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(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund’s investment objective is high current income. Capital appreciation is the Fund’s secondary objective.
Expense [Heading] rr_ExpenseHeading FUND FEES & EXPENSES
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The following table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund*. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table.
The Fund does not impose a sales charge, a redemption fee or an exchange fee.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses(expenses that you pay each year as a percentage of the value of your investment)* [1]
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The 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. The example does not take into account brokerage commissions and other fees to financial intermediaries that you may pay on your purchases and sales of shares of the Fund. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] 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 for you if your 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 its most recently ended fiscal year, the Fund’s portfolio turnover rate was 48% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 48.00%
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCEPrincipal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the Fund will invest substantially all of its assets, and may invest up to 100% of its assets, in high income securities (“High-Income Securities”). High-Income Securities are fixed-income securities that Loomis Sayles believes have the potential to generate relatively high levels of current income. High-Income Securities are often rated below investment-grade (below investment-grade securities are sometimes referred to as “high-yield securities” or “junk bonds”). Below investment-grade fixed-income securities are rated below investment-grade quality (i.e., none of the three major rating agencies (Moody’s Investors Service, Inc., Fitch Investor Services, Inc. or S&P’s Global Ratings) have rated the securities in one of their respective top four rating categories). The Fund’s fixed-income securities investments may include unrated securities (securities that are not rated by a rating agency) if Loomis Sayles determines that the securities
are of comparable quality to rated securities that the Fund may purchase. The Fund may invest approximately 20% of its assets in investment-grade fixed-income securities. The Fund may invest a portion of its assets in senior floating-rate loans made to U.S. and foreign borrowers. A significant portion of the securities purchased by the Fund may be issued by smaller-capitalization companies. There is no minimum rating for debt in which the Fund may invest.
Under normal market conditions, the Fund may invest up to 40% of its assets in foreign securities, including emerging market securities. The Fund may invest without limit in obligations of supranational entities (e.g., the World Bank). Although certain securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if the issuer is included in the U.S. fixed-income indices published by Bloomberg. The Fund may also invest in derivatives, including swaps (including credit default swaps, in which one party agrees to make periodic payments to a counterparty in exchange for the right to receive a payment in the event of a default of the underlying reference security), purchasing or selling options or futures contracts to manage interest rate and credit risk.
The Fund’s investments may include, among other things, corporate debt securities, U.S. government obligations, U.S. dollar denominated foreign securities, zero-coupon and pay-in-kind securities, loan assignments and participations, delayed funding loans and revolving credit facilities, commercial paper, mortgage-backed securities, collateralized mortgage obligations, mortgage dollar rolls, collateralized debt and loan obligations and other asset-backed securities, securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”), other privately placed investments such as private credit investments, when-issued securities, municipal bonds, repurchase agreements, debt-linked and equity-linked securities, convertible securities, preferred shares and illiquid securities.
In deciding which High-Income Securities to buy and sell, Loomis Sayles will consider, among other things, the financial strength of the issuer, yield, coupon rate, current interest rates, current valuations and comparisons of the level of risk associated with particular investments with Loomis Sayles’ expectations concerning the potential return of those types of investments. As part of its investment approach, Loomis Sayles generally seeks fixed-income securities of issuers whose credit profiles Loomis Sayles believes have the potential to stabilize or improve. With respect to investments in foreign securities, Loomis Sayles will consider the global economic environment, and the economic environment of the relevant country, taking into account factors such as GDP growth, inflation and other economic conditions, monetary policy, fiscal policy, leadership and social stability.
Loomis Sayles may invest significantly in securities whose price Loomis Sayles believes is more sensitive to events related to the underlying issuer than to changes in general interest rates or overall market default rates.
Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund and an additional index that represents the market sectors in which the Fund primarily invests. Updated performance information is available online at www.loomissayles.com and/or by calling the Fund toll-free at 800-633-3330.
The bar chart and the table do not reflect any “wrap fees” that a participant in a “wrap” program may be required to pay to a program’s sponsor. See the section “Management” in the Statutory Prospectus. A “wrap fee” will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund and an additional index that represents the market sectors in which the Fund primarily invests.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-633-3330
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.loomissayles.com
Bar Chart [Heading] rr_BarChartHeading Total Returns for Institutional Class Shares
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes Index performance 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 Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return:

Second Quarter 2020, 9.87%

Lowest Quarterly Return:

First Quarter 2020, -12.05%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns(for the periods ended December 31, 2023)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
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. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. Index performance reflects no deduction for fees, expenses or taxes.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk is the risk that the issuer or guarantor of a fixed-income security in which the Fund invests, or the counterparty to a derivative or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. As a result, the Fund may sustain losses or be unable or delayed in its ability to realize gains. Senior loans and other floating rate securities that are rated below investment-grade are considered predominantly speculative with respect to the ability of the issuer to make timely principal and interest payments.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Below Investment-Grade Fixed-Income Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Below Investment-Grade Fixed-Income Securities Risk is the risk that the Fund’s investments in below investment-grade fixed-income securities may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment-grade fixed-income securities.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund’s investments when it needs to dispose of them. Markets may become illiquid quickly. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. During times of market turmoil, there may be no buyers or sellers for securities in certain asset classes. Securities acquired in
a private placement, such as Rule 144A securities and privately negotiated credit and other investments, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. In other circumstances, liquid investments may become illiquid. Liquidity issues may also make it difficult to value the Fund’s investments. The Fund may invest in liquid investments that become illiquid due to financial distress, or geopolitical events such as sanctions, trading halts or wars.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk is the risk that the market value of the Fund’s investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund’s investments, such as management performance, financial condition and demand for the issuers’ goods and services.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Interest Rate Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk is the risk that the value of the Fund’s investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. The values of zero-coupon securities, pay-in-kind bonds and securities with longer maturities are generally more sensitive to fluctuations in interest rates than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund’s ability to sell them, negatively impacting the performance of the Fund. Potential future changes in government and/or central bank monetary policy and action may also affect the level of interest rates.
Recently, there have been inflationary price movements, which have caused the fixed income securities markets to experience heightened levels of interest volatility and liquidity risk. Monetary policy measures have in the past, and may in the future, exacerbate risks associated with rising interest rates.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Currency Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Currency Risk is the risk that the value of the Fund’s investments will fall as a result of changes in exchange rates. Loomis Sayles may elect not to hedge currency risk or may hedge imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk is the risk associated with the increasing dependence of the Fund, its service providers, and other market participants on complex information technology and communications systems. Such systems are subject to a number of different threats and risks that could adversely affect the Fund and its shareholders. Cybersecurity and other operational and technology issues may result in financial losses to the Fund and its shareholders.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk is the risk that the value of the Fund’s derivative investments such as options, futures transactions and swap transactions will fall, for example, because of changes in the value of the underlying reference instruments, pricing difficulties or lack of correlation with the underlying investments. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. There is also the risk that the Fund may be unable to terminate or sell a derivative position at an advantageous time or price. The Fund’s derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund. This risk is greater for uncleared swaps and other over-the-counter (“OTC”) traded derivatives. Investing in derivatives gives rise to other risks, such as leverage risk, liquidity risk, credit/counterparty risk, interest rate risk and market/issuer risk. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Emerging Markets Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk is the risk that the Fund’s investments in emerging markets may face greater foreign securities risk. Emerging markets investments are subject to greater risks arising from political or economic instability, war, nationalization or confiscatory taxation, currency exchange or repatriation restrictions, sanctions by other countries (such as the United States or the European Union), new or inconsistent government treatment of or restrictions on issuers and instruments, and an issuer’s unwillingness or inability to make dividend, principal or interest payments on its securities. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Equity Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Equity Securities Risk is the risk that the value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Foreign Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Foreign Securities Risk is the risk that the value of the Fund’s foreign investments will fall as a result of foreign political, social, economic, environmental, credit, informational or currency changes or other issues relating to foreign investing generally. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. The Fund’s investments in foreign securities may be subject to foreign withholding or other taxes, which would decrease the yield on those securities.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Inflation/Deflation Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Inflation/Deflation Risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. As inflation increases, the real value of the Fund’s portfolio could decline. Inflation rates may change frequently and drastically. The Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors. Recently, inflation rates in the United States and elsewhere have been increasing. There can be no assurance that this trend will not continue or that efforts to slow or reverse inflation will not harm the economy and asset values. Deflation risk is the risk that prices throughout the economy decline over time - the opposite of inflation. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund’s portfolio.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Large Investor Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Large Investor Risk is the risk associated with ownership of shares of the Fund that may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund’s expenses.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk is the risk associated with securities or investment practices (e.g., borrowing and the use of certain derivatives) that multiply small index, market or asset price movements into larger changes in value. Use of derivative instruments (such as futures and forward currency contracts) may involve leverage. When a derivative is used as a hedge against an offsetting position that the Fund also holds, any gains generated by the derivative should be substantially offset by losses on the hedged instrument, and vice versa. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on the Fund’s returns, and may lead to significant losses if investments are not successful.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk is the risk that Loomis Sayles’ investment techniques will be unsuccessful and cause the Fund to incur losses.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Mortgage-Related and Asset-Backed Securities Risk is the risk associated with the mortgages and assets underlying the securities, as well as the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that a rise in interest rates will extend the life of a mortgage-related or asset-backed security beyond the expected prepayment time, typically reducing the security’s value, which is called extension risk. The Fund may also incur a loss when there is a prepayment of securities that were purchased at a premium. It also includes risks associated with investing in the mortgages underlying the mortgage-backed securities. The Fund’s investments in other asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets. The Fund’s investments in mortgage-related and other asset-backed securities are also subject to the risks associated with investments in fixed-income securities generally (e.g., credit/counterparty, liquidity, inflation and valuation risks).
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Small-Capitalization Companies Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Small-Capitalization Companies Risk is the risk that the Fund’s investments may be subject to more abrupt price movements, limited markets, increased volatility and less liquidity than investments in larger, more established companies, which could adversely affect the value of the portfolio.
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.53% [2]
Past 5 Years rr_AverageAnnualReturnYear05 1.10% [2]
Past 10 Years rr_AverageAnnualReturnYear10 1.81% [2]
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Bloomberg U.S. Corporate High Yield Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 13.44%
Past 5 Years rr_AverageAnnualReturnYear05 5.37%
Past 10 Years rr_AverageAnnualReturnYear10 4.60%
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Institutional Class  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Total Annual Fund Operating Expenses rr_ExpensesOverAssets none
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 none
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 none
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 none
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 none
Annual Return 2014 rr_AnnualReturn2014 4.59%
Annual Return 2015 rr_AnnualReturn2015 (3.13%)
Annual Return 2016 rr_AnnualReturn2016 15.85%
Annual Return 2017 rr_AnnualReturn2017 8.39%
Annual Return 2018 rr_AnnualReturn2018 (2.08%)
Annual Return 2019 rr_AnnualReturn2019 13.01%
Annual Return 2020 rr_AnnualReturn2020 9.24%
Annual Return 2021 rr_AnnualReturn2021 4.32%
Annual Return 2022 rr_AnnualReturn2022 (12.86%)
Annual Return 2023 rr_AnnualReturn2023 10.81%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 9.87%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.05%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Past 1 Year rr_AverageAnnualReturnYear01 10.81%
Past 5 Years rr_AverageAnnualReturnYear05 4.46%
Past 10 Years rr_AverageAnnualReturnYear10 4.48%
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Institutional Class | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 7.50%
Past 5 Years rr_AverageAnnualReturnYear05 1.57%
Past 10 Years rr_AverageAnnualReturnYear10 1.74%
(Loomis Sayles Funds I) | (Loomis Sayles High Income Opportunities Fund) | Institutional Class | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 6.30%
Past 5 Years rr_AverageAnnualReturnYear05 2.20%
Past 10 Years rr_AverageAnnualReturnYear10 2.23%
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading INVESTMENT OBJECTIVE
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund’s investment objective is to seek a high level of current income consistent with capital preservation.
Expense [Heading] rr_ExpenseHeading FUND FEES & EXPENSES
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
The following table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the Fund*. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in this table.
The Fund does not impose a sales charge, a redemption fee or an exchange fee.
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses(expenses that you pay each year as a percentage of the value of your investment)* [3]
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
The 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. The example does not take into account brokerage commissions and other fees to financial intermediaries that you may pay on your purchases and sales of shares of the Fund. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] 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 for you if your 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 its most recently ended fiscal year, the Fund’s portfolio turnover rate was 106% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 106.00%
Strategy [Heading] rr_StrategyHeading INVESTMENTS, RISKS AND PERFORMANCEPrincipal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in a diversified portfolio of securitized assets, such as mortgage-backed and other asset-backed securities. The Fund may invest in asset-backed securities of any type, including residential and commercial asset-backed securities, asset-backed securities related to automobiles, credit cards, home equity loans, manufactured housing, utilities, and other miscellaneous asset-backed securities. The Fund may only buy securities that are rated investment-grade at the time of purchase by at least one of the three major rating agencies (Moody’s Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) or, if unrated, are determined by Loomis Sayles to be of comparable quality. It is expected that a majority of the Fund’s securities will be rated AAA or Aaa by at least one of the rating agencies at the time of
purchase. The Fund may continue to hold securities that are downgraded in credit rating subsequent to their purchase if Loomis Sayles believes it would be advantageous to do so.
The Fund may, without limitation, seek to obtain market exposure to the securities in which it primarily invests by entering into a series of purchase and sale contracts (including on a “to be announced” basis) or by using investment techniques such as buybacks and dollar rolls.
Loomis Sayles uses a bottom-up, fundamental research process to select individual securities for the Fund. The decision to buy or sell a particular security is largely driven by Loomis Sayles’ view of the fundamentals of the issue compared to the prevailing market valuation, which may be higher (suggesting a potential sell decision) or lower (suggesting a potential buy decision). Loomis Sayles also may seek to construct a portfolio with risk characteristics similar, but not identical to, certain of the securities in the Bloomberg U.S. Securitized Bond Index (the “Index”). Examples of typical risk characteristics that Loomis Sayles might consider include average life, credit quality, effective duration, yield curve exposure and sector exposure. The portfolio will not necessarily exhibit similarities with the Index for some or all risk characteristics. It is currently anticipated that the Fund’s effective duration will be within +/- 1 year of the effective duration of the Index.
In deciding which securities to buy and sell, Loomis Sayles will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, Loomis Sayles’ expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with Loomis Sayles’ expectations concerning the potential return of those investments.
The Fund’s investments may also include, among other things, the following: fixed and floating-rate instruments, mortgage pass-through securities issued or guaranteed by agencies or instrumentalities of the U.S. government, collateralized mortgage obligations, commercial mortgage-backed securities, mortgage-related asset-backed securities, other collateralized asset-backed securities, securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A Securities”), other privately placed investments such as private credit instruments, U.S. government securities, corporate debt securities, zero-coupon securities, step coupon securities, commercial paper, structured notes, other mortgage-related securities (including adjustable rate mortgage securities, stripped mortgage-backed securities and mortgage dollar rolls), when-issued securities and repurchase agreements. The Fund may also invest in options, futures and swaps (including credit default swaps, in which one party agrees to make periodic payments to a counterparty in exchange for the right to receive a payment in the event of a default of the underlying reference security).
The Fund may also engage in active and frequent trading of securities. Frequent trading may produce a high level of taxable gains, including short-term capital gains taxable as ordinary income, as well as increased trading costs, which may lower the Fund’s return.
Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund and an additional index that represents the market sectors in which the Fund primarily invests. Updated performance information is available online at www.loomissayles.com and/or by calling the Fund toll-free at 800-633-3330.
The bar chart and the table do not reflect any “wrap fees” that a participant in a “wrap” program may be required to pay to a program’s sponsor. See the section “Management” in the Statutory Prospectus. A “wrap fee” will reduce your return.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund and an additional index that represents the market sectors in which the Fund primarily invests.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-633-3330
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.loomissayles.com
Bar Chart [Heading] rr_BarChartHeading Total Returns for Institutional Class Shares
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes Index performance 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 Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return:

Fourth Quarter 2023, 7.10%

Lowest Quarterly Return:

First Quarter 2022, -4.89%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns(for the periods ended December 31, 2023)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
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. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. Index performance reflects no deduction for fees, expenses or taxes.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk is the risk that the issuer or guarantor of a fixed-income security in which the Fund invests, or the counterparty to a derivative or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. As a result, the Fund may sustain losses or be unable or delayed in its ability to realize gains.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Events that may lead to increased redemptions, such as market disruptions or increases in interest rates, may also negatively impact the liquidity of the Fund’s investments when it needs to dispose of them. Markets may become illiquid quickly. If the Fund is forced to sell its investments at an unfavorable time and/or under adverse conditions in order to meet redemption requests, such sales could negatively affect the Fund. During times of market turmoil, there may be no buyers or sellers for securities in certain asset classes. Securities acquired in a private placement, such as Rule 144A securities and privately negotiated credit and other investments, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. In other circumstances, liquid investments may become illiquid. Liquidity issues may also make it difficult to value the Fund’s investments. The Fund may invest in liquid investments that become illiquid due to financial distress, or geopolitical events such as
sanctions, trading halts or wars.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk is the risk that the market value of the Fund’s investments will move up and down, sometimes rapidly and unpredictably, based upon overall market and economic conditions, as well as a number of reasons that directly relate to the issuers of the Fund’s investments, such as management performance, financial condition and demand for the issuers’ goods and services.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Interest Rate Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk is the risk that the value of the Fund’s investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. The values of zero-coupon securities and securities with longer maturities are generally more sensitive to fluctuations in interest rates than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund’s ability to sell them, negatively impacting the performance of the Fund. Potential future changes in government monetary policy may affect the level of interest rates.
Recently, there have been inflationary price movements, which have caused the fixed income securities markets to experience heightened levels of interest volatility and liquidity risk. Monetary policy measures have in the past, and may in the future, exacerbate risks associated with rising interest rates.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk is the risk associated with the increasing dependence of the Fund, its service providers, and other market participants on complex information technology and communications systems. Such systems are subject to a number of different threats and risks that could adversely affect the Fund and its shareholders. Cybersecurity and other operational and technology issues may result in financial losses to the Fund and its shareholders.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk is the risk that the value of the Fund’s derivative investments such as structured notes, options, futures transactions and swap transactions will fall, for example, because of changes in the value of the underlying reference instruments, pricing difficulties or lack of correlation with the underlying investments. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. There is also the risk that the Fund may be unable to terminate or sell a derivative position at an advantageous time or price. The Fund’s derivative counterparties may experience financial difficulties or otherwise be unwilling or unable to honor their obligations, possibly resulting in losses to the Fund. This risk is greater for uncleared swaps and other over-the-counter (“OTC”) traded derivatives. Investing in derivatives gives rise to other risks, such as leverage risk, liquidity risk, credit/counterparty risk, interest rate risk and market/issuer risk. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Inflation/Deflation Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Inflation/Deflation Risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. As inflation increases, the real value of the Fund’s portfolio could decline. Inflation rates may change frequently and drastically. The Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors. Recently, inflation rates in the United States and elsewhere have been increasing. There can be no assurance that this trend will not continue or that efforts to slow or reverse inflation will not harm the economy and asset values. Deflation risk is the risk that prices throughout the economy decline over time - the opposite of inflation. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund’s portfolio.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Large Investor Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Large Investor Risk is the risk associated with ownership of shares of the Fund that may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund’s expenses.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk is the risk associated with securities or investment practices (e.g., borrowing and the use of certain derivatives) that multiply small index, market or asset price movements into larger changes in value. Use of derivative instruments (such as futures and forward currency contracts) may involve leverage. When a derivative is used as a hedge against an offsetting position that the Fund also holds, any gains generated by the derivative should be substantially offset by losses on the hedged instrument, and vice versa. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on the Fund’s returns, and may lead to significant losses if investments are not successful.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk is the risk that Loomis Sayles’ investment techniques will be unsuccessful and cause the Fund to incur losses.
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Mortgage-Related and Asset-Backed Securities Risk is the risk associated with the mortgages and assets underlying the securities, as well as the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that a rise in interest rates will extend the life of a mortgage-related or asset-backed security beyond the expected prepayment time, typically reducing the security’s value, which is called extension risk. The Fund may also incur a loss
when there is a prepayment of securities that were purchased at a premium. It also includes risks associated with investing in the mortgages underlying the mortgage-backed securities. The Fund’s investments in other asset-backed securities are subject to risks similar to those associated with mortgage-related securities, as well as additional risks associated with the nature of the assets and the servicing of those assets. The Fund’s investments in mortgage-related and other asset-backed securities are also subject to the risks associated with investments in fixed-income securities generally (e.g., credit/counterparty, liquidity, inflation and valuation risks).
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.53% [4]
Past 5 Years rr_AverageAnnualReturnYear05 1.10% [4]
Past 10 Years rr_AverageAnnualReturnYear10 1.81% [4]
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Bloomberg U.S. Securitized Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.08%
Past 5 Years rr_AverageAnnualReturnYear05 0.37%
Past 10 Years rr_AverageAnnualReturnYear10 1.43%
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Institutional Class  
Prospectus: rr_ProspectusTable  
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets none
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets none
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets none
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 none
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 none
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 none
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 none
Annual Return 2014 rr_AnnualReturn2014 6.45%
Annual Return 2015 rr_AnnualReturn2015 1.98%
Annual Return 2016 rr_AnnualReturn2016 3.10%
Annual Return 2017 rr_AnnualReturn2017 3.40%
Annual Return 2018 rr_AnnualReturn2018 2.48%
Annual Return 2019 rr_AnnualReturn2019 6.80%
Annual Return 2020 rr_AnnualReturn2020 4.67%
Annual Return 2021 rr_AnnualReturn2021 0.64%
Annual Return 2022 rr_AnnualReturn2022 (11.83%)
Annual Return 2023 rr_AnnualReturn2023 7.01%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.10%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (4.89%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2022
Past 1 Year rr_AverageAnnualReturnYear01 7.01%
Past 5 Years rr_AverageAnnualReturnYear05 1.20%
Past 10 Years rr_AverageAnnualReturnYear10 2.33%
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Institutional Class | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 4.54%
Past 5 Years rr_AverageAnnualReturnYear05 (1.18%)
Past 10 Years rr_AverageAnnualReturnYear10 none
(Loomis Sayles Funds I) | (Loomis Sayles Securitized Asset Fund) | Institutional Class | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 4.09%
Past 5 Years rr_AverageAnnualReturnYear05 (0.05%)
Past 10 Years rr_AverageAnnualReturnYear10 0.78%
[1]
* The amounts shown in the table are 0.00% to reflect the fact that the Fund does not pay any advisory, administration or distribution and service fees, and that Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has agreed to pay certain expenses of the Fund. You should be aware, however, that shares of the Fund are available only to institutional investment advisory clients of Loomis Sayles and Natixis Advisors, LLC (“Natixis Advisors”) and to participants in certain approved “wrap fee” programs sponsored by broker-dealers and investment advisers that may be affiliated or unaffiliated with the Fund, Loomis Sayles or Natixis Advisors. The institutional investment advisory clients of Loomis Sayles and Natixis Advisors pay Loomis Sayles or Natixis Advisors a fee for their investment advisory services, while participants in “wrap fee” programs pay a “wrap” fee to the program’s sponsor. The “wrap fee” program sponsors in turn pay fees to Natixis Advisors. Participants in “wrap fee” programs should carefully read the wrap fee brochure provided to them by their program’s sponsor. The brochure is required to include information about the fees charged by the “wrap fee” program sponsor and the fees paid by such sponsor to Natixis Advisors. Investors pay no additional fees or expenses to purchase shares of the Fund. Investors will, however, indirectly pay a proportionate share of those costs, such as brokerage commissions, taxes and extraordinary expenses that are borne by the Fund through a reduction in their net asset value. See the section “Management” in the Statutory Prospectus.
[2]
1 Effective February 1, 2024, the Fund’s primary broad-based performance index changed to the Bloomberg U.S. Aggregate Bond Index. The Bloomberg U.S. Aggregate Bond Index is a broad-based securities market index that represents the overall market applicable to the Fund. The Fund will retain the Bloomberg U.S. Corporate High Yield Bond Index as its additional benchmark for performance comparison.
[3]
* The amounts shown in the table are 0.00% to reflect the fact that the Fund does not pay any advisory, administration or distribution and service fees, and that Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has agreed to pay certain expenses of the Fund. You should be aware, however, that shares of the Fund are available only to institutional investment advisory clients of Loomis Sayles and Natixis Advisors, LLC (“Natixis Advisors”) and to participants in certain approved “wrap fee” programs sponsored by broker-dealers and investment advisers that may be affiliated or unaffiliated with the Fund, Loomis Sayles or Natixis Advisors. The institutional investment advisory clients of Loomis Sayles and Natixis Advisors pay Loomis Sayles or Natixis Advisors a fee for their investment advisory services, while participants in “wrap fee” programs pay a “wrap” fee to the program’s sponsor. The “wrap fee” program sponsors in turn pay fees to Natixis Advisors. Participants in “wrap fee” programs should carefully read the wrap fee brochure provided to them by their program’s sponsor. The brochure is required to include information about the fees charged by the “wrap fee” program sponsor and the fees paid by such sponsor to Natixis Advisors. Investors pay no additional fees or expenses to purchase shares of the Fund. Investors will, however, indirectly pay a proportionate share of those costs, such as brokerage commissions, taxes and extraordinary expenses that are borne by the Fund through a reduction in their net asset value. See the section “Management” in the Statutory Prospectus.
[4]
1 Effective February 1, 2024, the Fund’s primary broad-based performance index changed to the Bloomberg U.S. Aggregate Bond Index. The Bloomberg U.S. Aggregate Bond Index is a broad-based securities market index that represents the overall market applicable to the Fund. The Fund will retain the Bloomberg U.S. Securitized Bond Index as its additional benchmark for performance comparison.