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(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks high current income plus the opportunity for capital appreciation to produce a high total return.
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. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 70 of the Prospectus, in Appendix A to the Prospectus and on page 130 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees(fees paid directly from your investment)
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)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination April 30, 2025
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Other expenses for Class T shares are estimated for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. 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:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If shares are not redeemed:
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 40% of the average value of its portfolio. 
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 40.00%
Strategy [Heading] rr_StrategyHeading Investments, Risks and PerformancePrincipal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal circumstances, the Fund will invest at least 80% of its assets in below investment grade fixed-income securities (commonly known as “junk bonds”). Below investment grade fixed-income securities are rated below investment grade quality (i.e., none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or S&P Global Ratings (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. There is no minimum rating for the securities in which the Fund may invest. The Fund may invest up to 30% of its assets in U.S. dollar-denominated foreign fixed-income securities, including those in emerging markets. 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 Adviser performs its own extensive credit analysis to determine the creditworthiness and potential for capital appreciation of a security. The Fund’s management minimizes both market timing and interest rate forecasting. Instead, it uses a strategy based on gaining a thorough understanding of industry and company dynamics as well as individual security characteristics such as issuer debt and debt maturity schedules, earnings prospects, responsiveness to changes in interest rates, experience and perceived strength of management, borrowing requirements and liquidation value, market price in relation to cash flow, interest and dividends.
In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.
In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser employs a selection strategy that focuses on a value-driven, bottom-up approach to identify securities that provide an opportunity for both generous yields and capital appreciation. The Adviser analyzes an individual company’s potential for positive financial news to determine if it has growth potential. Examples of positive financial news include an upward turn in the business cycle, improvement in cash flows, rising profits or the awarding of new contracts. The Adviser emphasizes in-depth credit analysis, appreciation potential and diversification in its bond selection. Each bond is evaluated to assess the ability of its issuer to pay interest and, ultimately, principal (which helps the Fund generate an ongoing flow of income). The Adviser also assesses a bond’s relation to market conditions within its industry and favors bonds whose prices may benefit from positive business developments. The Adviser seeks to diversify the Fund’s holdings to reduce the inherent risk in below investment grade fixed-income securities.
In connection with its principal investment strategies, the Fund may also invest in structured notes, collateralized loan obligations, zero-coupon securities, pay-in-kind securities, convertible 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, and futures, forward contracts and swaps (including credit default swaps) for hedging and investment purposes. The Fund may from time to time satisfy the 80% test above by obtaining investment exposure to below investment grade fixed-income securities through investments in these derivative instruments. Except as provided above or as required by applicable law, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading] rr_RiskHeading Principal Investment Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The bar chart and table shown below provide some 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, ten-year, and life-of-class periods (as applicable) 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 for Class C shares includes the automatic conversion to Class A shares after eight years, where applicable. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478. 
The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return. To the extent that a class of shares was subject to the waiver or reimbursement of certain expenses during a period, had such expenses not been waived or reimbursed during the period, total returns would have been lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table shown below provide some 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, ten-year, and life-of-class periods (as applicable) 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 800-225-5478
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress im.natixis.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T 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.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return:

Second Quarter 2020, 11.39%
Lowest Quarterly Return:
First Quarter 2020, -14.16%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns(for the periods ended December 31, 2023)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund’s other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.
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. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Risk Lose Money [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Risk Not Insured Depository Institution [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock Fund shares are not bank deposits and are not guaranteed, endorsed or insured by the Federal Deposit Insurance Corporation or any other government agency, and are subject to investment risks, including possible loss of the principal invested.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Below Investment Grade Fixed-Income Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Below Investment Grade Fixed-Income Securities Risk: The Fund’s investments in below investment grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, 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. The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearinghouses, such as the performance guarantee given by a central clearinghouse, are not available in connection with over-the-counter (“OTC”) derivatives transactions, such as foreign currency transactions. For centrally cleared derivatives, such as cleared swaps, futures and many options, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearinghouse itself.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk: 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Interest Rate Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk: 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 and pay-in-kind bonds may be 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk: 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. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. 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 equity 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. Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Convertible Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Convertible Securities Risk: Convertible securities have investment characteristics of both equity and debt securities. Investments in convertible securities are subject to the usual risks associated with debt instruments, such as interest rate risk and credit risk. Convertible securities also react to changes in the value of the common stock into which they convert, and are thus subject to many of the same risks as investing in common stock. The Fund may convert a convertible security at an inopportune time, which may decrease the Fund’s return.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures, forward contracts, structured notes and swaps (including credit default swaps)) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur
losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives, such as futures, forward contracts, structured notes and swaps (including credit default swaps) involves other risks, such as credit/counterparty risk relating to the other party to a derivative contract (which is greater for forward currency contracts, uncleared swaps and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than any amounts paid or margin transferred to initiate derivatives positions. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Emerging Markets Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Foreign Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Large Investor Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Large Investor Risk: Ownership of shares of the Fund 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk: Leverage 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. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity, inflation and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, 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 also may incur a loss when there is a prepayment of securities that were purchased at a premium. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.53% [1]
Past 5 Years rr_AverageAnnualReturnYear05 1.10% [1]
Past 10 Years rr_AverageAnnualReturnYear10 1.81% [1]
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.25%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [2]
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [3]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.57% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.37%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.42% [5],[6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 518
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 801
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,105
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,966
Past 1 Year rr_AverageAnnualReturnYear01 4.74%
Past 5 Years rr_AverageAnnualReturnYear05 2.42%
Past 10 Years rr_AverageAnnualReturnYear10 2.72%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [3]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.57% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.12%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.42% [5],[6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 273
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 624
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,101
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,227
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 173
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 624
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,101
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,227
Past 1 Year rr_AverageAnnualReturnYear01 7.94%
Past 5 Years rr_AverageAnnualReturnYear05 2.58%
Past 10 Years rr_AverageAnnualReturnYear10 2.57%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [3]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 1.24% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.79%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 1.14% [5],[6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.65%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 66
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 452
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 863
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,011
Past 1 Year rr_AverageAnnualReturnYear01 9.85%
Past 5 Years rr_AverageAnnualReturnYear05 3.64%
Since Inception rr_AverageAnnualReturnSinceInception 3.42%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class N | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Since Inception rr_AverageAnnualReturnSinceInception 1.29% [1]
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class N | Bloomberg U.S. Corporate High-Yield Bond Index  
Prospectus: rr_ProspectusTable  
Since Inception rr_AverageAnnualReturnSinceInception 4.77%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [3]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.57% [4],[7]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.37%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.42% [5],[6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 344
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 633
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 942
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,820
Past 1 Year rr_AverageAnnualReturnYear01 6.78%
Past 5 Years rr_AverageAnnualReturnYear05 2.82%
Past 10 Years rr_AverageAnnualReturnYear10 2.93%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.55% [3]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.58% [4]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.13%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.43% [5],[6]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.70%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 72
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 316
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 581
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,336
Annual Return 2014 rr_AnnualReturn2014 4.55%
Annual Return 2015 rr_AnnualReturn2015 (6.22%)
Annual Return 2016 rr_AnnualReturn2016 15.04%
Annual Return 2017 rr_AnnualReturn2017 7.80%
Annual Return 2018 rr_AnnualReturn2018 (3.21%)
Annual Return 2019 rr_AnnualReturn2019 12.52%
Annual Return 2020 rr_AnnualReturn2020 8.19%
Annual Return 2021 rr_AnnualReturn2021 3.15%
Annual Return 2022 rr_AnnualReturn2022 (13.47%)
Annual Return 2023 rr_AnnualReturn2023 10.13%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 11.39%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (14.16%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Past 1 Year rr_AverageAnnualReturnYear01 10.13%
Past 5 Years rr_AverageAnnualReturnYear05 3.65%
Past 10 Years rr_AverageAnnualReturnYear10 3.48%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 6.63%
Past 5 Years rr_AverageAnnualReturnYear05 1.22%
Past 10 Years rr_AverageAnnualReturnYear10 1.19%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles High Income Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.89%
Past 5 Years rr_AverageAnnualReturnYear05 1.77%
Past 10 Years rr_AverageAnnualReturnYear10 1.68%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund’s investment goal is long-term growth of capital.
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. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 70 of the Prospectus, in Appendix A to the Prospectus, and on page 130 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Funds Complex.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees(fees paid directly from your investment)
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)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination April 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the date noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. 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:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If shares are not redeemed:
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 5% of the average value of its portfolio. 
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 5.00%
Strategy [Heading] rr_StrategyHeading Investments, Risks and PerformancePrincipal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal circumstances, the Fund will invest primarily in equity securities, including common stocks and depositary receipts. The Fund will primarily invest in securities of companies that maintain their principal place of business or conduct their principal business activities outside the U.S., companies that have their securities traded on non-U.S. exchanges or companies that have been formed under the laws of non-U.S. countries. The Fund will invest in securities that provide exposure to no fewer than three countries outside the U.S. including companies located in emerging markets. Notwithstanding the foregoing, the Adviser does not consider a security to be foreign if it is included in the U.S. equity indices published by S&P Global Ratings or Russell Investments or if the security’s country of risk defined by Bloomberg is the United States and the security’s country of incorporation defined by Bloomberg is the United States.
The Fund’s portfolio manager employs a growth style of equity management, which means that the Fund seeks to invest in companies with sustainable competitive advantages versus others, long-term structural growth drivers that will lead to above-average future cash flow growth, attractive cash flow returns on invested capital, and management teams focused on creating long-term value for shareholders. The Fund’s portfolio manager also aims to invest in companies when they trade at a significant discount to the estimate of intrinsic value (i.e., companies with share prices trading significantly below what the portfolio manager believes the share price should be).
The Fund will consider selling a portfolio investment when the portfolio manager believes an unfavorable structural change occurs within a given business or the markets in which it operates, when a critical underlying investment assumption is flawed, when a more attractive reward-to-risk opportunity becomes available, when the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate.
The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in interests in real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”). The Fund is not limited in the percentage of its assets that it may invest in these instruments. The Fund may also gain investment exposure to Chinese companies through the use of a structure known as a variable interest entity (“VIE”). The VIE structure allows investors, such as the Fund, to gain exposure to sectors or industries where non-Chinese ownership is restricted or prohibited by the Chinese government. 
The Fund is “non-diversified.” As a non-diversified fund, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers, as compared with other mutual funds that are diversified.
Risk [Heading] rr_RiskHeading Principal Investment Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The bar chart and table shown below provide some 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 and life-of-fund periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund.  Performance for Class C shares includes the automatic conversion to Class A shares after eight years, where applicable. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478. 
The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return. To the extent that a class of shares was subject to the waiver or reimbursement of certain expenses during a period, had such expenses not been waived or reimbursed during the period, total returns would have been lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table shown below provide some 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 and life-of-fund periods compare to those of a broad-based securities market index that reflects the performance of the overall market applicable to the Fund.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress im.natixis.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
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.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher . The Return After Taxes on Distributions and Sale of Fund Shares for the Life of Fund period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return:
First Quarter 2023, 14.01%

Lowest Quarterly Return:
Second Quarter 2022, -13.00%
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. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes. The Return After Taxes on Distributions and Sale of Fund Shares for the Life of Fund period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Risk Nondiversified Status [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund’s net asset value.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Risk Lose Money [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Risk Not Insured Depository Institution [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock Fund shares are not bank deposits and are not guaranteed, endorsed or insured by the Federal Deposit Insurance Corporation or any other government agency, and are subject to investment risks, including possible loss of the principal invested.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, 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. The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearinghouses, such as the performance guarantee given by a central clearinghouse, are not available in connection with OTC derivatives transactions, such as foreign currency transactions. For centrally cleared derivatives, such as cleared swaps, futures and many options, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearinghouse itself.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk: 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk: 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. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. 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 equity 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. Derivatives, and particularly over-the-counter (“OTC”) derivatives, are generally subject to liquidity risk as well. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including foreign currency forwards, foreign currency futures and options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives involves other risks, such as credit/counterparty risk relating to the other party to a derivative contract (which is greater for forward currency contracts, uncleared swaps and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than any amounts paid or margin transferred to initiate derivatives positions. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Emerging Markets Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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.
The Loomis Sayles International Growth Fund’s exposure to VIEs may pose additional risks because, instead of directly investing in the underlying Chinese operating company, the Fund’s investment is in a holding company domiciled outside of China. The holding company has contractual arrangements with the operating company that are expected to provide investors, such as the Fund, with economic exposure to the operating company. However, the VIE structure is not formally recognized under Chinese law. The Chinese government may cease to tolerate VIE structures at any time or impose new restrictions. Similarly, these investments may face delisting or other adverse actions under U.S. or other non-Chinese law. Any of these events may reduce the value of the Fund’s investments in these companies or render them valueless.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Foreign Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund’s investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Large Investor Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Large Investor Risk: Ownership of shares of the Fund 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk: Leverage 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. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk: A strategy used by the Fund’s portfolio manager may fail to produce the intended result. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Equity Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Equity Securities Risk: 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. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. 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. Securities of real estate-related companies and REITs in which the Fund may invest may be considered equity securities, thus subjecting the Fund to the risks of investing in equity securities generally.  
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Currency Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may be subject to currency risk because it may invest in foreign currency forwards and foreign currency futures and may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | REITs Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Small- and Mid-Capitalization Companies Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Small- and Mid-Capitalization Companies Risk: Compared to large-capitalization companies, small- and mid-capitalization companies are more likely to have limited product lines, markets or financial resources. Stocks of these companies often trade less frequently and in limited volume and their prices may fluctuate more than stocks of large-capitalization companies. As a result, it may be relatively more difficult for the Fund to buy and sell securities of small- and mid-capitalization companies.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | MSCI All Country World ex USA Index (Net)  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 15.62%
Since Inception rr_AverageAnnualReturnSinceInception 2.31%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [8]
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.87%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.87%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.67% [9],[10]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.20%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 690
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 1,068
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,469
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,588
Past 1 Year rr_AverageAnnualReturnYear01 13.60%
Since Inception rr_AverageAnnualReturnSinceInception (3.08%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.78%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 2.53%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.58% [9],[10]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 298
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 732
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,293
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,660
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 198
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 732
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,293
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,660
Past 1 Year rr_AverageAnnualReturnYear01 18.56%
Since Inception rr_AverageAnnualReturnSinceInception (1.93%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.72%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.47%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.57% [9],[10]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.90%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 92
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 409
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 749
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,709
Past 1 Year rr_AverageAnnualReturnYear01 20.99%
Since Inception rr_AverageAnnualReturnSinceInception (0.85%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.75%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.87%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.62%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.67% [9],[10]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.95%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 97
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 446
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 818
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,865
Annual Return 2021 rr_AnnualReturn2021 (3.81%)
Annual Return 2022 rr_AnnualReturn2022 (17.50%)
Annual Return 2023 rr_AnnualReturn2023 20.81%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.01%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2023
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.00%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Past 1 Year rr_AverageAnnualReturnYear01 20.81%
Since Inception rr_AverageAnnualReturnSinceInception (0.93%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 20.78%
Since Inception rr_AverageAnnualReturnSinceInception (1.11%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles International Growth Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 12.57%
Since Inception rr_AverageAnnualReturnSinceInception (0.66%)
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks high total investment return through a combination of current income and capital appreciation.
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. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 70 of the Prospectus, in Appendix A to the Prospectus and on page 130 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees(fees paid directly from your investment)
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)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination April 30, 2025
Expenses Deferred Charges [Text Block] rr_ExpensesDeferredChargesTextBlock A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Other expenses for Class T shares are estimated for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading  Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. 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:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If shares are not redeemed:
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 25% of the average value of its portfolio. 
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 25.00%
Strategy [Heading] rr_StrategyHeading Investments, Risks and PerformancePrincipal Investment Strategies
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investment grade fixed-income securities (for example, bonds and other investments that the Adviser believes have similar economic characteristics, such as notes, debentures and loans). “Investment grade” securities are those securities that are rated in one of the top four categories at the time of purchase by at least one of the three major rating agencies — Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investor Services, Inc. (“Fitch”) or S&P Global Ratings (“S&P”) or, if unrated, are determined by the Adviser to be of comparable quality. Although the Fund invests primarily in investment grade fixed-income securities, it may invest up to 15% of its assets in below investment grade fixed-income securities (also known as “junk bonds”). There is no minimum rating for the securities in which the Fund may invest. The Fund may invest in fixed-income securities of any maturity.
In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.
Three themes typically drive the Fund’s investment approach. First, the Adviser generally seeks fixed-income securities of issuers whose credit profiles it believes are improving. Second, the Fund may invest significantly in securities the prices of which the Adviser believes are more sensitive to events related to the underlying issuer than to changes in general interest rates or overall market default rates. The Adviser believes that the Fund may generate positive returns by having a portion of the Fund’s assets invested in non-market-related securities, rather than by relying primarily on changes in interest rates to produce returns for the Fund. Third, the Adviser analyzes different sectors of the economy and differences in the yields (“spreads”) of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk. The Adviser generally prefers securities that are protected against calls (early redemption by the issuer).
In connection with its principal investment strategies, the Fund may invest up to 30% of its assets in U.S. dollar-denominated foreign securities, including emerging markets securities. The Fund may also invest in U.S. dollar-denominated obligations of supranational entities without limit (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 corporate securities, U.S. government securities, commercial paper, zero-coupon securities, collateralized loan obligations, mortgage-backed securities, including mortgage dollar rolls, stripped mortgage-backed securities and collateralized mortgage obligations and other asset-backed securities, when-issued securities, convertible 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, and structured notes. The Fund may also invest in futures, forward contracts and swaps (including credit default swaps) for hedging and investment purposes. Except as provided above or as required by applicable law, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading] rr_RiskHeading Principal Investment Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The bar chart and table shown below provide some 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.  Performance for Class C shares includes the automatic conversion to Class A shares after eight years, where applicable. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478. 
The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return. To the extent that a class of shares was subject to the waiver or reimbursement of certain expenses during a period, had such expenses not been waived or reimbursed during the period, total returns would have been lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table shown below provide some 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.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress im.natixis.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T 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.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return:
Second Quarter 2020, 8.60%
Lowest Quarterly Return:
Second Quarter 2022, -5.35%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns(for the periods ended December 31, 2023)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund’s other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.
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. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Risk Lose Money [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Risk Not Insured Depository Institution [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock Fund shares are not bank deposits and are not guaranteed, endorsed or insured by the Federal Deposit Insurance Corporation or any other government agency, and are subject to investment risks, including possible loss of the principal invested.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Below Investment Grade Fixed-Income Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Below Investment Grade Fixed-Income Securities Risk: The Fund’s investments in below investment grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, 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. The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearing houses, such as the performance guarantee given by a central clearing house, are not available in connection with over-the-counter (“OTC”) derivatives transactions, such as foreign currency transactions. For centrally cleared derivatives, such as cleared swaps, futures and many options, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearing house itself. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk: 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Interest Rate Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk: 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 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk: 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. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. 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 equity 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. Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including forward currency contracts, structured notes and swap transactions (including credit default swaps)) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives, such as forward currency contracts, structured notes and swap transactions (including credit default swaps), involves other risks, such as credit/counterparty risk relating to the other party to a derivative contract (which is greater for forward currency contracts, uncleared swaps, and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than any amounts paid or margin transferred to initiate derivatives positions. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Emerging Markets Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Foreign Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk: Leverage 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. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity, inflation and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, 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 also may incur a loss when there is a prepayment of securities that were purchased at a premium. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.53% [11]
Past 5 Years rr_AverageAnnualReturnYear05 1.10% [11]
Past 10 Years rr_AverageAnnualReturnYear10 1.81% [11]
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Bloomberg U.S. Government/Credit Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.72%
Past 5 Years rr_AverageAnnualReturnYear05 1.41%
Past 10 Years rr_AverageAnnualReturnYear10 1.97%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.25%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [12]
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.81%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 497
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 666
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 849
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,378
Past 1 Year rr_AverageAnnualReturnYear01 2.75%
Past 5 Years rr_AverageAnnualReturnYear05 1.95%
Past 10 Years rr_AverageAnnualReturnYear10 2.05%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.56%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.49%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 252
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 486
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 843
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,649
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 152
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 486
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 843
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,649
Past 1 Year rr_AverageAnnualReturnYear01 5.43%
Past 5 Years rr_AverageAnnualReturnYear05 2.06%
Past 10 Years rr_AverageAnnualReturnYear10 1.88%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.07%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.47%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.03% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.44%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 45
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 148
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 260
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 589
Past 1 Year rr_AverageAnnualReturnYear01 7.55%
Past 5 Years rr_AverageAnnualReturnYear05 3.15%
Past 10 Years rr_AverageAnnualReturnYear10 2.83%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16% [14]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.81%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.74%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 324
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 495
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 682
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,220
Past 1 Year rr_AverageAnnualReturnYear01 4.62%
Past 5 Years rr_AverageAnnualReturnYear05 2.32%
Past 10 Years rr_AverageAnnualReturnYear10 2.24%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.16%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.56%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.49%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 50
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 172
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 306
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 695
Annual Return 2014 rr_AnnualReturn2014 5.14%
Annual Return 2015 rr_AnnualReturn2015 (5.08%)
Annual Return 2016 rr_AnnualReturn2016 6.16%
Annual Return 2017 rr_AnnualReturn2017 6.66%
Annual Return 2018 rr_AnnualReturn2018 (0.32%)
Annual Return 2019 rr_AnnualReturn2019 9.04%
Annual Return 2020 rr_AnnualReturn2020 11.68%
Annual Return 2021 rr_AnnualReturn2021 0.24%
Annual Return 2022 rr_AnnualReturn2022 (11.31%)
Annual Return 2023 rr_AnnualReturn2023 7.50%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 8.60%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (5.35%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Past 1 Year rr_AverageAnnualReturnYear01 7.50%
Past 5 Years rr_AverageAnnualReturnYear05 3.08%
Past 10 Years rr_AverageAnnualReturnYear10 2.74%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.61%
Past 5 Years rr_AverageAnnualReturnYear05 1.28%
Past 10 Years rr_AverageAnnualReturnYear10 1.06%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 4.39%
Past 5 Years rr_AverageAnnualReturnYear05 1.70%
Past 10 Years rr_AverageAnnualReturnYear10 1.48%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Investment Grade Bond Fund) | Admin Class  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.40%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.41% [15]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.06%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [13]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.99%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 101
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 330
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 578
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,288
Past 1 Year rr_AverageAnnualReturnYear01 6.99%
Past 5 Years rr_AverageAnnualReturnYear05 2.56%
Past 10 Years rr_AverageAnnualReturnYear10 2.25%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The Fund seeks high current income with a secondary objective of capital growth.
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. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 70 of the Prospectus, in Appendix A to the Prospectus and on page 130 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Expense Breakpoint Discounts [Text] rr_ExpenseBreakpointDiscounts You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Funds Complex.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 100,000
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees(fees paid directly from your investment)
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)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination April 30, 2025
Other Expenses, New Fund, Based on Estimates [Text] rr_OtherExpensesNewFundBasedOnEstimates Other expenses for Class T shares are estimated for the current fiscal year.
Expense Example [Heading] rr_ExpenseExampleHeading Example
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. The example for Class C shares for the ten-year period reflects the conversion to Class A shares after eight years. 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:
Expense Example by, Year, Caption [Text] rr_ExpenseExampleByYearCaption If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text] rr_ExpenseExampleNoRedemptionByYearCaption If shares are not redeemed:
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 39% of the average value of its portfolio. 
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 39.00%
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 in income producing securities (including below investment grade securities, or “junk bonds”) with a focus on U.S. corporate bonds, convertible securities, foreign debt instruments, including those in emerging markets and related foreign currency transactions, and U.S. government securities. Below investment grade fixed-income securities are rated below investment grade quality (i.e., none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or S&P Global Ratings (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. The Fund may invest up to 35% of its assets in preferred stocks and dividend-paying common stocks. The portfolio managers may shift the Fund’s assets among various types of income-producing securities based upon changing market conditions. The Adviser performs its own extensive credit analyses to determine the creditworthiness and potential for capital appreciation of a security.
The Fund’s portfolio managers use a flexible approach to identify securities in the global marketplace with characteristics including discounted price compared to economic value, undervalued credit ratings with strong or improving credit profiles and yield premium relative to its benchmark (although not all of the securities selected will have these attributes).
In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.
In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser seeks to buy bonds that offer a positive yield advantage over the market and, in its view, have room to increase in price. It may also invest to take advantage of what the portfolio managers believe are temporary disparities in the yield of different segments of the market for U.S. government securities. The Adviser provides the portfolio managers with maximum flexibility to find investment opportunities in a wide range of markets, both domestic and foreign. This flexible approach provides the Fund with access to a wide array of investment opportunities. The three key sectors that the portfolio managers focus upon are U.S. corporate issues (including convertible securities), foreign debt securities and U.S. government securities. The Fund’s portfolio managers maintain a core of the Fund’s investments in corporate bond issues and shift its assets among other income-producing securities as opportunities develop. The Fund generally seeks to maintain a high level of diversification as a form of risk management.
In connection with its principal investment strategies, the Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”), other privately placed investments such as private credit investments, structured notes, collateralized loan obligations, zero-coupon bonds, pay-in-kind bonds, mortgage-related securities, stripped securities and futures, swaps (including credit default swaps) and foreign currency transactions (such as forward currency contracts) for hedging and investment purposes. Except as provided above or as required by applicable law, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading] rr_RiskHeading Principal Investment Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Risk/Return Bar Chart and Table
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The bar chart and table shown below provide some 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.  Performance for Class C shares includes the automatic conversion to Class A shares after eight years, where applicable. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at im.natixis.com and/or by calling the Fund toll-free at 800-225-5478. 
The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return. To the extent that a class of shares was subject to the waiver or reimbursement of certain expenses during a period, had such expenses not been waived or reimbursed during the period, total returns would have been lower.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table shown below provide some 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.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress im.natixis.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T 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.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
Highest Quarterly Return: Fourth Quarter 2023, 7.70%

Lowest Quarterly Return: First Quarter 2020, -12.29%
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns(for the periods ended December 31, 2023)
Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock
The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund’s other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.
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. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Risk Lose Money [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock You may lose money by investing in the Fund.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Risk Not Insured Depository Institution [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock Fund shares are not bank deposits and are not guaranteed, endorsed or insured by the Federal Deposit Insurance Corporation or any other government agency, and are subject to investment risks, including possible loss of the principal invested.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Below Investment Grade Fixed-Income Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Below Investment Grade Fixed-Income Securities Risk: The Fund’s investments in below investment grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Credit/Counterparty Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, 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. The Fund will be subject to credit/counterparty risk with respect to the counterparties to its derivatives transactions. This risk will be heightened to the extent the Fund enters into derivative transactions with a single counterparty (or affiliated counterparties that are part of the same organization), causing the Fund to have significant exposure to such counterparty. Many of the protections afforded to participants on organized exchanges and clearinghouses, such as the performance guarantee given by a central clearinghouse, are not available in connection with over-the-counter (“OTC”) derivatives transactions, such as foreign currency transactions. For centrally cleared derivatives, such as cleared swaps, futures and many options, the primary credit/counterparty risk is the creditworthiness of the Fund’s clearing broker and the central clearinghouse itself.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Market/Issuer Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Market/Issuer Risk: 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Interest Rate Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Interest Rate Risk: 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 bonds may be 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Liquidity Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Liquidity Risk: 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. Decreases in the number of financial institutions willing to make markets in the Fund’s investments or in their capacity or willingness to transact may increase the Fund’s exposure to this risk. 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 equity 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. Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Cybersecurity and Technology Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Cybersecurity and Technology Risk: The Fund, its service providers, and other market participants increasingly depend on complex information technology and communications systems, which 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Derivatives Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures, structured notes, swaps (including credit default swaps) and forward currency contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund’s use of derivatives, such as futures, structured notes, swaps (including credit default swaps) and forward currency contracts involves other risks, such as credit/counterparty risk relating to the other party to a derivative contract (which is greater for forward currency contracts, uncleared swaps and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than any amounts paid or margin transferred to initiate derivatives positions. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Emerging Markets Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Emerging Markets Risk: In addition to the risks of investing in foreign investments generally, 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Foreign Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund’s investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Leverage Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Leverage Risk: Leverage 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. 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Management Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity, inflation and valuation risk), mortgage-related and asset-backed securities are subject to the risks of the mortgages and assets underlying the securities as well as prepayment risk, 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 also may incur a loss when there is a prepayment of securities that were purchased at a premium. 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.
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Equity Securities Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Equity Securities Risk: 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 II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Currency Risk [Member]  
Prospectus: rr_ProspectusTable  
Risk [Text Block] rr_RiskTextBlock
Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may be subject to currency risk because it may invest in currency-related instruments and may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. 
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Bloomberg U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.53%
Past 5 Years rr_AverageAnnualReturnYear05 1.10%
Past 10 Years rr_AverageAnnualReturnYear10 1.81%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.25%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none [16]
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.00%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.93%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 516
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 723
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 947
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,591
Past 1 Year rr_AverageAnnualReturnYear01 3.40%
Past 5 Years rr_AverageAnnualReturnYear05 0.98%
Past 10 Years rr_AverageAnnualReturnYear10 1.44%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.75%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.68%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 271
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 544
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 942
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 1,858
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 171
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 544
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 942
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,858
Past 1 Year rr_AverageAnnualReturnYear01 6.26%
Past 5 Years rr_AverageAnnualReturnYear05 1.10%
Past 10 Years rr_AverageAnnualReturnYear10 1.27%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.08%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.66%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.03% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.63%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 64
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 208
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 365
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 820
Past 1 Year rr_AverageAnnualReturnYear01 8.45%
Past 5 Years rr_AverageAnnualReturnYear05 2.19%
Past 10 Years rr_AverageAnnualReturnYear10 2.22%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17% [18]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.00%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.93%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 343
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 554
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 782
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,438
Past 1 Year rr_AverageAnnualReturnYear01 5.31%
Past 5 Years rr_AverageAnnualReturnYear05 1.34%
Past 10 Years rr_AverageAnnualReturnYear10 1.62%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.17%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.75%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.68%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 69
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 233
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 410
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 924
Annual Return 2014 rr_AnnualReturn2014 5.86%
Annual Return 2015 rr_AnnualReturn2015 (7.42%)
Annual Return 2016 rr_AnnualReturn2016 8.56%
Annual Return 2017 rr_AnnualReturn2017 7.50%
Annual Return 2018 rr_AnnualReturn2018 (2.69%)
Annual Return 2019 rr_AnnualReturn2019 11.05%
Annual Return 2020 rr_AnnualReturn2020 1.40%
Annual Return 2021 rr_AnnualReturn2021 4.12%
Annual Return 2022 rr_AnnualReturn2022 (12.60%)
Annual Return 2023 rr_AnnualReturn2023 8.30%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return:
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 7.70%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2023
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return:
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.29%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Past 1 Year rr_AverageAnnualReturnYear01 8.30%
Past 5 Years rr_AverageAnnualReturnYear05 2.11%
Past 10 Years rr_AverageAnnualReturnYear10 2.13%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 5.83%
Past 5 Years rr_AverageAnnualReturnYear05 0.28%
Past 10 Years rr_AverageAnnualReturnYear10 0.21%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 4.88%
Past 5 Years rr_AverageAnnualReturnYear05 0.89%
Past 10 Years rr_AverageAnnualReturnYear10 0.94%
(Loomis Sayles Funds II - Classes A, C, N, T, Y, and Admin) | (Loomis Sayles Strategic Income Fund) | Admin Class  
Prospectus: rr_ProspectusTable  
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage) rr_MaximumDeferredSalesChargeOverOther none
Redemption Fee rr_RedemptionFee none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 0.58%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.42% [19]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.25%
Fee Waiver or Reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.07% [17]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.18%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 390
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 680
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,505
Past 1 Year rr_AverageAnnualReturnYear01 7.78%
Past 5 Years rr_AverageAnnualReturnYear05 1.60%
Past 10 Years rr_AverageAnnualReturnYear10 1.63%
[1]
1 Effective May 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.
[2]
* A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
[3]
1 The Fund’s operating expenses have been restated to reflect a reduction in management fees, effective as of July 1, 2023, as if reduction had been in effect during the fiscal year ended December 31, 2023. The information has been restated to better reflect anticipated expenses of the Fund.
[4]
2 Other expenses include acquired fund fees and expenses of less than 0.01%.
[5]
4 Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.95%, 1.70%, 0.65%, 0.95% and 0.70% of the Fund’s average daily net assets for Class A, C, N, T and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below both (1) the class’ applicable expense limitation at the time such amounts were waived/reimbursed and (2) the class’ current applicable expense limitation. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.
[6]
5 Natixis Advisors, LLC (“Natixis Advisors”) has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees.
[7]
3 Other expenses for Class T shares are estimated for the current fiscal year.
[8]
* A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
[9]
1 Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 1.20%, 1.95%, 0.90% and 0.95% of the Fund’s average daily net assets for Class A, C, N and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below both (1) the class’ applicable expense limitation at the time such amounts were waived/reimbursed and (2) the class’ current applicable expense limitation. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.
[10]
2 Natixis Advisors, LLC (“Natixis Advisors”) has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees.
[11]
1 Effective May 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. For reference, the performance of the Fund’s former primary index is included in the table above.
[12]
* A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
[13]
3 Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.74%, 1.49%, 0.44%, 0.74%, 0.49% and 0.99% of the Fund’s average daily net assets for Class A, C, N, T, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below both (1) the class’ applicable expense limitation at the time such amounts were waived/reimbursed and (2) the class’ current applicable expense limitation. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.
[14]
1 Other expenses for Class T shares are estimated for the current fiscal year.
[15]
2 Other expenses include an administrative services fee of 0.25% for Admin Class shares.
[16]
* A 1.00% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $1,000,000 or more that are redeemed within eighteen months of the date of purchase.
[17]
3 Loomis, Sayles & Company, L.P. (“Loomis Sayles” or the “Adviser”) has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.93%, 1.68%, 0.63%, 0.93%, 0.68% and 1.18% of the Fund’s average daily net assets for Class A, C, N, T, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through April 30, 2025 and may be terminated before then only with the consent of the Fund’s Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below both (1) the class’ applicable expense limitation at the time such amounts were waived/reimbursed and (2) the class’ current applicable expense limitation. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.
[18]
1 Other expenses for Class T shares are estimated for the current fiscal year.
[19]
2 Other expenses include an administrative services fee of 0.25% for Admin Class shares.