Objective, Primary [Text Block]

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

rr_ObjectivePrimaryTextBlock

The Fund’s investment goal is high total investment return through a combination of capital appreciation and current income.

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 48 of the Prospectus, in Appendix A to the Prospectus and on page 111 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

January 31, 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. 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 19% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

19.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and PerformancePrincipal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in equity and fixed-income securities of U.S. and foreign issuers. Equity securities purchased by the Fund may include common stocks, preferred stocks, depositary receipts, warrants, securities convertible into common or preferred stocks, interests in real estate investment trusts (“REITs”) and/or real estate-related securities and other equity-like interests in an issuer. The Fund generally invests in equity securities of issuers with a minimum market capitalization of $1 billion at the time of investment. Fixed-income securities purchased by the Fund may include bonds and other debt obligation of U.S. and foreign issuers, including but not limited to corporations, governments and supranational entities. The Fund may invest in fixed-income securities regardless of market capitalization, maturity or duration parameters. The Fund will invest a significant portion of its assets outside the U.S., including securities of issuers located in emerging market countries. There are various ways the Adviser determines how an investment is economically tied to a country or region. Typically, the Adviser will look at either the countries of risk or countries of issuance and report based on either method.

The portfolio managers reallocate the Fund’s assets between equity and fixed income securities based on their assessment of current market conditions, the attractiveness of individual securities and the relative opportunities within each asset class, among other factors. In deciding which equity securities to buy and sell, the Adviser generally looks to purchase quality companies at attractive valuations with the potential to grow intrinsic value over time. The Adviser uses discounted cash flow analysis, among other methods of analysis, to determine a company’s intrinsic value. In deciding which fixed-income securities to buy and sell, the Adviser generally looks for securities that it believes are undervalued and have the potential for credit upgrades, which may include securities that are below investment grade (also known as “junk bonds”).

In assessing both risks and opportunities related to the Fund’s investments, the Adviser seeks to take into account the factors that may influence an investment’s performance over time. This includes material environmental, social, and governance (“ESG”) risks and opportunities (those which could cause a material impact on the value of an investment).

In integrating risks and opportunities into its investment process, the Adviser takes into account ESG factors that it deems may be material to an investment, such as carbon intensity, renewable energy usage from low carbon sources, workplace diversity, and board composition, at all stages of the investment management process, including strategy development, investment analysis and due diligence, and portfolio construction (including at the point where the investment team considers investment opportunities), and as part of its ongoing monitoring and risk analysis.

To the extent that the Adviser concludes that there is an ESG risk associated with an investment, the Adviser assesses the probability and potential impact of that ESG risk against the potential pecuniary advantage to the Fund of making the investment. If the Adviser believes the potential pecuniary advantage outweighs the actual or potential impact of the ESG risk, then the Adviser may still make the investment.

The Fund may also invest in foreign currencies, collateralized mortgage obligations, collateralized loan obligations, zero-coupon securities, when-issued securities, REITs, securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”), other privately placed investments such as private equity investments, mortgage-related securities, convertible securities and structured notes. The Fund may also engage in active and frequent trading of securities and engage in options or foreign currency transactions (such as forward currency contracts) for hedging and investment purposes and futures transactions and swap transactions (including credit default swaps). Frequent trading may produce high transaction costs and a high level of taxable capital gains, including short-term capital gains taxable as ordinary income, which may lower the Fund’s return. The Adviser may hedge currency risk for the Fund (including “cross hedging” between two or more foreign currencies) if it believes the outlook for a particular foreign currency is unfavorable. 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 two broad measures of market performance. The Blended Index is an unmanaged, blended index composed of the following weights: 60% MSCI All Country World Index (Net) and 40% Bloomberg Global Aggregate Bond Index. The two indices composing the Blended Index measure, respectively, the performance of global equity securities and global investment grade fixed income securities. Performance for Class C shares includes the automatic conversion to Class A shares after eight years. 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

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Fund did not have Class T shares outstanding during the periods shown above.

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.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Highest Quarterly Return:

Second Quarter 2020, 16.50%

Lowest Quarterly Return:

Second Quarter 2022, -15.95%

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.

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 | (Loomis Sayles Global Allocation Fund) | Equity Securities Risk [Member]

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Below Investment Grade Fixed-Income Securities Risk [Member]

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. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Foreign Securities Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Credit/Counterparty Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Market/Issuer Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Allocation Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Currency Risk [Member]

rr_RiskTextBlock

Allocation Risk: The Fund’s investment performance depends, in part, on how its assets are allocated. The allocation between asset classes and market exposures may not be optimal in every market condition. You could lose money on your investment in the Fund as a result of this allocation.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Cybersecurity and Technology Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Derivatives Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | ESG Risk [Member]

rr_RiskTextBlock

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including options, forward currency contracts, futures transactions, 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 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Emerging Markets Risk [Member]

rr_RiskTextBlock

ESG Risk: Risks related to ESG factors may impact the performance of securities in which the Fund invests. Such ESG factors include, for example, climate change; resource depletion; renewal energy usage; governance, diversity and labor practices; workplace health and safety; supply chain standards; and product health and safety. The companies or issuers in which the Fund invests may not have favorable ESG characteristics.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Inflation/Deflation Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Interest Rate Risk [Member]

rr_RiskTextBlock

Inflation/Deflation Risk: Inflation risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. As inflation increases, the real value of the Fund’s portfolio could decline. Inflation rates may change frequently and drastically. The Fund’s investments may not keep pace with inflation, which may result in losses to the Fund’s investors. Recently, inflation rates in the United States and elsewhere have been increasing. There can be no assurance that this trend will not continue or that efforts to slow or reverse inflation will not harm the economy and asset values. Deflation risk is the risk that prices throughout the economy decline over time - the opposite of inflation. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund’s portfolio.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Large Investor Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Leverage Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Liquidity Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Management Risk [Member]

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 credit and other investments, are generally subject to significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. In other circumstances, liquid investments may become illiquid. 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Mortgage-Related Securities Risk [Member]

rr_RiskTextBlock

Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | REITs Risk [Member]

rr_RiskTextBlock

Mortgage-Related 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 securities are subject to the risks of the mortgages 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 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | MSCI All Country World Index (Net)

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.

rr_ProspectusTable

rr_AverageAnnualReturnYear01

22.20%

rr_AverageAnnualReturnYear05

11.72%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Blended Index (60% MSCI All Country World Index (Net) / 40% Bloomberg Global Aggregate Bond Index)

rr_AverageAnnualReturnYear10

7.93%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

15.43%

rr_AverageAnnualReturnYear05

7.01%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class A

rr_AverageAnnualReturnYear10

5.05%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

^[1]

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.74%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.18%

rr_ExpensesOverAssets

1.17%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[2]

rr_NetExpensesOverAssets

1.17%

rr_ExpenseExampleYear01

$ 687

rr_ExpenseExampleYear03

925

rr_ExpenseExampleYear05

1,182

rr_ExpenseExampleYear10

$ 1,914

rr_AverageAnnualReturnYear01

15.15%

rr_AverageAnnualReturnYear05

7.97%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class C

rr_AverageAnnualReturnYear10

6.36%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

1.00%

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.74%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.18%

rr_ExpensesOverAssets

1.92%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[2]

rr_NetExpensesOverAssets

1.92%

rr_ExpenseExampleYear01

$ 295

rr_ExpenseExampleYear03

603

rr_ExpenseExampleYear05

1,037

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleYear10

2,048

rr_ExpenseExampleNoRedemptionYear01

195

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

603

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,037

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,048

rr_AverageAnnualReturnYear01

20.19%

rr_AverageAnnualReturnYear05

8.43%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class N

rr_AverageAnnualReturnYear10

6.35%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.74%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.08%

rr_ExpensesOverAssets

0.82%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[2]

rr_NetExpensesOverAssets

0.82%

rr_ExpenseExampleYear01

$ 84

rr_ExpenseExampleYear03

262

rr_ExpenseExampleYear05

455

rr_ExpenseExampleYear10

$ 1,014

rr_AverageAnnualReturnYear01

22.58%

rr_AverageAnnualReturnYear05

9.63%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class N | MSCI All Country World Index (Net)

rr_AverageAnnualReturnSinceInception

8.72%

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class N | Blended Index (60% MSCI All Country World Index (Net) / 40% Bloomberg Global Aggregate Bond Index)

rr_AverageAnnualReturnSinceInception

9.71%

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class T

rr_AverageAnnualReturnSinceInception

6.17%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.50%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.74%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.18%

^[3]

rr_ExpensesOverAssets

1.17%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[2]

rr_NetExpensesOverAssets

1.17%

rr_ExpenseExampleYear01

$ 366

rr_ExpenseExampleYear03

612

rr_ExpenseExampleYear05

878

rr_ExpenseExampleYear10

$ 1,635

rr_AverageAnnualReturnYear01

19.14%

rr_AverageAnnualReturnYear05

8.71%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class Y

rr_AverageAnnualReturnYear10

6.72%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.74%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.18%

rr_ExpensesOverAssets

0.92%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[2]

rr_NetExpensesOverAssets

0.92%

rr_ExpenseExampleYear01

$ 94

rr_ExpenseExampleYear03

293

rr_ExpenseExampleYear05

509

Highest Quarterly Return, Label

rr_ExpenseExampleYear10

$ 1,131

Annual Return 2014

rr_AnnualReturn2014

3.53%

Annual Return 2015

rr_AnnualReturn2015

1.69%

Annual Return 2016

rr_AnnualReturn2016

4.67%

Annual Return 2017

rr_AnnualReturn2017

22.11%

Annual Return 2018

rr_AnnualReturn2018

(5.04%)

Annual Return 2019

rr_AnnualReturn2019

26.80%

Annual Return 2020

rr_AnnualReturn2020

15.38%

Annual Return 2021

rr_AnnualReturn2021

14.38%

Annual Return 2022

rr_AnnualReturn2022

(23.05%)

Annual Return 2023

rr_AnnualReturn2023

22.43%

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return:

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

16.50%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return:

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.95%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2022

rr_AverageAnnualReturnYear01

22.43%

rr_AverageAnnualReturnYear05

9.53%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class Y | Return After Taxes on Distributions

rr_AverageAnnualReturnYear10

7.26%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

21.30%

rr_AverageAnnualReturnYear05

8.01%

Loomis Sayles Funds II | (Loomis Sayles Global Allocation Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnYear10

5.96%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

14.07%

rr_AverageAnnualReturnYear05

7.45%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund)

rr_AverageAnnualReturnYear10

5.62%

Objective, Primary [Text Block]

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

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

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

January 31, 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

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

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

13.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and PerformancePrincipal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks, convertible securities and warrants. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

The Fund normally invests across a wide range of sectors and industries. 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, 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 invest up to 20% of its assets in foreign securities, including depositary receipts and emerging market securities. Although certain equity 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 they are 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. The Fund may also invest in affiliated and unaffiliated mutual funds and exchange-traded funds, to the extent permitted by the Investment Company Act of 1940. 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”). 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 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. 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.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Fund did not have Class T shares outstanding during the periods shown above.

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

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 Returns:

Second Quarter 2020, 23.88%

Lowest Quarterly Return:

Second Quarter 2022, -22.80%

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.

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Equity Securities Risk [Member]

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Foreign Securities Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Credit/Counterparty Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Market/Issuer Risk [Member]

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 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Currency Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Cybersecurity and Technology Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Derivatives Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Emerging Markets Risk [Member]

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 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Leverage Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Liquidity Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Management Risk [Member]

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, 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. Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. 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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | REITs Risk [Member]

rr_RiskTextBlock

Management Risk: A strategy used by the Fund’s portfolio manager may fail to produce the intended result.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Small- and Mid-Capitalization Companies Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Investments in Other Investment Companies Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | S&P 500® Index

rr_RiskTextBlock

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including exchange-traded funds, in which it invests in addition to its own expenses.

rr_ProspectusTable

rr_AverageAnnualReturnYear01

26.29%

^[4]

rr_AverageAnnualReturnYear05

15.69%

^[4]

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Russell 1000® Growth Index

rr_AverageAnnualReturnYear10

12.03%

^[4]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

42.68%

rr_AverageAnnualReturnYear05

19.50%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class A

rr_AverageAnnualReturnYear10

14.86%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

5.75%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

^[5]

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.50%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.17%

rr_ExpensesOverAssets

0.92%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[6]

rr_NetExpensesOverAssets

0.92%

rr_ExpenseExampleYear01

$ 663

rr_ExpenseExampleYear03

851

rr_ExpenseExampleYear05

1,055

rr_ExpenseExampleYear10

$ 1,641

rr_AverageAnnualReturnYear01

42.36%

rr_AverageAnnualReturnYear05

16.00%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class C

rr_AverageAnnualReturnYear10

13.27%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

1.00%

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.50%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.17%

rr_ExpensesOverAssets

1.67%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[6]

rr_NetExpensesOverAssets

1.67%

rr_ExpenseExampleYear01

$ 270

rr_ExpenseExampleYear03

526

rr_ExpenseExampleYear05

907

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleYear10

1,777

rr_ExpenseExampleNoRedemptionYear01

170

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

526

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

907

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,777

rr_AverageAnnualReturnYear01

48.85%

rr_AverageAnnualReturnYear05

16.50%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class N

rr_AverageAnnualReturnYear10

13.26%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.50%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.08%

rr_ExpensesOverAssets

0.58%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[6]

rr_NetExpensesOverAssets

0.58%

rr_ExpenseExampleYear01

$ 59

rr_ExpenseExampleYear03

186

rr_ExpenseExampleYear05

324

rr_ExpenseExampleYear10

$ 726

rr_AverageAnnualReturnYear01

51.61%

rr_AverageAnnualReturnYear05

17.78%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class T

rr_AverageAnnualReturnYear10

14.31%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.50%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.50%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.17%

^[7]

rr_ExpensesOverAssets

0.92%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[6]

rr_NetExpensesOverAssets

0.92%

rr_ExpenseExampleYear01

$ 342

rr_ExpenseExampleYear03

536

rr_ExpenseExampleYear05

747

rr_ExpenseExampleYear10

$ 1,353

rr_AverageAnnualReturnYear01

47.24%

rr_AverageAnnualReturnYear05

16.80%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class Y

rr_AverageAnnualReturnYear10

13.66%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.50%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.17%

rr_ExpensesOverAssets

0.67%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[6]

rr_NetExpensesOverAssets

0.67%

rr_ExpenseExampleYear01

$ 68

rr_ExpenseExampleYear03

214

rr_ExpenseExampleYear05

373

Highest Quarterly Return, Label

rr_ExpenseExampleYear10

$ 835

Annual Return 2014

rr_AnnualReturn2014

11.27%

Annual Return 2015

rr_AnnualReturn2015

10.02%

Annual Return 2016

rr_AnnualReturn2016

5.87%

Annual Return 2017

rr_AnnualReturn2017

32.64%

Annual Return 2018

rr_AnnualReturn2018

(2.48%)

Annual Return 2019

rr_AnnualReturn2019

31.72%

Annual Return 2020

rr_AnnualReturn2020

31.77%

Annual Return 2021

rr_AnnualReturn2021

18.65%

Annual Return 2022

rr_AnnualReturn2022

(27.64%)

Annual Return 2023

rr_AnnualReturn2023

51.42%

rr_HighestQuarterlyReturnLabel

Highest Quarterly Returns:

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

23.88%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2020

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return:

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(22.80%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2022

rr_AverageAnnualReturnYear01

51.42%

rr_AverageAnnualReturnYear05

17.68%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class Y | Return After Taxes on Distributions

rr_AverageAnnualReturnYear10

14.23%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

49.34%

rr_AverageAnnualReturnYear05

15.91%

Loomis Sayles Funds II | (Loomis Sayles Growth Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnYear10

13.09%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

31.88%

rr_AverageAnnualReturnYear05

14.02%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund)

rr_AverageAnnualReturnYear10

11.72%

Objective, Primary [Text Block]

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

rr_ObjectivePrimaryTextBlock

The Fund seeks high current return consistent with preservation 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 $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 48 of the Prospectus, in Appendix A to the Prospectus and on page 111 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

January 31, 2025

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

A 0.75% contingent deferred sales charge (“CDSC”) may apply to certain purchases of Class A shares of $500,000 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 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

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

267.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and PerformancePrincipal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investments issued or guaranteed by the U.S. government, its agencies or instrumentalities.

The Adviser follows a total return-oriented investment approach in selecting securities for the Fund. It seeks securities that will provide the Fund with an average credit quality equal to the credit rating of the U.S. government’s long-term debt and an effective portfolio duration range of two to four years (although not all securities selected will have these characteristics and the Adviser may look for other characteristics if market conditions change). The Fund may invest in securities with credit quality above or below the credit rating of the U.S. government’s long-term debt. In determining credit quality, the Adviser will look to the highest credit rating assigned by S&P Global Ratings (“S&P”), Fitch Investor Services, Inc. (“Fitch”) or Moody’s Investors Service, Inc. (“Moody’s”).

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’s research analysts work closely with the Fund’s portfolio managers to develop an outlook on the economy from research produced by various financial firms and specific forecasting services or from economic data released by the U.S. and foreign governments as well as the Federal Reserve Bank. The analysts also conduct a thorough review of individual securities to identify what they consider attractive values in the U.S. government security marketplace through the use of quantitative tools such as internal and external computer systems and software. The Adviser continuously monitors an issuer’s creditworthiness to assess whether the obligation remains an appropriate investment for the Fund. The Adviser seeks to balance opportunities for yield and price performance by combining macroeconomic analysis with individual security selection. It emphasizes securities that tend to perform particularly well in response to interest rate changes, such as U.S. Treasury securities in a declining interest rate environment and mortgage-backed or U.S. government agency securities in a steady or rising interest rate environment. The Adviser seeks to increase the opportunity for higher yields while maintaining the greater price stability that intermediate-term bonds have compared to bonds with longer maturities. The Adviser also uses a systematic model based on supply and demand patterns in purchasing and selling certain treasury securities and related derivatives.

In connection with its principal investment strategies, the Fund may also invest in investment grade corporate notes and bonds, collateralized loan obligations, zero-coupon bonds, securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”), and other privately placed investments such as private credit investments, asset-backed securities and mortgage-related securities including mortgage dollar rolls, and when-issued securities, delayed delivery securities and/or forward commitment securities. 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. 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.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

Performance One Year or Less [Text]

rr_PerformanceOneYearOrLess

The Fund did not have Class T shares outstanding during the periods shown above.

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

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, 2.95%

Lowest Quarterly Return:

First Quarter 2022, -2.45%

Performance Table Heading

rr_PerformanceTableHeading

Average Annual Total Returns(for the periods ended December 31, 2023)

Performance Table Closing [Text Block]

rr_PerformanceTableClosingTextBlock

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Market/Issuer Risk [Member]

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Cybersecurity and Technology Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Interest Rate Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Liquidity Risk [Member]

rr_RiskTextBlock

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Management Risk [Member]

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. Derivatives, and particularly OTC derivatives, are generally subject to liquidity risk as well. In other circumstances, liquid investments may become illiquid. Liquidity issues may also make it difficult to value the Fund’s investments. The Fund may invest in liquid investments that become illiquid due to financial distress, or geopolitical events such as sanctions, trading halts or wars.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Mortgage-Related and Asset-Backed Securities Risk [Member]

rr_RiskTextBlock

Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | U.S. Government Securities Risk [Member]

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.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Agency Securities Risk [Member]

rr_RiskTextBlock

U.S. Government Securities Risk: Investments in certain U.S. government securities may not be supported by the full faith and credit of the U.S. government. Accordingly, no assurance can be given that the U.S. government will provide financial support to U.S. government agencies, instrumentalities or sponsored enterprises if it is not obligated to do so by law. The maximum potential liability of the issuers of some U.S. government securities held by the Fund may greatly exceed their current resources, and it is possible that these issuers will not have the funds to meet their payment obligations in the future. In such a case, the Fund would have to look principally to the agency, instrumentality or sponsored enterprise issuing or guaranteeing the security for ultimate repayment, and the Fund may not be able to assert a claim against the U.S. government itself in the event the agency, instrumentality or sponsored enterprise does not meet its commitment. Concerns about the capacity or willingness of the U.S. government to meet its obligations may raise the interest rates payable on its securities, negatively impacting the price of such securities already held by the Fund.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | When-Issued, Delayed Delivery and Forward Commitment Securities Risk [Member]

rr_RiskTextBlock

Agency Securities Risk: Certain debt securities issued or guaranteed by agencies of the U.S. government are guaranteed as to the payment of principal and interest by the relevant entity but have not been backed by the full faith and credit of the U.S. government. Instead, they have been supported only by the discretionary authority of the U.S. government to purchase the agency’s obligations. An event affecting the guaranteeing entity could adversely affect the payment of principal or interest or both on the security and, therefore, these types of securities should be considered to be riskier than U.S. government securities.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Credit Risk [Member]

rr_RiskTextBlock

When-Issued, Delayed Delivery and Forward Commitment Securities Risk: Securities purchased on a forward commitment or when-issued or delayed delivery basis are subject to changes in value, generally changing in the same way (i.e., appreciating when interest rates decline and depreciating when interest rates rise), based upon the public’s perception of the creditworthiness of the issuer and changes, real or anticipated, in the level of interest rates. Securities so purchased may expose the Fund to risks because they may experience such fluctuations prior to their actual delivery. Purchasing securities on a when-issued or delayed delivery basis can involve the additional risk that the yield available in the market when the delivery takes place actually may be higher than that obtained in the transaction itself. Purchasing securities on a forward commitment or when-issued or delayed delivery basis when the Fund is fully or almost fully invested may result in greater potential fluctuation in the value of the Fund’s net assets. This may also occur when the Fund seeks to remain fully invested during the period after purchase but before settlement. In addition, there is a risk that securities purchased on a when-issued or delayed delivery basis may not be delivered and that the purchaser of securities sold by the Fund on a forward commitment basis will not honor its purchase obligation. In such cases, the Fund may incur a loss.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Models and Data Risk [Member]

rr_RiskTextBlock

Credit Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Portfolio Turnover Rate Risk [Member]

rr_RiskTextBlock

Models and Data Risk: The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, the models may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses for the Fund. Models may be predictive in nature and such models may result in an incorrect assessment of future events. Data used in the construction of models may prove to be inaccurate or stale, which may result in losses for the Fund.

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Bloomberg U.S. Aggregate Bond Index

rr_RiskTextBlock

Portfolio Turnover Rate Risk: The Fund may engage in active and frequent trading of portfolio securities to pursue its principal investment strategy. A high rate of portfolio turnover may involve correspondingly greater expenses, which must be borne by the Fund and its shareholders, and also may result in short-term capital gains or losses to shareholders.

rr_ProspectusTable

rr_AverageAnnualReturnYear01

5.53%

^[8]

rr_AverageAnnualReturnYear05

1.10%

^[8]

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Bloomberg U.S. 1-5 Year Government Bond Index

rr_AverageAnnualReturnYear10

1.81%

^[8]

rr_ProspectusTable

rr_AverageAnnualReturnYear01

4.39%

rr_AverageAnnualReturnYear05

1.18%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class A

rr_AverageAnnualReturnYear10

1.13%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.25%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

^[9]

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.20%

^[10]

rr_ExpensesOverAssets

0.77%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.07%

^{[11],[12],[13]}

rr_NetExpensesOverAssets

0.70%

rr_ExpenseExampleYear01

$ 295

rr_ExpenseExampleYear03

459

rr_ExpenseExampleYear05

636

rr_ExpenseExampleYear10

$ 1,151

rr_AverageAnnualReturnYear01

2.56%

rr_AverageAnnualReturnYear05

0.55%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class C

rr_AverageAnnualReturnYear10

0.72%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

1.00%

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

1.00%

rr_OtherExpensesOverAssets

0.21%

rr_ExpensesOverAssets

1.53%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[11],[12]

rr_NetExpensesOverAssets

1.45%

rr_ExpenseExampleYear01

$ 248

rr_ExpenseExampleYear03

476

rr_ExpenseExampleYear05

827

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleYear10

1,611

rr_ExpenseExampleNoRedemptionYear01

148

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

476

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

827

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,611

rr_AverageAnnualReturnYear01

3.18%

rr_AverageAnnualReturnYear05

0.28%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class N

rr_AverageAnnualReturnYear10

0.35%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.11%

rr_ExpensesOverAssets

0.43%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.03%

^[11],[12]

rr_NetExpensesOverAssets

0.40%

rr_ExpenseExampleYear01

$ 41

rr_ExpenseExampleYear03

135

rr_ExpenseExampleYear05

238

rr_ExpenseExampleYear10

$ 539

rr_AverageAnnualReturnYear01

5.17%

rr_AverageAnnualReturnYear05

1.34%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class N | Bloomberg U.S. Aggregate Bond Index

rr_AverageAnnualReturnSinceInception

1.34%

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class N | Bloomberg U.S. 1-5 Year Government Bond Index

rr_AverageAnnualReturnSinceInception

1.27%

^[8]

rr_ProspectusTable

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class T

rr_AverageAnnualReturnSinceInception

1.15%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

2.50%

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

0.25%

rr_OtherExpensesOverAssets

0.20%

^[14]

rr_ExpensesOverAssets

0.77%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.07%

^[11],[12]

rr_NetExpensesOverAssets

0.70%

rr_ExpenseExampleYear01

$ 320

rr_ExpenseExampleYear03

483

rr_ExpenseExampleYear05

660

rr_ExpenseExampleYear10

$ 1,174

rr_AverageAnnualReturnYear01

2.27%

rr_AverageAnnualReturnYear05

0.50%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class Y

rr_AverageAnnualReturnYear10

0.70%

Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price)

rr_ProspectusTable

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Redemption Fee (as a percentage of Amount Redeemed)

rr_MaximumDeferredSalesChargeOverOther

none

rr_RedemptionFeeOverRedemption

none

rr_ManagementFeesOverAssets

0.32%

rr_DistributionAndService12b1FeesOverAssets

none

rr_OtherExpensesOverAssets

0.21%

rr_ExpensesOverAssets

0.53%

Total Annual Fund Operating Expenses After Expense Reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[11],[12]

rr_NetExpensesOverAssets

0.45%

rr_ExpenseExampleYear01

$ 46

rr_ExpenseExampleYear03

162

rr_ExpenseExampleYear05

288

Highest Quarterly Return, Label

rr_ExpenseExampleYear10

$ 657

Annual Return 2014

rr_AnnualReturn2014

1.87%

Annual Return 2015

rr_AnnualReturn2015

0.47%

Annual Return 2016

rr_AnnualReturn2016

0.95%

Annual Return 2017

rr_AnnualReturn2017

1.09%

Annual Return 2018

rr_AnnualReturn2018

1.39%

Annual Return 2019

rr_AnnualReturn2019

3.48%

Annual Return 2020

rr_AnnualReturn2020

3.43%

Annual Return 2021

rr_AnnualReturn2021

(0.99%)

Annual Return 2022

rr_AnnualReturn2022

(4.41%)

Annual Return 2023

rr_AnnualReturn2023

5.22%

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return:

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

2.95%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Dec. 31, 2023

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return:

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(2.45%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2022

rr_AverageAnnualReturnYear01

5.22%

rr_AverageAnnualReturnYear05

1.28%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class Y | Return After Taxes on Distributions

rr_AverageAnnualReturnYear10

1.22%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

3.57%

rr_AverageAnnualReturnYear05

0.46%

Loomis Sayles Funds II | (Loomis Sayles Limited Term Government and Agency Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

rr_AverageAnnualReturnYear10

0.38%

rr_ProspectusTable

rr_AverageAnnualReturnYear01

3.06%

rr_AverageAnnualReturnYear05

0.63%