and therefore do not have performance history for a full calendar year.

Performance Availability Phone [Text]

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1-800-DIAL-SEI

Performance Past Does Not Indicate Future [Text]

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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 [Text Block]

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Best Quarter: 2.42% (03/31/08)

Worst Quarter: -1.00% (06/30/13)

Bar Chart, Returns for Class Not Offered in Prospectus [Text]

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The Fund's Class A Shares are offered in a separate prospectus.

Highest Quarterly Return, Label

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Best Quarter:

Highest Quarterly Return, Date

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Mar. 31, 2008

Highest Quarterly Return

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Lowest Quarterly Return, Label

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Worst Quarter:

Lowest Quarterly Return, Date

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Jun. 30, 2013

Lowest Quarterly Return

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Performance Table Heading

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Average Annual Total Returns (for the periods ended December 31, 2014)

Index No Deduction for Fees, Expenses, Taxes [Text]

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(reflects no deduction for fees, expenses or taxes)

Performance Table Uses Highest Federal Rate

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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

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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 Explanation after Tax Higher

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In the event of negative performance, the Fund's returns after taxes on distributions and sale of Fund Shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sale of Fund Shares. As a result, the Fund's returns after taxes on distributions and sale of Fund Shares may exceed the Fund's returns before taxes and/or returns after taxes on distributions.

Performance Table Narrative

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The Fund's Class Y Shares commenced operations on December 31, 2014, and therefore do not have performance history for a full calendar year. This table compares the Fund's Class A Shares' average annual total returns for the period ended December 31, 2014 to those of an appropriate broad based index.

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. In the event of negative performance, the Fund's returns after taxes on distributions and sale of Fund Shares are calculated assuming that an investor has sufficient capital gains of the same character from other investments to offset any capital losses from the sale of Fund Shares. As a result, the Fund's returns after taxes on distributions and sale of Fund Shares may exceed the Fund's returns before taxes and/or returns after taxes on distributions.

BofA Merrill Lynch 1-3 Year U.S. Treasury Bond Index Return (reflects no deduction for fees, expenses or taxes)

Risk/Return:

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BofA Merrill Lynch 1-3 Year U.S. Treasury Bond Index Return (reflects no deduction for fees, expenses or taxes)

Average Annual Returns, 1 Year

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Average Annual Returns, 5 Years

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Average Annual Returns, 10 Years

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Average Annual Returns, Since Inception

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^[1]

Average Annual Returns, Inception Date

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Feb. 28, 1987

Class Y

Risk/Return:

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Redemption Fee (as a percentage of Amount Redeemed)

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Management Fees

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Distribution (12b-1) Fees

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none

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Total Annual Fund Operating Expenses

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Expense Example, with Redemption, 1 Year

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Expense Example, with Redemption, 3 Years

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Expense Example, with Redemption, 5 Years

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Expense Example, with Redemption, 10 Years

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SDIT SHORT DURATION GOVERNMENT FUND - CLASS A

Risk/Return:

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Annual Return 2005

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Annual Return 2006

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Annual Return 2007

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Annual Return 2008

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Annual Return 2009

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Annual Return 2010

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Annual Return 2011

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Annual Return 2012

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Annual Return 2013

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Annual Return 2014

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Fund Return Before Taxes

Average Annual Returns, 1 Year

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Average Annual Returns, 5 Years

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Average Annual Returns, 10 Years

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Average Annual Returns, Since Inception

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Average Annual Returns, Inception Date

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Feb. 17, 1987

SDIT SHORT DURATION GOVERNMENT FUND - CLASS A | After Taxes on Distributions

Risk/Return:

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Fund Return After Taxes on Distributions

Average Annual Returns, 1 Year

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Average Annual Returns, 5 Years

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Average Annual Returns, 10 Years

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Average Annual Returns, Since Inception

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SDIT SHORT DURATION GOVERNMENT FUND - CLASS A | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

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Fund Return After Taxes on Distributions and Sale of Fund Shares

Average Annual Returns, 1 Year

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Average Annual Returns, 5 Years

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Average Annual Returns, 10 Years

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Average Annual Returns, Since Inception

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[1]	Index returns are shown from February 28, 1987.