XML 14 R9.htm IDEA: XBRL DOCUMENT v3.7.0.1
Label Element Value
(Loomis Sayles Multi-Asset Income Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks current income with a secondary objective of 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 and hold shares of the Fund. 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 Fund 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 117 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 Fund 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, 2018
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 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. 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 341% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 341.00%
Strategy [Heading] rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Fund intends to pursue its investment goal by utilizing a flexible investment approach that allocates investments across a broad range of income-producing securities, while employing risk management strategies to mitigate downside risk. The Fund may invest in equity securities (including common stocks, preferred stocks, depositary receipts, warrants, securities convertible into common or preferred stocks and real estate investment trusts ("REITS")). The Fund may also invest up to 25% of its assets in publicly traded master limited partnerships ("MLPs"). The Fund may invest in fixed-income securities (including exchange-traded notes, structured notes, corporate debt, foreign and U.S. government and agency fixed-income securities, bank loans, adjustable floating rate loans and other floating rate debt instruments issued by U.S. and non-U.S. corporations and other business entities and convertible debt securities). The Fund may invest 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 Standard and Poor's Ratings Group ("S&P")), have rated the securities in one of its top four rating categories) or, if unrated, are determined by Loomis Sayles & Company, L.P. ("Loomis Sayles" or the "Subadviser") to be of comparable quality. There is no minimum rating for the fixed-income securities in which the Fund may invest. The Fund may invest in securities of any maturity or market capitalization. The Fund may invest in foreign securities including those in emerging markets.

The Fund may shift its assets among various types of income-producing securities based upon the Subadviser's evaluation of changing market conditions, yield expectations and security-specific opportunities. Changes to the Fund's asset allocations are based on several criteria, including global market cycles, global economic regimes and the relative attractiveness of particular asset categories. Under normal market conditions, the Fund will typically invest between 20% and 80% of its assets in fixed-income securities and between 30% and 70% in equity securities. However, the Fund is not required to allocate its investments among asset classes in any fixed proportion and may invest up to 100% of its assets in either equity securities or fixed-income securities. A sudden change in market conditions could cause the Subadviser to substantially change the allocation of the Fund's assets over a relatively short period of time.

In selecting individual investments for the Fund, the Subadviser considers factors including, but not limited to, economic and business cycles as well as top-down sector valuations and fundamental, bottom-up security valuations. In deciding which equity securities to buy and sell, the Subadviser seeks to identify securities that it believes are, among other things, attractively valued based on the Subadviser's estimate of what a security is actually worth, with additional consideration given to income-producing securities. The Subadviser may utilize quantitative screening methods based on fundamental factors to identify issuers which may pay or grow dividends.

In deciding which fixed-income securities to buy and sell, the Subadviser may consider a number of factors including, but not limited to, diverging business cycles among countries and regions, the stability and volatility of a country's bond markets, the financial strength of the issuer, current interest rates, the Subadviser's expectations regarding general trends in interest rates and currency considerations. The Subadviser will also consider how purchasing or selling a security would impact the overall portfolio's risk profile (for example, its sensitivity to currency risk, interest rate risk and sector-specific risk) and potential return (income and capital gains).

When constructing the Fund's portfolio the Subadviser will use risk management tools in an effort to manage risk on an ongoing basis. These tools include the use of models that evaluate risk correlation to various market factors or asset classes, scenario analysis to measure the impact of certain market events and measuring the volatility of certain sectors and securities to understand the level of risk being contributed by these sectors and securities. The portfolio management team expects to actively evaluate each investment idea and to decide to buy or sell an investment based upon: (i) its return potential; (ii) its level of risk; and (iii) its fit within the team's overall macro strategy, with the goal of continually optimizing the Fund's portfolio.

The Fund may also:

• Invest in mortgage-related and asset-backed securities

• Invest in securities offered in initial public offerings ("IPOs") and securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Rule 144A securities are privately offered securities and can be resold only to certain qualified institutional buyers.

• Engage in over-the-counter ("OTC") options, swap contracts (including credit default swaps) and currency transactions as well as futures transactions and other derivatives for hedging and investment purposes. The Fund may take both long and short positions in derivatives.

• Engage in active and frequent trading of securities and other instruments. Effects of frequent trading may include high transaction costs, which may lower the Fund's returns, and realization of short-term capital gains, distributions of which are taxable to shareholders who are individuals as ordinary income. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance.
Risk [Heading] rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

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

Credit/Counterparty Risk: Credit/counterparty risk is the risk that the issuer or guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. The Fund will be subject to credit risks with respect to the counterparties of its derivative transactions. Many of the protections afforded to participants on organized exchanges, such as the performance guarantee of an exchange clearing house, are not available in connection with OTC derivative transactions, such as foreign currency transactions. As a result, in instances when the Fund enters into OTC derivative transactions, the Fund will be subject to the risk that its counterparties will not perform their obligations under the transactions and that the Fund will sustain losses or be unable to realize gains.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including options, foreign currency transactions, futures transactions and swap transactions) 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 markets 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 the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other OTC traded 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 the initial margin required to initiate derivatives positions. There is also the risk that the Fund may be unable to terminate or sell a derivatives 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.

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. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. Rule 144A securities may be less liquid than other equity securities. 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.

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.

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. In addition, an economic downturn or period of rising interest rates could adversely affect the markets for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

Leverage Risk: Use of derivative instruments may involve leverage. Leverage is the risk associated with securities or practices 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 a fund's returns, and may lead to significant losses if investments are not successful.

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. 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. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to greater 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. Non-exchange traded derivatives are generally subject to greater liquidity risk as well. Liquidity issues may also make it difficult to value the Fund's investments.

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

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.

Master Limited Partnership Risk: Investments in MLPs involve risks in addition to the risks associated with investments in securities with similar characteristics, such as common stock of a corporation. Holders of common interests in MLPs typically have limited control and limited rights to vote on matters affecting the MLP. Conflicts of interest may also exist between an MLP's common interest holders and its general partner or managing member, including those arising from incentive distribution payments. Many interests in MLPs are subject to restrictions on resale and may therefore be less liquid than other investments, which may subject MLP interests to more abrupt or erratic price movements and may increase the difficulty of disposing of such interests at favorable times and prices. The Fund may gain exposure to MLPs through derivatives, including exchange-traded notes ("ETNs") and swaps, exposing the Fund to the risks of investing in derivatives generally. MLPs often own interests in energy infrastructure properties, including pipelines, or engage in activities related to the energy sector. Accordingly, to the extent the Fund invests in MLPs, it will likely be exposed to risks related to investments in the energy sector. In addition, if an MLP fails to meet the current legal requirements for treatment as a partnership, or if there are changes to the tax laws, an MLP could be treated as a corporation for U.S. federal income tax purposes, obligating the MLP to pay tax at the entity level and significantly reducing the income to the Fund from an investment in an MLP. The Fund's pursuit of its investment strategy will potentially be limited by the Fund's intention to qualify for the special tax treatment accorded a registered investment company and its shareholders and could adversely affect the Fund.

Mortgage-Related and Asset-Backed Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity 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.

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.

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.
Risk Lose Money [Text] rr_RiskLoseMoney You may lose money by investing in the Fund.
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 measure of market performance. 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 ngam.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.
Bar Chart [Heading] rr_BarChartHeading

Total Returns for Class A 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.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Highest Quarterly Return:
Second Quarter 2009, 18.28%

Lowest Quarterly Return:
Fourth Quarter 2008, -18.23%
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns

(for the periods ended December 31, 2016)

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

Prior to the stock market close August 31, 2015, the Fund had multiple subadvisers. The performance results shown above for the periods prior to the stock market close August 31, 2015 reflect results achieved by those subadvisers using different investment strategies.

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 in the table 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 Fund 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.
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 Fund shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans or individual retirement accounts.
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.
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 measure of market performance.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ngam.natixis.com
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
(Loomis Sayles Multi-Asset Income Fund) | Bloomberg Barclays U.S. Aggregate Bond Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 2.65%
Past 5 Years rr_AverageAnnualReturnYear05 2.23%
Past 10 Years rr_AverageAnnualReturnYear10 4.34%
Life of Fund rr_AverageAnnualReturnSinceInception 2.06%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2015
(Loomis Sayles Multi-Asset Income Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 4.25%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none [1]
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.55%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.29%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.13% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.22%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.14% [3],[4]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.08%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 530
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 782
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,054
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,828
Annual Return 2007 rr_AnnualReturn2007 (2.80%)
Annual Return 2008 rr_AnnualReturn2008 (25.26%)
Annual Return 2009 rr_AnnualReturn2009 33.32%
Annual Return 2010 rr_AnnualReturn2010 16.73%
Annual Return 2011 rr_AnnualReturn2011 7.21%
Annual Return 2012 rr_AnnualReturn2012 13.22%
Annual Return 2013 rr_AnnualReturn2013 5.84%
Annual Return 2014 rr_AnnualReturn2014 13.08%
Annual Return 2015 rr_AnnualReturn2015 (1.96%)
Annual Return 2016 rr_AnnualReturn2016 10.14%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return: Second Quarter 2009, 18.28%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.28%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return: Fourth Quarter 2008, -18.23%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (18.23%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Past 1 Year rr_AverageAnnualReturnYear01 5.46%
Past 5 Years rr_AverageAnnualReturnYear05 6.97%
Past 10 Years rr_AverageAnnualReturnYear10 5.44%
(Loomis Sayles Multi-Asset Income Fund) | Class A | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 3.55%
Past 5 Years rr_AverageAnnualReturnYear05 5.85%
Past 10 Years rr_AverageAnnualReturnYear10 4.17%
(Loomis Sayles Multi-Asset Income Fund) | Class A | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 4.15%
Past 5 Years rr_AverageAnnualReturnYear05 5.14%
Past 10 Years rr_AverageAnnualReturnYear10 3.84%
(Loomis Sayles Multi-Asset Income Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.55%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.29%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.13% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.97%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.14% [3],[4]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.83%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 286
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 605
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,049
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,285
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 186
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 605
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,049
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,285
Past 1 Year rr_AverageAnnualReturnYear01 8.27%
Past 5 Years rr_AverageAnnualReturnYear05 7.09%
Past 10 Years rr_AverageAnnualReturnYear10 5.09%
(Loomis Sayles Multi-Asset Income Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.55%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 12.98%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.13% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 13.66%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 12.88% [3],[4]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 0.78%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 80
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 2,686
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 4,860
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 8,847
Past 1 Year rr_AverageAnnualReturnYear01 10.53%
Life of Fund rr_AverageAnnualReturnSinceInception 9.33%
Inception Date rr_AverageAnnualReturnInceptionDate Aug. 31, 2015
(Loomis Sayles Multi-Asset Income Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.55%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.29% [5]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.13% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 1.22%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.14% [3],[4]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.08%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 357
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 613
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 889
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,677
Past 1 Year rr_AverageAnnualReturnYear01 7.38%
Past 5 Years rr_AverageAnnualReturnYear05 7.36%
Past 10 Years rr_AverageAnnualReturnYear10 5.63%
(Loomis Sayles Multi-Asset Income Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.55%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.29%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.13% [2]
Total annual fund operating expenses rr_ExpensesOverAssets 0.97%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.14% [3],[4]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 0.83%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 85
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 295
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 523
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,177
Past 1 Year rr_AverageAnnualReturnYear01 10.38%
Past 5 Years rr_AverageAnnualReturnYear05 8.03% [6]
Past 10 Years rr_AverageAnnualReturnYear10 5.96% [6]
(Mirova Global Sustainable Equity Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks long-term 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 and hold shares of the Fund. 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 Fund 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 117 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 Fund 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, 2018
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. 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 the period March 31, 2016 through December 31, 2016, the Fund's portfolio turnover rate was 20% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 20.00%
Strategy [Heading] rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Under normal circumstances, the Fund invests at least 80% of its assets in equity securities, which may include common stocks, preferred stocks, depositary receipts and real estate investment trusts ("REITS"). The Fund invests in securities of companies located in no fewer than three countries, which may include the U.S. Under normal circumstances, the Fund will invest at least 40% of its assets in securities of companies located outside the U.S. and the Fund may invest up to 25% of its assets in securities of companies located in emerging markets. Emerging markets are economies that the Adviser believes are not generally recognized to be fully developed markets, as measured by gross national income, financial market infrastructure, market capitalization and/or other factors. The Fund may invest in growth and value companies of any size and may also invest in initial public offerings.

The Adviser pursues the Fund's investment goal by investing in equity securities of companies that it expects will benefit from major long-term global trends. The Adviser believes that there are several long-term trends that can reshape the world now and in the future. These trends include those that are demographic in nature, such as population growth and an aging population, and others that are more socioeconomic, such as urbanization, evolving consumption in emerging markets and a changing global financial model. In addition, there are environmental trends such as climate change and natural resource depletion, as well as trends driven by technological innovation. In selecting companies to invest in, the Adviser focuses on providers of solutions to the issues arising from these trends, as well as companies that provide products and services that address or are otherwise aligned with these trends and the need to create a more sustainable world.

The Adviser selects securities based on an in-depth fundamental analysis of companies combining qualitative, financial and environmental, social and governance ("ESG") considerations. The Adviser emphasizes company-specific positive selection criteria over broad-based negative screens in assessing ESG practices. This means that the Adviser's research process is designed to prioritize investments in companies which it believes show good ESG practices and whose products and services help create a more sustainable world, rather than merely excluding companies which the Adviser believes show poor ESG practices. Nevertheless, as ESG criteria are integrated in the Fund's risk management process, the Adviser also seeks to avoid investing in companies which do not comply with the Adviser's minimum ESG standards. In deciding which securities to buy and sell, the Adviser generally seeks to invest in securities of companies that:

  • relate to sustainable development themes derived from long-term global trends, providing solutions to address issues related to energy, mobility, building and cities, management of natural resources, consumption, healthcare, information technology or finance;

  • demonstrate adherence to ESG practices, with respect to such issues as fair labor, anti-corruption, human rights, fair business practices and mitigation of environmental impact;

  • have strong fundamentals, including sustainable business models, competitive positioning, effective management teams, acceptable risk profiles, and long-term growth potential; and

  • offer attractive valuations.

In determining whether or not a company's risk profile is acceptable, the Adviser seeks to evaluate risks that may affect share price in the long-term, such as market, environmental, exchange rate, political, and reputation risks, among others. If the risk profile of a company is too high, the investment team may decide not to invest and/or sell a security and look for alternatives.

It is expected that the Adviser's views on long-term global trends and sustainable development themes will evolve over time.
Risk [Heading] rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

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 invests 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.

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, nationalization or confiscatory taxation, currency exchange restrictions, sanctions by the U.S. government and an issuer's unwillingness or inability to make principal or interest payments on its obligations. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

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. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. 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.

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.

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.

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

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.

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.

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.

Sustainable Investment Style Risk: Because the Fund focuses on investments in companies that relate to certain sustainable development themes and demonstrate adherence to ESG practices, its universe of investments may be smaller than that of other funds and therefore the Fund may underperform the market as a whole if such investments underperform the market. The Fund may forgo opportunities to gain exposure to certain companies, industries, sectors or countries and it may choose to sell a security when it might otherwise be disadvantageous to do so.
Risk Lose Money [Text] rr_RiskLoseMoney You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading

Risk/Return Bar Chart and Table

Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

Because the Fund has not yet completed a full calendar year, information related to Fund performance, including a bar chart showing annual returns, has not been included in this Prospectus. The performance information provided by the Fund in the future will give some indication of the risks of an investment 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 compare against those of a broad measure of market performance. 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 ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.
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.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The performance information provided by the Fund in the future will give some indication of the risks of an investment 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 compare against those of a broad measure of market performance.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ngam.natixis.com
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
(Mirova Global Sustainable Equity Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none [1]
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.67%
Total annual fund operating expenses rr_ExpensesOverAssets 1.72%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.42% [7],[8]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 700
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 1,047
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,418
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,456
(Mirova Global Sustainable Equity Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.40%
Total annual fund operating expenses rr_ExpensesOverAssets 2.20%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.15% [7],[8]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 2.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 308
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 674
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,166
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,522
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 208
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 674
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,166
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,522
(Mirova Global Sustainable Equity Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.40% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.20%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.20% [7],[8]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.00%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 102
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 361
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 640
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,437
(Mirova Global Sustainable Equity Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.67% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.72%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.42% [7],[8]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.30%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 379
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 735
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,118
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,193
(Mirova Global Sustainable Equity Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.41%
Total annual fund operating expenses rr_ExpensesOverAssets 1.21%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets 0.16% [7],[8]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.05%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 107
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 368
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 650
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,452
(Natixis Oakmark International Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks long-term 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 and hold shares of the Fund. 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 Fund 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 117 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 Fund 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, 2018
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. 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 41% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 41.00%
Strategy [Heading] rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Fund invests primarily in a diversified portfolio of common stocks of non-U.S. companies. The Fund may invest in non-U.S. markets throughout the world, including emerging markets. Ordinarily, the Fund will invest in the securities of at least five countries outside the U.S. There are no geographic limits on the Fund's non-U.S. investments. Although the Fund invests primarily in common stocks of non-U.S. companies it may also invest in the securities of U.S. companies. The Fund may invest in the securities of small-, mid- and large-capitalization companies.

The Fund's subadviser, Harris Associates L.P. ("Harris Associates"), uses a value investment philosophy in selecting equity securities, such as common stocks, preferred stocks, warrants, and securities convertible into common stocks and preferred stocks. This investment philosophy is based upon the belief that, over time, a company's stock price converges with Harris Associates' estimate of its intrinsic or true business value. By "true business value," Harris Associates means its estimate of the price a knowledgeable buyer would pay to acquire the entire business. Harris Associates believes that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objective.

Harris Associates uses this value philosophy to identify companies that it believes have discounted stock prices compared to the companies' true business values. In assessing such companies, Harris Associates looks for the following characteristics, although not all of the companies selected will have these attributes: (1) free cash flows and intelligent investment of excess cash; (2) earnings that are growing and are reasonably predictable; and (3) high level of manager ownership.

Once Harris Associates identifies a stock that it believes is selling at a significant discount to Harris Associates' estimated intrinsic value and that the issuer has one or more of the additional qualities mentioned above, Harris Associates generally will consider buying that security for the Fund. Harris Associates usually sells a security when the price approaches its estimated worth or the issuer's fundamentals change. Harris Associates monitors each holding and adjusts its price targets as warranted to reflect changes in the issuer's fundamentals. The Fund's portfolio typically holds 30 to 65 stocks.
Risk [Heading] rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

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.

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, nationalization or confiscatory taxation, currency exchange restrictions, sanctions by the U.S. government and an issuer's unwillingness or inability to make principal or interest payments on its obligations. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

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. 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. Small- and mid-capitalization and emerging growth companies may be subject to more abrupt price movements, limited markets and less liquidity than larger, more established companies, which could adversely affect the value of the Fund's equity portfolio.

Focused Investment Risk: Because the Fund may invest in a small number of industries or securities, it may have more risk because the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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.

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

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.

Risk Lose Money [Text] rr_RiskLoseMoney You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading

Risk/Return Bar Chart and Table

Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following bar chart and table 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 total returns for the one-year, five-year and life-of-fund periods compare to those of a broad measure of market performance. 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 ngam.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.
Bar Chart [Heading] rr_BarChartHeading

Total Returns for Class A 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.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Highest Quarterly Return:
First Quarter 2012, 17.17%

Lowest Quarterly Return:
Third Quarter 2011, -20.47%
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns

(for the periods ended December 31, 2016)

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

The Fund did not have Class N, Class T or Class Y shares outstanding during the periods shown above. The returns of Class N, Class T or Class Y 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. Performance of Class Y shares is that of Class A shares and reflects the higher net expenses of that share class.

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 Fund 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.

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 Fund shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
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.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table 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 total returns for the one-year, five-year and life-of-fund periods compare to those of a broad measure of market performance.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ngam.natixis.com
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
(Natixis Oakmark International Fund) | MSCI World ex USA Index (Net)  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 2.75%
Past 5 Years rr_AverageAnnualReturnYear05 6.07%
Life of Fund rr_AverageAnnualReturnSinceInception 3.00%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none [1]
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.85%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.24%
Total annual fund operating expenses rr_ExpensesOverAssets 1.34%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [7],[9]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 704
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 975
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,267
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,095
Annual Return 2011 rr_AnnualReturn2011 (14.55%)
Annual Return 2012 rr_AnnualReturn2012 28.78%
Annual Return 2013 rr_AnnualReturn2013 28.13%
Annual Return 2014 rr_AnnualReturn2014 (6.05%)
Annual Return 2015 rr_AnnualReturn2015 (5.35%)
Annual Return 2016 rr_AnnualReturn2016 8.19%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return: First Quarter 2012, 17.17%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.17%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2012
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return: Third Quarter 2011, -20.47%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (20.47%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Past 1 Year rr_AverageAnnualReturnYear01 1.97%
Past 5 Years rr_AverageAnnualReturnYear05 8.39%
Life of Fund rr_AverageAnnualReturnSinceInception 4.43%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class A | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 1.71%
Past 5 Years rr_AverageAnnualReturnYear05 7.95%
Life of Fund rr_AverageAnnualReturnSinceInception 4.10%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class A | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 1.77%
Past 5 Years rr_AverageAnnualReturnYear05 6.80%
Life of Fund rr_AverageAnnualReturnSinceInception 3.62%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.85%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.24%
Total annual fund operating expenses rr_ExpensesOverAssets 2.09%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [7],[9]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 2.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 312
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 655
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,124
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,421
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 212
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 655
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,124
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,421
Past 1 Year rr_AverageAnnualReturnYear01 6.36%
Past 5 Years rr_AverageAnnualReturnYear05 8.89%
Life of Fund rr_AverageAnnualReturnSinceInception 4.68%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.85%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.12% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 0.97%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [7],[9]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 0.97%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 99
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 309
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 536
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,190
(Natixis Oakmark International Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.85%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.24% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.34%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [7],[9]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.34%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 383
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 664
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 966
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,822
Past 1 Year rr_AverageAnnualReturnYear01 5.52%
Past 5 Years rr_AverageAnnualReturnYear05 9.13%
Life of Fund rr_AverageAnnualReturnSinceInception 5.01%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis Oakmark International Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.85%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.24% [5]
Total annual fund operating expenses rr_ExpensesOverAssets 1.09%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [7],[9]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.09%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 111
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 347
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 601
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,329
Past 1 Year rr_AverageAnnualReturnYear01 8.19%
Past 5 Years rr_AverageAnnualReturnYear05 9.68%
Life of Fund rr_AverageAnnualReturnSinceInception 5.45%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 15, 2010
(Natixis U.S. Equity Opportunities Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks 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 and hold shares of the Fund. 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 Fund 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 117 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 Fund 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, 2018
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. 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 17% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 17.00%
Strategy [Heading] rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Fund ordinarily invests at least 80% of its net assets (plus any borrowings made for investment purposes) in equity securities, including common stocks and preferred stocks. Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in securities of U.S. issuers. The Fund's approach to equity investing combines the styles of two subadvisers in selecting securities for each of the Fund's segments. The segments and their subadvisers are listed below.

  • Harris Associates - Large Cap Value segment - Under normal circumstances, the Large Cap Value segment of the Fund managed by Harris Associates L.P. ("Harris Associates") will invest primarily in the common stocks of larger- capitalization companies that Harris Associates believes are trading at a substantial discount to the company's "true business value." By "true business value," Harris Associates means its estimate of the price a knowledgeable buyer would pay to acquire the entire business. Harris Associates believes that investing in securities priced significantly below their true business value presents the best opportunity to achieve the Fund's investment objectives. Harris Associates usually sells a security when the price approaches its estimated worth and monitors each holding and adjusts its price targets as warranted to reflect changes in the issuer's fundamentals. In determining whether an issuer is a U.S or foreign issuer for the Harris Associates – Large Cap Value segment, Harris Associates considers various factors, including its country of domicile, the primary stock exchange on which it trades, the location from which the majority of its revenue comes, and its reporting currency.

  • Loomis Sayles - All Cap Growth segment - Under normal circumstances, the All Cap Growth segment of the Fund, managed by Loomis, Sayles & Company, L.P. ("Loomis Sayles"), will invest primarily in equity securities, including common stocks, preferred stocks, convertible securities and warrants. This segment may invest in companies of any size. The segment normally invests across a wide range of sectors and industries. The segment's portfolio manager employs a growth style of equity management that emphasizes companies with sustainable competitive advantages, long-term structural growth drivers, attractive cash flow returns on invested capital, and management teams focused on creating long-term value for shareholders. The segment's portfolio manager aims to invest in companies when they trade at a significant discount to the estimate of intrinsic value. The segment 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 portfolio manager believes the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate. Although certain equity securities purchased by the Loomis Sayles – All Cap Growth segment of the Fund may be issued by domestic companies incorporated outside of the United States, Loomis Sayles 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.

Subject to the allocation policy adopted by the Fund's Board of Trustees, NGAM Advisors, L.P. ("NGAM Advisors") generally allocates capital invested in the Fund equally (i.e., 50%) between its two segments. Under the allocation policy, NGAM Advisors may also allocate capital away from or towards each segment from time to time and may reallocate capital between the segments. Each subadviser manages its segment of the Fund's assets in accordance with its distinct investment style and strategy.

The Fund may also:

  • Invest in securities offered in initial public offerings ("IPOs") and securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities").

  • Invest in convertible preferred stock and convertible debt securities.

  • Invest in real estate investment trusts ("REITs").

  • Invest in fixed-income securities, including U.S. government bonds and below-investment grade fixed-income securities (commonly known as "junk bonds").

  • Hold securities of foreign issuers traded over-the-counter or on foreign exchanges, including securities in emerging markets and related currency hedging transactions.

  • Invest in equity securities of Canadian issuers.
Risk [Heading] rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

Allocation Risk: The Fund's investment performance depends on how its assets are allocated. The allocation, as set forth above, may not be optimal in every market condition. You could lose money on your investment in the Fund as a result of this allocation.

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

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, nationalization or confiscatory taxation, currency exchange restrictions, sanctions by the U.S. government and an issuer's unwillingness or inability to make principal or interest payments on its obligations. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

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. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. 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 subadviser's assessment of the prospects for a company's growth is wrong, or if the subadviser'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 subadviser 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.

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.

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. 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. Securities acquired in a private placement, such as Rule 144A securities, are generally subject to greater 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. Non-exchange traded derivatives are generally subject to greater liquidity risk as well. Liquidity issues may also make it difficult to value the Fund's investments.

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

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.

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.

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.
Risk Lose Money [Text] rr_RiskLoseMoney You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading

Risk/Return Bar Chart and Table

Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following bar chart and table 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 two broad measures of market performance. The Russell 1000® Index is an unmanaged index that measures the performance of the large-capitalization segment of the U.S. equity universe. A subset of the Russell 3000® Index, it includes approximately 1,000 of the largest stocks based on a combination of market capitalization and current index membership. 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 ngam.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.
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.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Highest Quarterly Return:
Third Quarter 2009, 17.90%

Lowest Quarterly Return:
Fourth Quarter 2008, -24.12%
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns

(for the periods ended December 31, 2016)

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

The Fund uses multiple subadvisers. The performance results shown above reflect results achieved by previous subadvisers using different investment strategies.

The Fund did not have Class N or Class T shares outstanding during the periods shown above. The returns of Class N and 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. Prior to May 1, 2017, Total Returns in the bar chart and Return After Taxes on Distributions and Return After Taxes on Distributions & Sale of Fund Shares in the table were presented for Class A shares; such returns are now presented for Class Y shares, the largest share class in the Natixis Fund Complex.

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 Fund 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.
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 Fund shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
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.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table 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 two broad measures of market performance.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ngam.natixis.com
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
(Natixis U.S. Equity Opportunities Fund) | S&P 500® Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 11.96%
Past 5 Years rr_AverageAnnualReturnYear05 14.66%
Past 10 Years rr_AverageAnnualReturnYear10 6.95%
(Natixis U.S. Equity Opportunities Fund) | Russell 1000® Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 12.05%
Past 5 Years rr_AverageAnnualReturnYear05 14.69%
Past 10 Years rr_AverageAnnualReturnYear10 7.08%
(Natixis U.S. Equity Opportunities Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none [1]
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Fee/expense recovery rr_Component1OtherExpensesOverAssets none [10]
Remainder of other expenses rr_Component2OtherExpensesOverAssets 0.18%
Other expenses rr_OtherExpensesOverAssets 0.18%
Total annual fund operating expenses rr_ExpensesOverAssets 1.23%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[11]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.23%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 693
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 943
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,212
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,978
Past 1 Year rr_AverageAnnualReturnYear01 5.44%
Past 5 Years rr_AverageAnnualReturnYear05 15.04%
Past 10 Years rr_AverageAnnualReturnYear10 8.30%
(Natixis U.S. Equity Opportunities Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Fee/expense recovery rr_Component1OtherExpensesOverAssets none [10]
Remainder of other expenses rr_Component2OtherExpensesOverAssets 0.18%
Other expenses rr_OtherExpensesOverAssets 0.18%
Total annual fund operating expenses rr_ExpensesOverAssets 1.98%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[11]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.98%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 301
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 621
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,068
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,306
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 201
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 621
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,068
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,306
Past 1 Year rr_AverageAnnualReturnYear01 10.02%
Past 5 Years rr_AverageAnnualReturnYear05 15.55%
Past 10 Years rr_AverageAnnualReturnYear10 8.13%
(Natixis U.S. Equity Opportunities Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Fee/expense recovery rr_Component1OtherExpensesOverAssets none [10]
Remainder of other expenses rr_Component2OtherExpensesOverAssets 0.09% [12]
Other expenses rr_OtherExpensesOverAssets 0.09%
Total annual fund operating expenses rr_ExpensesOverAssets 0.89%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[11]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 0.89%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 91
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 284
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 493
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,096
(Natixis U.S. Equity Opportunities Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Fee/expense recovery rr_Component1OtherExpensesOverAssets none [10]
Remainder of other expenses rr_Component2OtherExpensesOverAssets 0.18% [12]
Other expenses rr_OtherExpensesOverAssets 0.18%
Total annual fund operating expenses rr_ExpensesOverAssets 1.23%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[11]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.23%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 372
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 631
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 909
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,702
Past 1 Year rr_AverageAnnualReturnYear01 9.05%
Past 5 Years rr_AverageAnnualReturnYear05 15.83%
Past 10 Years rr_AverageAnnualReturnYear10 8.67%
(Natixis U.S. Equity Opportunities Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.80%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Fee/expense recovery rr_Component1OtherExpensesOverAssets none [10]
Remainder of other expenses rr_Component2OtherExpensesOverAssets 0.18%
Other expenses rr_OtherExpensesOverAssets 0.18%
Total annual fund operating expenses rr_ExpensesOverAssets 0.98%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[11]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 0.98%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 100
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 312
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 542
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,201
Annual Return 2007 rr_AnnualReturn2007 14.02%
Annual Return 2008 rr_AnnualReturn2008 (39.89%)
Annual Return 2009 rr_AnnualReturn2009 36.71%
Annual Return 2010 rr_AnnualReturn2010 22.21%
Annual Return 2011 rr_AnnualReturn2011 (2.56%)
Annual Return 2012 rr_AnnualReturn2012 18.15%
Annual Return 2013 rr_AnnualReturn2013 36.06%
Annual Return 2014 rr_AnnualReturn2014 13.25%
Annual Return 2015 rr_AnnualReturn2015 6.11%
Annual Return 2016 rr_AnnualReturn2016 12.13%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return: Third Quarter 2009, 17.90%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 17.90%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return: Fourth Quarter 2008, -24.12%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.12%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Dec. 31, 2008
Past 1 Year rr_AverageAnnualReturnYear01 12.13%
Past 5 Years rr_AverageAnnualReturnYear05 16.72%
Past 10 Years rr_AverageAnnualReturnYear10 9.23%
(Natixis U.S. Equity Opportunities Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 11.62%
Past 5 Years rr_AverageAnnualReturnYear05 14.23%
Past 10 Years rr_AverageAnnualReturnYear10 7.95%
(Natixis U.S. Equity Opportunities Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 7.25%
Past 5 Years rr_AverageAnnualReturnYear05 13.06%
Past 10 Years rr_AverageAnnualReturnYear10 7.34%
(Vaughan Nelson Small Cap Value Fund)  
Prospectus: rr_ProspectusTable  
Objective [Heading] rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The Fund seeks capital appreciation.
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. 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 Fund 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 117 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 Fund 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, 2018
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 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. 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 74% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 74.00%
Strategy [Heading] rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in the equity securities, including common stocks and preferred stocks, of "small-capitalization companies." Equity securities may take the form of stock in corporations, limited partnership interests, interests in limited liability companies, real estate investment trusts ("REITs") or other trusts and other similar securities. Currently, the Fund defines a small-capitalization company to be one whose market capitalization, at the time of purchase, either falls within the capitalization range of the Russell 2000® Value Index, an unmanaged index that measures the performance of those Russell 2000® companies with lower price-to-book ratios and lower forecasted growth values, or is $3.5 billion or less. While the market capitalization range for the Russell 2000® Value Index fluctuates, at December 31, 2016, it was $35.6 million to $10.3 billion. The Fund may, however, invest in companies with large- capitalizations.

Vaughan Nelson Investment Management, L.P. ("Vaughan Nelson") invests in small-capitalization companies with a focus on those companies meeting Vaughan Nelson's return expectations. Vaughan Nelson uses a bottom-up value oriented investment process in constructing the Fund's portfolio. Vaughan Nelson seeks companies with the following characteristics, although not all of the companies selected will have these attributes:

  • Companies earning a positive return on capital with stable-to-improving returns.

  • Companies valued at a discount to their asset value.

  • Companies with an attractive and sustainable dividend level.

In selecting investments for the Fund, Vaughan Nelson generally employs the following strategies:

  • Value-driven investment philosophy that selects stocks selling at a relatively low value based on discounted cash flow models. Vaughan Nelson selects companies that it believes are out of favor or misunderstood.

  • Vaughan Nelson starts with an investment universe of 5,000 securities. Vaughan Nelson then uses value-driven screens to create a research universe of companies with market capitalizations of at least $100 million.

  • Vaughan Nelson uses fundamental analysis to construct a portfolio of 60 to 80 securities that, in the opinion of Vaughan Nelson, is made up of quality companies with the potential to provide significant increases in share price over a three year period.

  • Vaughan Nelson will generally sell a security when it reaches Vaughan Nelson's price target or when the issuer shows a change in financial condition, competitive pressures, poor management decisions or internal or external forces reducing future expected returns from the investment thesis.

The Fund may also:

  • Invest in convertible preferred stock and convertible debt securities.

  • Invest in foreign securities, including emerging market securities.

  • Invest in REITs.

  • Invest in securities offered in initial public offerings ("IPOs").
Risk [Heading] rr_RiskHeading

Principal Investment Risks

Risk Narrative [Text Block] rr_RiskNarrativeTextBlock

The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund.

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, nationalization or confiscatory taxation, currency exchange restrictions, sanctions by the U.S. government and an issuer's unwillingness or inability to make principal or interest payments on its obligations. Emerging markets companies may be smaller and have shorter operating histories than companies in developed markets.

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. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. 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.

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.

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. 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. Liquidity issues may also make it difficult to value the Fund's investments.

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

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.

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.

Small-Capitalization Companies Risk: Small-capitalization companies are more likely than larger companies to have limited product lines, markets or financial resources, or to depend on a small, inexperienced management group. Stocks of these companies often trade less frequently and in limited volume and their prices may fluctuate more than stocks of larger companies. Stocks of small-capitalization companies may therefore be more vulnerable to adverse developments than those of larger companies.
Risk Lose Money [Text] rr_RiskLoseMoney You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading

Risk/Return Bar Chart and Table

Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following bar chart and table 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 measure of market performance. 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 ngam.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.
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.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

Highest Quarterly Return:
Third Quarter 2009, 18.63%

Lowest Quarterly Return:
Third Quarter 2011, -19.51%
Performance Table Heading rr_PerformanceTableHeading

Average Annual Total Returns

(for the periods ended December 31, 2016)

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock

The Fund did not have Class N or Class T shares outstanding during the periods shown above. The returns of Class N and 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. Prior to May 1, 2017, Total Returns in the bar chart and Return After Taxes on Distributions and Return After Taxes on Distributions & Sale of Fund Shares in the table were presented for Class A shares; such returns are now presented for Class Y shares, the largest share class in the Natixis Fund Complex.

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 Fund 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.
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 Fund shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
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.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table 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 measure of market performance.
Performance Table One Class of after Tax Shown [Text] rr_PerformanceTableOneClassOfAfterTaxShown The after-tax returns are shown for only one class of the Fund.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress ngam.natixis.com
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone 800-225-5478
(Vaughan Nelson Small Cap Value Fund) | Russell 2000® Value Index  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 31.74%
Past 5 Years rr_AverageAnnualReturnYear05 15.07%
Past 10 Years rr_AverageAnnualReturnYear10 6.26%
(Vaughan Nelson Small Cap Value Fund) | Class A  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none [1]
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.90%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.20%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.18% [13]
Total annual fund operating expenses rr_ExpensesOverAssets 1.53%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[14]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.53%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 722
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 1,031
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,361
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,294
Past 1 Year rr_AverageAnnualReturnYear01 13.34%
Past 5 Years rr_AverageAnnualReturnYear05 14.46%
Past 10 Years rr_AverageAnnualReturnYear10 9.62%
(Vaughan Nelson Small Cap Value Fund) | Class C  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther 1.00%
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.90%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other expenses rr_OtherExpensesOverAssets 0.20%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.18% [13]
Total annual fund operating expenses rr_ExpensesOverAssets 2.28%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[14]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 2.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 331
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 712
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,220
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 2,615
Expense Example, No Redemption, 1 Year rr_ExpenseExampleNoRedemptionYear01 231
Expense Example, No Redemption, 3 Years rr_ExpenseExampleNoRedemptionYear03 712
Expense Example, No Redemption, 5 Years rr_ExpenseExampleNoRedemptionYear05 1,220
Expense Example, No Redemption, 10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,615
Past 1 Year rr_AverageAnnualReturnYear01 18.32%
Past 5 Years rr_AverageAnnualReturnYear05 14.95%
Past 10 Years rr_AverageAnnualReturnYear10 9.44%
(Vaughan Nelson Small Cap Value Fund) | Class N  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.90%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.11% [5]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.18% [13]
Total annual fund operating expenses rr_ExpensesOverAssets 1.19%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[14]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.19%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 121
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 378
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 654
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,443
(Vaughan Nelson Small Cap Value Fund) | Class T  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 2.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.90%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other expenses rr_OtherExpensesOverAssets 0.20% [5]
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.18% [13]
Total annual fund operating expenses rr_ExpensesOverAssets 1.53%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[14]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.53%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 402
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 721
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 1,063
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 2,028
Past 1 Year rr_AverageAnnualReturnYear01 17.27%
Past 5 Years rr_AverageAnnualReturnYear05 15.24%
Past 10 Years rr_AverageAnnualReturnYear10 9.98%
(Vaughan Nelson Small Cap Value Fund) | Class Y  
Prospectus: rr_ProspectusTable  
Maximum sales charge (load) imposed on purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable) rr_MaximumDeferredSalesChargeOverOther none
Redemption fees rr_RedemptionFee none
Management fees rr_ManagementFeesOverAssets 0.90%
Distribution and/or service (12b-1) fees rr_DistributionAndService12b1FeesOverAssets none
Other expenses rr_OtherExpensesOverAssets 0.20%
Acquired fund fees and expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.18% [13]
Total annual fund operating expenses rr_ExpensesOverAssets 1.28%
Fee waiver and/or expense reimbursement rr_FeeWaiverOrReimbursementOverAssets none [3],[14]
Total annual fund operating expenses after fee waiver and/or expense reimbursement rr_NetExpensesOverAssets 1.28%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 130
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 406
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 702
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,545
Annual Return 2007 rr_AnnualReturn2007 6.12%
Annual Return 2008 rr_AnnualReturn2008 (20.81%)
Annual Return 2009 rr_AnnualReturn2009 28.61%
Annual Return 2010 rr_AnnualReturn2010 24.00%
Annual Return 2011 rr_AnnualReturn2011 (3.54%)
Annual Return 2012 rr_AnnualReturn2012 15.18%
Annual Return 2013 rr_AnnualReturn2013 39.43%
Annual Return 2014 rr_AnnualReturn2014 9.04%
Annual Return 2015 rr_AnnualReturn2015 (0.05%)
Annual Return 2016 rr_AnnualReturn2016 20.53%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarterly Return: Third Quarter 2009, 18.63%
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 18.63%
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarterly Return: Third Quarter 2011, -19.51%
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (19.51%)
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Past 1 Year rr_AverageAnnualReturnYear01 20.53%
Past 5 Years rr_AverageAnnualReturnYear05 16.10%
Past 10 Years rr_AverageAnnualReturnYear10 10.55%
(Vaughan Nelson Small Cap Value Fund) | Class Y | Return After Taxes on Distributions  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 18.43%
Past 5 Years rr_AverageAnnualReturnYear05 12.72%
Past 10 Years rr_AverageAnnualReturnYear10 8.10%
(Vaughan Nelson Small Cap Value Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares  
Prospectus: rr_ProspectusTable  
Past 1 Year rr_AverageAnnualReturnYear01 13.22%
Past 5 Years rr_AverageAnnualReturnYear05 12.32%
Past 10 Years rr_AverageAnnualReturnYear10 8.14%
[1] 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.
[2] The expense information shown in the table above may differ from the expense information disclosed in the Fund's financial highlights table because the financial highlights table reflects the operating expenses of the Fund and does not include acquired fund fees and expenses.
[3] NGAM 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.
[4] The Fund's investment 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's investment 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 the applicable expense limitations for Class A, C, N, T and Y shares. 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.
[5] Other expenses are estimated for the current fiscal year.
[6] Prior to the inception of Class Y shares (12/3/12), performance is that of Class A shares and reflects the higher net expenses of that share class.
[7] NGAM 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.
[8] Natixis Asset Management U.S., LLC ("Natixis AM US" 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 1.30%, 2.05%, 1.00%, 1.30% and 1.05% 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, 2018 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 the applicable expense limitation for Class A, C, N, T and Y shares. 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.
[9] The Fund's investment adviser has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.45%, 2.20%, 1.15%, 1.45% and 1.20% 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's investment 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 the applicable expense limitations for Class A, C, N, T and Y shares. 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] The expense information in the table above includes fee/expense recovery of less than 0.01%.
[11] The Fund's investment adviser has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.25%, 2.00%, 0.95%, 1.25% and 1.00% 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's investment 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 the applicable expense limitations for Class A, C, N, T and Y shares. 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.
[12] Other expenses are estimated for the current fiscal year.
[13] The expense information shown in the table above differs from the expense information disclosed in the Fund's financial highlights table because the financial highlights table reflects the operating expenses of the Fund and does not include acquired fund fees and expenses.
[14] The Fund's investment adviser has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.45%, 2.20%,1.15%, 1.45% and 1.20% 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, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's investment 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 the applicable expense limitations for Class A, C, N, T and Y shares. 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.