The tables below describe the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund (“Fund Shares”). You may pay other fees, such as brokerage commissions and other fees to financial intermediaries which are not reflected in the tables and examples below.

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 71% of the average value of its portfolio.

Portfolio Turnover, Rate

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71.00%

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 sell or hold all of your Fund 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. 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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The Fund seeks to achieve its investment objective by investing at least 80% of its net assets under normal circumstances in debt securities.

The Fund invests primarily in a variety of investment-grade debt securities, such as mortgage-backed securities, corporate bonds, U.S. Government securities and money market instruments. The Fund normally has a weighted average effective maturity of approximately five to ten years, but is subject to no limitation with respect to the maturities of the instruments in which it may invest. U.S. Government securities are securities that are issued or guaranteed as to principal or interest by the U.S. Government or one of its agencies or instrumentalities. Some U.S. Government securities are backed by the full faith and credit of the U.S. Government, such as U.S. Treasury bills and notes and obligations of the Government National Mortgage Association (“Ginnie Mae”). Other U.S. Government securities are neither issued by nor guaranteed by the full faith and credit of the U.S. Government, including those issued by the Federal National Mortgage Association (“Fannie Mae”) and the Federal Home Loan Mortgage Corporation (“Freddie Mac”). Fannie Mae and Freddie Mac have been operating under a conservatorship since 2008, with the Federal Housing Finance Agency acting as their conservator, and receive certain financing support from and have access to certain borrowing arrangements with the U.S. Treasury.

SSGA Funds Management, Inc. (“SSGA FM” or the “Adviser”), the investment adviser to the Fund, seeks to identify debt securities that they believe have desirable characteristics for the Fund such as:

•	attractive yields and prices;
•	the potential for capital appreciation; and/or
•	reasonable credit quality.

The Adviser may consider selling a security when one of these characteristics no longer applies, when valuation becomes excessive, or when more attractive alternatives are identified.

The Fund also may invest up to 20% of its net assets in high yield securities (also known as “junk bonds”) and, to a lesser extent, in asset-backed securities, in foreign (including emerging markets) debt securities and equity securities. The Fund may also invest in exchange-traded products (“ETPs”) that provide exposure to such investments, including ETPs that pay fees to the Adviser and its affiliates for management, marketing or other services. High yield securities are those rated BB+ through B- by S&P Global Ratings (“S&P”) or Ba1 through B3 by Moody's Investor Services, Inc. (“Moody's”) or below or of similar quality. An emerging market country is any country having an economy and market that are (or would be) considered by the World Bank to be emerging or developing, or listed in the MSCI^® Emerging Markets Index. Emerging market countries are located in regions such as Asia, Latin America, the Middle East, Southern Europe, Eastern Europe (including the former republics of the Soviet Union and the Eastern Bloc) and Africa.

The Adviser may also use various types of derivative instruments (such as options, futures, options on futures, forward contracts, interest-only swaps, interest rate swaps, index swaps, credit default swaps and structured and indexed securities) to manage yield, duration (a measure of a bond price's sensitivity to a given change in interest rates) and exposure to credit quality, and to gain or hedge exposure to certain securities, indices or market segments.

The Fund may also invest in repurchase agreements, reverse repurchase agreements, when-issued and delayed delivery securities, municipal obligations, floating rate and variable rate instruments, zero-coupon obligations, and may hold securities that are restricted as to resale. The Fund may invest in other investment companies, including exchange-traded funds (“ETFs”), to the extent permitted by applicable law (including those advised by the Adviser). The Fund also may lend its securities and may engage in active and frequent trading of its portfolio securities.

Risk [Heading]

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Principal Risks

Risk Narrative [Text Block]

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The Fund is subject to the following principal risks. You could lose money by investing in the Fund. Certain risks relating to instruments and strategies used in the management of the Fund are placed first. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund's portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund. An investment in the Fund is subject to investment risks, including possible loss of principal, is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The Fund may not achieve its investment objective. The Fund is not intended to be a complete investment program, but rather is intended for investment as part of a diversified investment portfolio. Investors should consult their own advisers as to the role of the Fund in their overall investment programs.

Market Risk: The Fund's investments are subject to changes in general economic conditions, general market fluctuations and the risks inherent in investment in securities markets. Investment markets can be volatile and prices of investments can change substantially due to various factors including, but not limited to, economic growth or recession, changes in interest rates, changes in the actual or perceived creditworthiness of issuers, and general market liquidity. The Fund is subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues, or other events could have a significant impact on the Fund and its investments.

Debt Securities Risk: The values of debt securities may increase or decrease as a result of the following: market fluctuations, changes in interest rates, actual or perceived inability or unwillingness of issuers, guarantors or liquidity providers to make scheduled principal or interest payments or illiquidity in debt securities markets; the risk of low

rates of return due to reinvestment of securities during periods of falling interest rates or repayment by issuers with higher coupon or interest rates; and/or the risk of low income due to falling interest rates. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. A rising interest rate environment may cause the value of the Fund's fixed income securities to decrease, an adverse impact on the liquidity of the Fund's fixed income securities, and increased volatility of the fixed income markets. The current low interest rate environment heightens the risks associated with rising interest rates. During periods when interest rates are at low levels, the Fund's yield can be low, and the Fund may have a negative yield (i.e., it may lose money on an operating basis). If the principal on a debt obligation is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. During periods of falling interest rates, the income received by the Fund may decline. Changes in interest rates will likely have a greater effect on the values of debt securities of longer durations. Returns on investments in debt securities could trail the returns on other investment options, including investments in equity securities.

Below Investment-Grade Securities Risk: Lower-quality debt securities (“high yield” or “junk” bonds) are considered predominantly speculative, and can involve a substantially greater risk of default than higher quality debt securities. Issuers of lower-quality debt securities may have substantially greater risk of insolvency or bankruptcy than issuers of higher-quality debt securities. They can be illiquid, and their values can have significant volatility and may decline significantly over short periods of time. Lower-quality debt securities tend to be more sensitive to adverse news about the issuer, or the market or economy in general.

Mortgage-Related and Other Asset-Backed Securities Risk: Investments in mortgage-related and other asset-backed securities are subject to the risk of significant credit downgrades, illiquidity, and defaults to a greater extent than many other types of fixed-income investments. The liquidity of mortgage-related and asset-backed securities may change over time. During periods of falling interest rates, mortgage- and asset-backed securities may be called or prepaid, which may result in the Fund having to reinvest proceeds in other investments at a lower interest rate. During periods of rising interest rates, the average life of mortgage- and asset-backed securities may extend, which may lock in a below-market interest rate, increase the security's duration and interest rate sensitivity, and reduce the value of the security. Enforcing rights against the underlying assets or collateral may be difficult, and the underlying assets or collateral may be insufficient if the issuer defaults.

U.S. Government Securities Risk: Certain U.S. government securities are supported by the full faith and credit of the United States; others are supported by the right of the issuer to borrow from the U.S. Treasury; others are supported by the discretionary authority of the U.S. government to purchase the agency's obligations; and still others are supported only by the credit of the issuing agency, instrumentality, or enterprise. Although U.S. government-sponsored enterprises such as the Federal Home Loan Mortgage Corporation (“Freddie Mac”) and the Federal National Mortgage Association (“Fannie Mae”) may be chartered or sponsored by Congress, they are not funded by Congressional appropriations, and their securities are not issued by the U.S. Treasury, are not supported by the full faith and credit of the U.S. government, and involve increased credit risks.

Counterparty Risk: The Fund will be subject to credit risk with respect to the counterparties with which the Fund enters into derivatives contracts, repurchase agreements, reverse repurchase agreements, and other transactions. If a counterparty fails to meet its contractual obligations, the Fund may be unable to terminate or realize any gain on the investment or transaction, or to recover collateral posted to the counterparty, resulting in a loss to the Fund. If the Fund holds collateral posted by its counterparty, it may be delayed or prevented from realizing on the collateral in the event of a bankruptcy or insolvency proceeding relating to the counterparty.

Currency Risk: The value of the Fund's assets may be affected favorably or unfavorably by currency exchange rates, currency exchange control regulations, and delays, restrictions or prohibitions on the repatriation of foreign currencies. Foreign currency exchange rates may have significant volatility, and changes in the values of foreign currencies against the U.S. dollar may result in substantial declines in the values of the Fund's assets denominated in foreign currencies.

Derivatives Risk: Derivative transactions can create investment leverage and may have significant volatility. It is possible that a derivative transaction will result in a much greater loss than the principal amount invested, that changes in the value of a derivative transaction may not correlate perfectly with the underlying asset, and that the Fund may

not be able to close out a derivative transaction at a favorable time or price. The counterparty to a derivatives contract may be unable or unwilling to make timely settlement payments, return the Fund's margin, or otherwise honor its obligations. A derivatives transaction may not behave in the manner anticipated by the Adviser or may not have the effect on the Fund anticipated by the Adviser.

Emerging Markets Risk: Risks of investing in emerging markets include, among others, greater political and economic instability, greater volatility in currency exchange rates, less developed securities markets, possible trade barriers, currency transfer restrictions, a more limited number of potential buyers and issuers, an emerging market country's dependence on revenue from particular commodities or international aid, less governmental supervision and regulation, unavailability of currency hedging techniques, differences in auditing and financial reporting standards, less stringent investor protection and disclosure standards, less developed public health systems, and less developed legal systems. There is also the potential for unfavorable action such as expropriation, nationalization, embargo, and acts of war. The securities of emerging market companies may trade less frequently and in smaller volumes than more widely held securities. Market disruptions or substantial market corrections may limit very significantly the liquidity of securities of certain companies in a particular country or geographic region, or of all companies in the country or region. The Fund may be unable to liquidate its positions in such securities at any time, or at a favorable price, in order to meet the Fund's obligations. These risks are generally greater for investments in frontier market countries, which typically have smaller economies or less developed capital markets than traditional emerging market countries.

Equity Investing Risk: The market prices of equity securities owned by the Fund may go up or down, sometimes rapidly or unpredictably. The value of a security may decline for a number of reasons that may directly relate to the issuer and also may decline due to general industry or market conditions that are not specifically related to a particular company. In addition, equity markets tend to move in cycles, which may cause stock prices to fall over short or extended periods of time.

Financial Sector Risk: Financial services companies are subject to extensive governmental regulation, which may limit both the amounts and types of loans and other financial commitments they can make, the interest rates and fees they can charge, the scope of their activities, the prices they can charge and the amount of capital they must maintain. Profitability is largely dependent on the availability and cost of capital funds and can fluctuate significantly when interest rates change or due to increased competition. In addition, deterioration of the credit markets generally may cause an adverse impact in a broad range of markets, including U.S. and international credit and interbank money markets generally, thereby affecting a wide range of financial institutions and markets. Certain events in the financial sector may cause an unusually high degree of volatility in the financial markets, both domestic and foreign, and cause certain financial services companies to incur large losses. Securities of financial services companies may experience a dramatic decline in value when such companies experience substantial declines in the valuations of their assets, take action to raise capital (such as the issuance of debt or equity securities), or cease operations. Credit losses resulting from financial difficulties of borrowers and financial losses associated with investment activities can negatively impact the sector. Insurance companies may be subject to severe price competition. Adverse economic, business or political developments could adversely affect financial institutions engaged in mortgage finance or other lending or investing activities directly or indirectly connected to the value of real estate.

Hedging Risk: The success of the Fund's hedging strategies will depend, in part, upon the Adviser's ability to assess correctly the degree of correlation between the performance of the instruments used in a hedging strategy and the performance of the investments being hedged. There is no guarantee that any hedging strategy used by the Fund will be successful in hedging the subject risks. It is possible that the Fund will lose money on a hedging transaction and on the asset of the Fund that was the subject of the hedge. Hedging transactions may have the effect of creating investment leverage in the Fund.

Income Risk: The Fund's income may decline due to falling interest rates or other factors. Issuers of securities held by the Fund may call or redeem the securities during periods of falling interest rates, and the Fund would likely be required to reinvest in securities paying lower interest rates. If an obligation held by the Fund is prepaid, the Fund may have to reinvest the prepayment in other obligations paying income at lower rates.

Management Risk: The Fund is actively managed. The Adviser's judgments about the attractiveness, relative value, or potential appreciation of a particular sector, security, commodity or investment strategy or as to a hedging strategy may prove to be incorrect, and may cause the Fund to incur losses. There can be no assurance that the Adviser's investment techniques and decisions will produce the desired results.

Non-U.S. Securities Risk: Non-U.S. securities (including depositary receipts) are subject to political, regulatory, and economic risks not present in domestic investments. There may be less information publicly available about a non-U.S. entity than about a U.S. entity, and many non-U.S. entities are not subject to accounting, auditing, legal and financial report standards comparable to those in the United States. Further, such entities and/or their securities may be subject to risks associated with currency controls; expropriation; changes in tax policy; greater market volatility; differing securities market structures; higher transaction costs; and various administrative difficulties, such as delays in clearing and settling portfolio transactions or in receiving payment of dividends. Securities traded on foreign markets may be less liquid (harder to sell) than securities traded domestically. Foreign governments may impose restrictions on the repatriation of capital to the U.S. In addition, to the extent that the Fund buys securities denominated in a foreign currency, there are special risks such as changes in currency exchange rates and the risk that a foreign government could regulate foreign exchange transactions. In addition, to the extent investments are made in a limited number of countries, events in those countries will have a more significant impact on the Fund. Investments in depositary receipts may be less liquid and more volatile than the underlying shares in their primary trading market.

Portfolio Turnover Risk: Frequent purchases and sales of portfolio securities may result in higher Fund expenses and may result in more significant distributions of short-term capital gains to investors, which are taxed to individuals as ordinary income.

Rapid Changes in Interest Rates Risk: Rapid changes in interest rates may cause significant requests to redeem Fund Shares, and possibly cause the Fund to sell portfolio securities at a loss to satisfy those requests.

Real Estate Sector Risk: An investment in a real property company may be subject to risks similar to those associated with direct ownership of real estate, including, by way of example, the possibility of declines in the value of real estate, losses from casualty or condemnation, and changes in local and general economic conditions, supply and demand, interest rates, environmental liability, zoning laws, regulatory limitations on rents, property taxes, and operating expenses. Some real property companies have limited diversification because they invest in a limited number of properties, a narrow geographic area, or a single type of property.

Risk of Investment in Other Pools: If the Fund invests in another pooled investment vehicle, it is exposed to the risk that the other pool will not perform as expected and is exposed indirectly to all of the risks applicable to an investment in such other pool. The investment policies of the other pool may not be the same as those of the Fund; as a result, an investment in the other pool may be subject to additional or different risks than those to which the Fund is typically subject. The Fund bears its proportionate share of the fees and expenses of any pool in which it invests. The Adviser or an affiliate may serve as investment adviser to a pool in which the Fund may invest, leading to potential conflicts of interest. It is possible that other clients of the Adviser or its affiliates will purchase or sell interests in a pool sponsored or managed by the Adviser or its affiliates at prices and at times more favorable than those at which the Fund does so.

Unconstrained Sector Risk: The Fund may invest a substantial portion of its assets within one or more economic sectors or industries, which may change from time to time. Greater investment focus on one or more sectors or industries increases the potential for volatility and the risk that events negatively affecting such sectors or industries could reduce returns, potentially causing the value of the Fund's Shares to decrease, perhaps significantly.

U.S. Treasury Obligations Risk: U.S. Treasury obligations may differ from other fixed income securities in their interest rates, maturities, times of issuance and other characteristics. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund's U.S. Treasury obligations to decline.

Valuation Risk: Some portfolio holdings, potentially a large portion of the Fund's investment portfolio, may be valued on the basis of factors other than market quotations. This may occur more often in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations

are not readily available. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. Portfolio holdings that are valued using techniques other than market quotations, including “fair valued” securities, may be subject to greater fluctuation in their valuations from one day to the next than if market quotations were used. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. Investors who purchase or redeem Fund Shares on days when the Fund is holding fair-valued investments may receive fewer or more shares or lower or higher redemption proceeds than they would have received if the Fund had not fair-valued the holding(s) or had used a different valuation methodology.

Risk Lose Money [Text]

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You could lose money by investing in the Fund.

Risk Not Insured Depository Institution [Text]

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An investment in the Fund is subject to investment risks, including possible loss of principal, is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.

Bar Chart and Performance Table [Heading]

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Performance

Performance Narrative [Text Block]

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The bar chart and table below provide some indication of the risks of investing in the Fund by illustrating the variability of the Fund's returns from year-to-year and by showing how the Fund's average annual returns for the periods indicated compared with those of a broad measure of market performance. The Fund's past performance does not necessarily indicate how the Fund will perform in the future. Current performance information for the Fund is available toll free by calling (800)-242-0134 or by visiting our website at www.ssga.com.

Performance Information Illustrates Variability of Returns [Text]

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Performance Availability Phone [Text]

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(800)-242-0134

Performance Availability Website Address [Text]

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www.ssga.com

Performance Past Does Not Indicate Future [Text]

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The Fund's past performance does not necessarily indicate how the Fund will perform in the future.

Bar Chart [Heading]

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Annual Total Returns (years ended 12/31)

Bar Chart Closing [Text Block]

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Highest Quarterly Return: 4.77% (Q2, 2020)
Lowest Quarterly Return: -3.07% (Q1, 2021)

Performance Table Heading

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Average Annual Total Returns (for periods ended 12/31/21)

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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After-tax returns depend on an investor's tax situation and may differ from those shown above, and after-tax returns are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).

Performance Table Explanation after Tax Higher

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The returns after taxes can exceed the returns before taxes due to an assumed tax benefit for a shareholder from realizing a capital loss on a sale of Fund shares.

Performance Table Narrative

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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. After-tax returns depend on an investor's tax situation and may differ from those shown above, and after-tax returns are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). The returns after taxes can exceed the returns before taxes due to an assumed tax benefit for a shareholder from realizing a capital loss on a sale of Fund shares.

The returns for certain periods would have been lower without the effect of a contractual fee waiver and/or reimbursement.

ELFUN INCOME FUND | Elfun Income Fund

Risk/Return:

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Maximum Sales Charge (Load) Imposed On Purchases (as a percentage of offering price)

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none

Maximum Deferred Sales Charge (Load) (as a percentage of the net asset value)

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none

Management Fees

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