497

Natixis Funds Trust II

Exhibit Index

Exhibit	Exhibit Description
EX-101.INS	XBRL Instance Document
EX-101.SCH	XBRL Taxonomy Extension Schema Document
EX-101.CAL	XBRL Taxonomy Extension Calculation Linkbase
EX-101.DEF	XBRL Taxonomy Extension Definition Linkbase
EX-101.LAB	XBRL Taxonomy Extension Labels Linkbase
EX-101.PRE	XBRL Taxonomy Extension Presentation Linkbase

XML

Label	Element	Value
Prospectus:	rr_ProspectusTable
Document Type	dei_DocumentType	497
Document Period End Date	dei_DocumentPeriodEndDate	Jun. 30, 2017
Registrant Name	dei_EntityRegistrantName	Natixis Funds Trust II
Central Index Key	dei_EntityCentralIndexKey	0000052136
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Jun. 30, 2017
Document Effective Date	dei_DocumentEffectiveDate	Jun. 30, 2017
Prospectus Date	rr_ProspectusDate	Jul. 01, 2017

XML

(Loomis Sayles Dividend Income Fund)

Investment Goal

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

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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Loomis Sayles Dividend Income Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Loomis Sayles Dividend Income Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		0.60%	0.60%	0.60%		0.60%		0.60%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.66%	0.66%	0.58%	[1]	0.66%	[1]	0.66%
Total annual fund operating expenses		1.51%	2.26%	1.18%		1.51%		1.26%
Fee waiver and/or expense reimbursement	[2],[3]	0.41%	0.41%	0.38%		0.41%		0.41%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.10%	1.85%	0.80%		1.10%		0.85%

Example

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 for the first year 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:

If shares are redeemed:

Expense Example - (Loomis Sayles Dividend Income Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	681	987	1,315	2,240
Class C	288	667	1,173	2,563
Class N	82	337	612	1,398
Class T	359	676	1,015	1,972
Class Y	87	359	652	1,486

If shares are not redeemed:

Expense Example, No Redemption - (Loomis Sayles Dividend Income Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	188	667	1,173	2,563

Portfolio Turnover

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 35% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its assets in dividend-paying equity securities. Equity securities purchased by the Fund may include common stocks, preferred stocks, warrants, interests in real estate investment trusts ("REITs") and securities convertible into common or preferred stocks. A significant majority of the equity securities purchased by the Fund will be traded on a U.S. exchange and denominated in U.S. dollars. The Fund's non-U.S. equity investments, which will consist generally of American Depositary Receipts, but may include direct foreign investments as well, will be limited to 20% of the Fund's assets. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in U.S. equity indices published by S&P Global Ratings or Russell Investments. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

In deciding which securities to buy and sell, the Adviser seeks to identify companies that it believes are, among other things, attractively valued based on the Adviser's estimate of intrinsic value and have a strong track-record and/or potential for high dividend yield. The Adviser generally emphasizes high dividend yielding securities, but also attempts to balance risk and return and assess the future dividend paying ability of the issuers of such securities. The Adviser expects that the Fund's yield, which reflects the level of dividends paid by the Fund, will exceed the yield of the S&P 500® Index under normal market conditions. The Adviser generally seeks to find value by selecting individual stocks that it believes are attractive, rather than by attempting to achieve investment growth by rotating the Fund's holdings among various sectors of the economy.

The Fund may also purchase and sell (write) options for hedging and investment purposes and invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Investment Risks

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.

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 over-the-counter ("OTC") derivative transactions, such as OTC options. 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.

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 securities or other instruments denominated in, or that generate income denominated in, foreign currencies.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. 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. The Fund's focus on dividend-paying equity securities could cause the Fund to underperform the broader equity market if such securities are out of favor and a sharp rise in interest rates or an economic downturn could cause companies to reduce or eliminate their dividends. 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. Rule 144A securities may be less liquid than other equity securities.

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.

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.

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by comparing the Fund's one-year and life-of-fund performance with two broad measures 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.

Total Returns for Class A Shares

Highest Quarterly Return:
First Quarter 2013,11.13%

Lowest Quarterly Return:
Third Quarter 2015,-7.66%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Loomis Sayles Dividend Income Fund)	Past 1 Year	Life of Fund	Inception Date
Class A	7.67%	9.96%	Mar. 30, 2012
Class A | Return After Taxes on Distributions	6.90%	7.47%	Mar. 30, 2012
Class A | Return After Taxes on Distributions and Sale of Fund Shares	4.89%	7.33%	Mar. 30, 2012
Class C	12.26%	10.50%	Mar. 30, 2012
Class T	11.38%	10.74%	Mar. 30, 2012
Class Y	14.46%	11.60%	Mar. 30, 2012
S&P 500® Index	11.96%	12.64%	Mar. 30, 2012
Russell 1000® Value Index	17.34%	13.10%	Mar. 30, 2012

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.

The Fund revised its investment strategies on October 15, 2014 and July 18, 2016; performance may have been different had the current investment strategies been in place for all periods shown.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

(Loomis Sayles Global Growth Fund)

Investment Goal

The Fund's investment goal is long-term growth of capital.

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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Loomis Sayles Global Growth Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Loomis Sayles Global Growth Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		0.80%	0.80%	0.80%		0.80%		0.80%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		1.69%	1.38%	1.71%	[1]	1.69%	[1]	1.75%
Total annual fund operating expenses		2.74%	3.18%	2.51%		2.74%		2.55%
Fee waiver and/or expense reimbursement	[2],[3]	1.44%	1.13%	1.51%		1.44%		1.50%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.30%	2.05%	1.00%		1.30%		1.05%

Example

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 for the first year 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:

If shares are redeemed:

Expense Example - (Loomis Sayles Global Growth Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	700	1,247	1,820	3,369
Class C	308	874	1,566	3,407
Class N	102	637	1,199	2,731
Class T	379	945	1,538	3,141
Class Y	107	650	1,220	2,772

If shares are not redeemed:

Expense Example, No Redemption - (Loomis Sayles Global Growth Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	208	874	1,566	3,407

Portfolio Turnover

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 12% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks and depositary receipts. The Fund will invest in securities that provide exposure to no fewer than three countries, which will include the U.S. In addition, the Fund will invest at least 40% of its assets in securities of companies that maintain their principal place of business or conduct their principal business activities outside the U.S., companies that have their securities traded on non-U.S. exchanges or companies that have been formed under the laws of non-U.S. countries. Notwithstanding the foregoing, the Adviser does not consider a security to be foreign if it is included in the U.S. equity indices published by S&P Global Ratings or Russell Investments or if the security's country of risk defined by Bloomberg is the United States. The Fund may also invest up to 30% of its assets in emerging markets securities. The Fund considers a security to be an emerging markets security if its country of risk as defined by Bloomberg is included within the MSCI Emerging & Frontier Markets Index. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

The Fund normally invests across a wide range of sectors and industries. The Fund's portfolio manager employs a growth style of equity management, which means that the Fund seeks to invest in companies with sustainable competitive advantages, long-term structural growth drivers, attractive cash flow returns on invested capital, and management teams focused on creating long-term value for shareholders. The Fund's portfolio manager also aims to invest in companies when they trade at a significant discount to the estimate of intrinsic value.

The Fund will consider selling a portfolio investment when the portfolio manager believes an unfavorable structural change occurs within a given business or the markets in which it operates, a critical underlying investment assumption is flawed, when a more attractive reward-to-risk opportunity becomes available, when the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate.

The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Under normal market conditions, the Adviser does not intend to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Investment Risks

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.

Credit/Counterparty Risk: Credit/counterparty risk is the risk that 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 derivatives 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 over-the-counter ("OTC") derivatives transactions, such as foreign currency transactions. As a result, in instances when the Fund enters into OTC derivatives transactions, the Fund will be subject to the risk that its direct counterparties will not perform their obligations under the transactions and that the Fund will sustain losses or be unable to realize gains.

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 foreign currency forwards and foreign currency futures and invests in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. Under normal market conditions the Fund does not intend to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including foreign currency forwards, foreign currency futures and options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives, such as 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.

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. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser's assessment of the prospects for a company's growth is wrong, or if the Adviser's judgment of how other investors will value the company's growth is wrong, then the price of the company's stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock. Rule 144A securities may be less liquid than other equity securities. 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.

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.

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 the 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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Liquidity issues may also make it difficult to value the Fund's investments.

Management Risk: A strategy used by the Fund's portfolio manager 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.

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/Return Bar Chart and Table

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.

(Loomis Sayles Senior Floating Rate and Fixed Income Fund)

Investment Goal

The Fund seeks to provide a high level of current income.

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 $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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Loomis Sayles Senior Floating Rate and Fixed Income Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	3.50%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Loomis Sayles Senior Floating Rate and Fixed Income Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		0.60%	0.60%	0.60%		0.60%		0.60%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.28%	0.28%	0.21%	[1]	0.28%	[1]	0.28%
Total annual fund operating expenses		1.13%	1.88%	0.81%		1.13%		0.88%
Fee waiver and/or expense reimbursement	[2],[3]	0.08%	0.08%	0.06%		0.08%		0.08%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.05%	1.80%	0.75%		1.05%		0.80%

Example

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 for the first year 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:

If shares are redeemed:

Expense Example - (Loomis Sayles Senior Floating Rate and Fixed Income Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	453	689	943	1,670
Class C	283	583	1,009	2,194
Class N	77	253	444	996
Class T	354	592	849	1,583
Class Y	82	273	480	1,077

If shares are not redeemed:

Expense Example, No Redemption - (Loomis Sayles Senior Floating Rate and Fixed Income Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	183	583	1,009	2,194

Portfolio Turnover

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 75% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in a combination of adjustable floating rate loans and other floating rate debt instruments issued by U.S. and non-U.S. corporations or other business entities and fixed-income securities, including derivatives that reference the returns of these instruments.

Under normal market conditions, the Fund will invest at least 65% of its net assets (plus any borrowings made for investment purposes) in floating rate loans that either hold a senior position in the capital structure of the borrower, hold an equal ranking with other senior debt, or have characteristics (such as a senior position secured by liens with other senior debt) that the Adviser believes justify treatment as senior debt ("Senior Loans"). The Fund may invest in Senior Loans directly as an original lender or by assignment from a lender, or it may invest indirectly through participation agreements, interests in collateralized loan obligations ("CLOs") and derivatives that reference such instruments. Derivatives that reference the returns of Senior Loans may pay returns at fixed rather than variable rates. The Fund's investments may also include, but are not limited to, subordinated loans, below investment grade corporate bonds and investment grade fixed-income debt securities. The fixed-income securities in which the Fund may invest include preferred stocks. The Fund may invest in pay-in-kind ("PIK") securities and zero-coupon securities. The Fund may receive debt, equity or other securities or instruments as a result of the general restructuring of the debt of an issuer, the restructuring of a floating rate loan or as part of a package of securities acquired with a loan.

The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its net assets (plus any borrowings made for investment purposes) in other foreign securities, including up to 10% of its net assets (plus any borrowings made for investment purposes) in emerging market securities. Although certain securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if the issuer is included in the U.S. fixed-income indices published by Bloomberg Barclays.

Floating rate loans are debt obligations that have interest rates that adjust or "float" periodically (normally on a monthly or quarterly basis) based on a generally recognized base rate, such as the London Inter-Bank Offered Rate ("LIBOR") or the prime rate offered by one or more major U.S. banks. Floating rate loans are generally unrated or rated less than investment grade and may be subject to restrictions on resale. The Fund may invest without limit in securities of any rating, including those that are in default. The Fund has no requirements as to the range of maturities of the debt instruments in which it can invest or as to the market capitalization of the issuers of those instruments.

The Fund can borrow up to one-third of the Fund's assets (including the amount borrowed) and use other techniques to purchase investments, to manage its cash flow or to redeem shares, a technique referred to as "leverage." The Fund may also use derivative instruments, including, but not limited to, futures contracts, forward contracts, swaps (including, among others, credit default swaps, credit default swap indices, loan-only credit default swaps and loan-only credit default swap indices) and structured notes to try to increase the Fund's leverage, to enhance income, to hedge against fluctuations in interest rates or currency exchange rates, and/or as a substitute for the purchase or sale of securities.

The Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"), convertible securities, exchange-traded funds ("ETFs"), and mortgage-related securities, including adjustable rate mortgage securities and collateralized mortgage obligations, asset-backed securities, and U.S. government securities (including its agencies, instrumentalities and sponsored entities). The Fund may also engage in currency-related transactions. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

When deciding which securities to buy and sell, the Adviser will consider credit quality and whether credit quality is improving or declining, as well as return potential, in the context of market and economic risks. In addition to security selection, the Adviser expects to use cycle evaluation in conjunction with sector rotation in an effort to enhance or offset cyclical influences.

The Fund is "non-diversified." As a non-diversified fund, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers, as compared with other mutual funds that are diversified.

The Fund expects to 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 return, 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.

With the exception of the 80% test described above, the percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In addition, when calculating these exposures, the Fund may use the notional value or an adjusted notional value of a derivative to reflect what the Adviser believes to be the most accurate assessment of the Fund's real economic exposure.

Principal Investment Risks

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Borrowing and Leverage Risk: Borrowing and other investment techniques that utilize leverage, including use of derivatives, will increase the Fund's exposure to fluctuations in the prices of its assets and, therefore, the volatility of its share price. This magnifies the potential for gain and the risk of loss. Leverage may also cause the Fund to liquidate positions at unfavorable times or prices. The costs of leverage, such as interest on borrowed funds, will increase the Fund's expenses.

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. In the event of bankruptcy of a borrower, the Fund could experience delays or limitations with respect to its ability to realize the benefits of the collateral securing a Senior Loan. Senior Loans and other floating rate securities that are rated below investment-grade are considered predominantly speculative with respect to the ability of the issuer to make timely principal and interest payments. The value of loans made to such borrowers is likely to be more sensitive to adverse news about the borrower, markets or economy. The amount of public information available with respect to Senior Loans may be less extensive than that available for registered or exchange-listed securities. The Fund will also be subject to credit risk with respect to the counterparties of its derivatives transactions.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures contracts, forward contracts, swaps and structured notes) 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 over-the-counter ("OTC") derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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.

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.

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. Senior Loans typically have adjustable interest rates. As a result, it is expected that the values of Senior Loans held by the Fund will fluctuate less in response to interest rate changes than will fixed-rate debt securities; however, the interest rates paid by these loans will generally decrease if interest rates fall. Senior Loans and other fixed-income securities are subject to the risk that borrowers pay off the debts sooner than expected, possibly requiring the Fund to re-invest in lower-yielding securities. The value of zero-coupon and pay-in-kind bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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

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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. 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.

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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Senior Loans Risk: The risks associated with Senior Loans are similar to the risks of investing in below investment-grade securities. The Senior Loans in which the Fund expects to invest will generally not be rated investment grade by the rating agencies. Economic downturns generally lead to higher non-payment rates and a Senior Loan could lose a substantial part of its value prior to default. Senior Loans are subject to credit risk, and secured Senior Loans may not be adequately collateralized. The interest rates of Senior Loans reset frequently, and thus Senior Loans are subject to interest rate risk. Senior Loans are generally less liquid than many other debt securities and there may also be less public information available about Senior Loans as compared to other debt securities. Senior Loans may be difficult to value and may be subject to restrictions on resale, irregular trading activity, wide bid/ask spreads and extended trade settlement periods. Transactions in Senior Loans may take significantly longer than seven days to settle and, as a result, proceeds related to the sale of Senior Loans may not be readily available to make additional investments or to meet the Fund's redemption obligations. In order to satisfy redemption requests pending settlement of Senior Loans, the Fund may take a variety of measures, including, without limitation drawing on its cash and other short term positions and borrowing from banks (including under the Fund's line of credit), all of which may adversely affect the Fund's performance. With limited exceptions, the Adviser will take steps intended to ensure that it does not receive material non-public information about the issuers of Senior Loans who also issue publicly traded securities, and therefore the Adviser may have less information than other investors about certain of the Senior Loans in which it seeks to invest. Investing in Senior Loan participations exposes the Fund to the credit of the counterparty issuing the participation in addition to the credit of the ultimate borrower.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by comparing the Fund's one-year, five-year and life-of-fund performance with 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.

Total Returns for Class A Shares

Highest Quarterly Return:
First Quarter 2012, 5.05%

Lowest Quarterly Return:
Fourth Quarter 2015, -3.02%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Loomis Sayles Senior Floating Rate and Fixed Income Fund)	Past 1 Year	Past 5 Years	Life of Fund	Inception Date
Class A	7.29%	5.11%	5.64%	Sep. 30, 2011
Class A | Return After Taxes on Distributions	4.62%	2.57%	3.10%	Sep. 30, 2011
Class A | Return After Taxes on Distributions and Sale of Fund Shares	4.04%	2.79%	3.21%	Sep. 30, 2011
Class C	9.34%	5.08%	5.57%	Sep. 30, 2011
Class T	8.39%	5.31%	5.86%	Sep. 30, 2011
Class Y	11.51%	6.12%	6.63%	Sep. 30, 2011
S&P / LSTA Leveraged Loan Index	10.16%	5.11%	5.44%	Sep. 30, 2011

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.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

(Vaughan Nelson Select Fund)

Investment Goal

The Fund seeks long-term capital appreciation.

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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Vaughan Nelson Select Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Vaughan Nelson Select Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		0.85%	0.85%	0.85%		0.85%		0.85%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.27%	0.27%	0.21%	[1]	0.27%	[1]	0.27%
Total annual fund operating expenses		1.37%	2.12%	1.06%		1.37%		1.12%
Fee waiver and/or expense reimbursement	[2],[3]	0.12%	0.12%	0.11%		0.12%		0.12%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.25%	2.00%	0.95%		1.25%		1.00%

Example

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:

If shares are redeemed:

Expense Example - (Vaughan Nelson Select Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	695	963	1,262	2,108
Class C	303	642	1,118	2,434
Class N	97	317	565	1,275
Class T	374	651	960	1,836
Class Y	102	334	595	1,343

If shares are not redeemed:

Expense Example, No Redemption - (Vaughan Nelson Select Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	203	642	1,118	2,434

Portfolio Turnover

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 64% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

The Fund, under normal market conditions, will invest primarily in equity securities, including common stocks, preferred stocks, limited partnership interests, interests in limited liability companies, real estate investment trusts ("REITs") or other trusts and similar securities. The Fund is non-diversified, which means that it may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers than a diversified fund. Typically, the Fund's portfolio will hold 20 to 40 securities. The Fund may invest in companies with any market capitalization, although, it will typically focus its investments in mid- to large- capitalization companies. When opportunities present themselves, the Fund may establish short positions in specific equity securities or indices. While the Fund typically invests in equity securities, it may also invest in debt securities, including below investment grade fixed-income securities (commonly known as "junk bonds"). A fixed-income security is considered below investment grade quality when none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their top four ratings categories.

Vaughan Nelson invests in companies of all market capitalizations 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 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:

• Vaughan Nelson employs a value-driven investment philosophy that selects securities 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 the entire U.S. exchange-traded equity investment universe. Vaughan Nelson then narrows the investment universe by using fundamental analysis to construct a portfolio of 20 to 40 securities.

• Vaughan Nelson uses fundamental analysis to construct a portfolio 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 also employ its value driven investment philosophy to identify out-of-favor or misunderstood debt securities.

• 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 also may:

• Invest in convertible preferred stock and convertible debt securities.

• Invest in publicly traded master limited partnerships.

• Invest in foreign securities, including emerging market securities, traded in U.S. markets directly or through depositary receipt programs such as American Depositary Receipts ("ADRs") and Global Depositary Receipts ("GDRs").

• Invest in REITs.

• 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 derivative securities, such as options, for hedging and investment purposes.

Principal Investment Risks

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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 derivatives 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 over-the-counter ("OTC") derivatives transactions, such as foreign currency transactions. As a result, in instances when the Fund enters into OTC derivatives 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) 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 OTC derivatives, the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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.

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. 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 market 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. Taking short positions in stocks also results in a form of 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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. 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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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.

Short Sale Risk: Short sales can increase the volatility of the Fund and may lower the Fund's return or result in losses, which potentially may be unlimited. If the Fund is unable to borrow securities in connection with a short sale at an advantageous time or price, the Fund may be limited in its ability to pursue its short sale strategy or may incur losses. The use of short sales also exposes the Fund to leverage risk.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by comparing the Fund's one-year and life-of-fund performance with 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.

Total Returns for Class A Shares

Highest Quarterly Return:
First Quarter 2013,12.67%

Lowest Quarterly Return:
Third Quarter 2015,-6.28%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Vaughan Nelson Select Fund)	Past 1 Year	Life of Fund	Inception Date
Class A	0.58%	12.94%	Jun. 29, 2012
Class A | Return After Taxes on Distributions	0.20%	11.38%	Jun. 29, 2012
Class A | Return After Taxes on Distributions and Sale of Fund Shares	0.66%	9.71%	Jun. 29, 2012
Class C	4.93%	13.59%	Jun. 29, 2012
Class T	4.05%	13.78%	Jun. 29, 2012
Class Y	6.94%	14.73%	Jun. 29, 2012
S&P 500® Index	11.96%	14.09%	Jun. 29, 2012

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.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.10%, 1.85%, 0.80%, 1.10% and 0.85% 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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's 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 fee/expense was waived/reimbursed.

[3] NGAM Advisors, L.P. ("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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.30%, 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 March 31, 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 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.

[3] NGAM Advisors, L.P. ("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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.05%, 1.80%, 0.75%, 1.05% and 0.80% 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 March 31, 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 limitations for Class A, C, N, T and Y shares. The Fund will not be obligated to repay any such waived/reimbursed fees or expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

[3] NGAM Advisors, L.P. ("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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] NGAM Advisors, L.P. ("NGAM Advisors") 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, dividend expenses on securities sold short, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through March 31, 2019 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.

[3] NGAM Advisors, L.P. ("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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

XML

(ASG Dynamic Allocation Fund)

Investment Goal

The Fund seeks long-term capital appreciation. The secondary goal of the Fund is the protection of capital during unfavorable market conditions.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (ASG Dynamic Allocation Fund) - USD ($)	Class A		Class C	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none
Redemption fees	none		none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (ASG Dynamic Allocation Fund)		Class A	Class C	Class T		Class Y
Management fees		0.70%	0.70%	0.70%		0.70%
Distribution and/or service (12b-1) fees		0.25%	1.00%	0.25%		none
Other expenses		0.85%	0.81%	0.85%	[1]	0.84%
Acquired fund fees and expenses	[2]	0.06%	0.06%	0.06%		0.06%
Total annual fund operating expenses		1.86%	2.57%	1.86%		1.60%
Fee waiver and/or expense reimbursement	[3]	0.63%	0.60%	0.63%		0.63%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.23%	1.97%	1.23%		0.97%

Example

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:

If shares are redeemed:

Expense Example - (ASG Dynamic Allocation Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	693	1,068	1,468	2,581
Class C	300	743	1,312	2,860
Class T	372	755	1,169	2,321
Class Y	99	443	811	1,847

If shares are not redeemed:

Expense Example, No Redemption - (ASG Dynamic Allocation Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	200	743	1,312	2,860

Portfolio Turnover

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 115% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

The Fund tactically allocates its investments across a range of asset classes and global markets. Under normal market conditions, the Adviser will typically use a variety of derivative instruments, including equity, fixed-income and currency futures contracts and currency forward contracts, as well as exchange-traded funds ("ETFs") and money market and other short-term, high-quality securities, to achieve exposures to the following asset classes: (i) U.S. equity securities; (ii) foreign developed market equity securities; (iii) emerging market equity and fixed-income securities; (iv) U.S. fixed-income securities; and (v) foreign developed market fixed-income securities. 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 will typically obtain its target allocations through the use of long positions in futures and/or forward contracts, as well as investments in ETFs, which can provide exposure to certain asset classes that may not be readily available via futures contracts (e.g., domestic and international corporate bonds). The Fund may also hold short positions through the use of derivatives for hedging purposes. The Fund may obtain exposure to below investment grade fixed-income securities, also known as "junk bonds," through its investments in ETFs. Below investment grade fixed-income securities are rated below investment grade quality (i.e., none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their respective top four ratings categories).

In deciding which investments to buy and sell, the Adviser uses a quantitative systematic approach which analyzes multiple time periods. The approach consists of overweighting and/or underweighting allocations to asset classes based on a number of factors, including momentum signals, changes in hedge fund positioning, and/or market volatility. For example, the Adviser may overweight an asset class that demonstrates increasing momentum and/or hedge fund exposure relative to other asset classes. In estimating changes in hedge fund positioning, the Adviser may use various approaches, including an analysis of the returns of hedge funds included in one or more commercially available databases selected by the Adviser (for example, the Lipper TASS hedge fund database). When determining allocations to asset classes, the Adviser will also take into consideration correlations between assets and the volatilities of these assets. The minimum exposure to each asset class may be as low as 0% of total assets.

The Adviser separately manages the Fund's investments in derivatives and ETFs (the "Dynamic Allocation Portion") and the Fund's investments in money market and other short-term, high-quality securities (the "Money Market Portion," described further below). The Dynamic Allocation Portion will obtain economic leverage through the use of derivative instruments. Leverage can vary over time based on market conditions and the net notional value of the Dynamic Allocation Portion's investment exposure will not exceed 200% of the Fund's total assets. The Fund's total investment exposure may be greater than 200% of the Fund's total assets because it includes exposures obtained through both the Dynamic Allocation Portion and the Money Market Portion. Because the Fund's investment exposure will often exceed its total assets, it will be subject to increased risk compared to funds that do not leverage their investment exposure. While this increased investment exposure may magnify the Fund's potential for gains, it will also magnify the potential for losses. For these reasons, the Fund is intended for long-term investors.

The Adviser will seek to manage the annualized volatility (a statistical measure of the variation of returns) of the Fund's overall portfolio as part of the investment approach. The Adviser will monitor the portfolio daily, and will generally seek an annualized volatility level of no greater than 20% (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may significantly exceed 20% for various reasons, including changes in market levels of volatility and investments in instruments that are inherently volatile. This would increase the risk of investing in the Fund.

The Fund expects that, under normal market conditions, it will invest at least 40% of its total assets in the Money Market Portion. The Fund may invest less than this percentage in the Money Market Portion and the Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to provide collateral for the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value. The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit, repurchase agreements and time deposits) of issuers in that industry.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities; (ii) securities issued by foreign governments, their political subdivisions, agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

The Fund expects to add commodities as an available asset class for investment at a future date. Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives by investing in a wholly-owned subsidiary expected to be organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). The Fund anticipates registering the Commodity Subsidiary upon the attainment of approximately $100 million in assets under management. The maximum exposure to commodities will be 20% of total assets.

The Fund is non-diversified, which means that it may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Because the Fund may invest in the securities of a limited number of issuers, an investment in the Fund may involve a higher degree of risk than would be present in a diversified portfolio.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders.

Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time.

Principal Investment Risks

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: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary will not be registered under the Investment Company Act of 1940 (the "1940 Act") and will not be subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund is organized and the Commodity Subsidiary is expected to be organized, respectively, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to commodities markets, 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative or the underlying assets decrease in value over time.

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. 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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including ETFs, in which it invests in addition to its own expenses. In addition, investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial loss.

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. The Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing the Fund's performance in the first full year and by showing how the Fund's average annual returns for the one-year and Life-of-Fund periods compare to those of two broad measures of market performance. The Blended Index is an unmanaged, blended index composed of the following weights: 60% MSCI World Index (Net) and 40% Bloomberg Barclays U.S. Aggregate Bond Index. The two indices composing the Blended Index measure, respectively, the performance of global equity securities and global sovereign fixed-income securities. 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Third Quarter 2016, 1.83%

Lowest Quarterly Return:
First Quarter 2016, -0.41%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (ASG Dynamic Allocation Fund)	Past 1 Year	Life of Fund / Life of Class	Inception Date
Class Y	2.57%	1.17%	Nov. 30, 2015
Class Y | Return After Taxes on Distributions	2.42%	0.98%	Nov. 30, 2015
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	1.45%	0.81%	Nov. 30, 2015
Class A	(3.46%)	(4.35%)	Nov. 30, 2015
Class C	0.63%	0.21%	Nov. 30, 2015
Class T	(0.12%)	(1.35%)	Nov. 30, 2015
Morningstar Global Allocation Index	7.00%	5.37%	Nov. 30, 2015
Blended Index	5.71%	4.09%	Nov. 30, 2015

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

(ASG Global Alternatives Fund)

Investment Goal

The Fund pursues an absolute return strategy that seeks to provide capital appreciation consistent with the risk-return characteristics of a diversified portfolio of hedge funds. The secondary goal of the Fund is to achieve these returns with less volatility than major equity indices.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (ASG Global Alternatives Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (ASG Global Alternatives Fund)		Class A	Class C	Class N	Class T		Class Y
Management fees		1.14%	1.14%	1.14%	1.14%		1.14%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none	0.25%		none
Other expenses		0.18%	0.18%	0.10%	0.18%	[1]	0.18%
Total annual fund operating expenses	[2]	1.57%	2.32%	1.24%	1.57%		1.32%
Fee waiver and/or expense reimbursement	[3]	0.01%	0.01%	none	0.01%		0.01%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.56%	2.31%	1.24%	1.56%		1.31%

Example

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 examples for Class A, Class C, Class T and Class Y are 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:

If shares are redeemed:

Expense Example - (ASG Global Alternatives Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	725	1,040	1,379	2,333
Class C	334	723	1,239	2,654
Class N	126	393	681	1,500
Class T	405	732	1,082	2,069
Class Y	133	416	722	1,589

If shares are not redeemed:

Expense Example, No Redemption - (ASG Global Alternatives Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	234	723	1,239	2,654

Portfolio Turnover

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. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate.

Investments, Risks and Performance

Principal Investment Strategies

The Fund seeks to achieve long and short exposure to global equity, bond, currency and commodity markets through a wide range of derivative instruments and direct investments. Under normal market conditions, the Adviser typically will make extensive use of derivative instruments, in particular futures and forward contracts on global equity and fixed-income securities, securities indices (including both broad- and narrow-based securities indices), currencies, commodities and other instruments. These investments are intended to provide the Fund with risk and return characteristics similar to those of a diversified portfolio of hedge funds.

The Fund seeks to generate absolute returns over time rather than track the performance of any particular index of hedge fund returns. In selecting investments for the Fund, the Adviser uses quantitative models to estimate the market exposures that drive the aggregate returns of a diverse set of hedge funds. These market exposures may include, for example, exposures to the returns of stocks, fixed-income securities (including U.S. and non-U.S. government securities), currencies and commodities. In estimating these market exposures, the Adviser may use various approaches, including an analysis of the returns of hedge funds included in one or more commercially available databases selected by the Adviser (for example, the Lipper TASS hedge fund database), and seeks to use a variety of derivative instruments to capture such exposures in the aggregate while adding value through dynamic allocation among market exposures and volatility management. The Adviser will have great flexibility to allocate the Fund's derivatives exposure among various securities, indices, currencies, commodities and other instruments; the amount of the Fund's assets that may be allocated to derivative strategies and among these various instruments is expected to vary over time. When buying and selling securities and other instruments for the Fund, and in determining the amount of assets to be allocated to the Money Market Portion (as defined below), the Adviser also may consider other factors, such as: (i) the Fund's obligations under its various derivative positions; (ii) redemption requests; (iii) yield management; (iv) credit management; and (v) volatility management. The Fund will not invest directly in hedge funds. The Fund may invest in non-U.S. securities and instruments and securities and instruments traded outside the United States, and expects to engage in non-U.S. currency transactions.

The Adviser currently targets an annualized volatility level of 9% or less (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed its target volatility for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

Under normal market conditions, it is expected that no more than 25% of the Fund's total assets will be dedicated to initial and variation margin payments relating to the Fund's derivative transactions. The gross notional value of the Fund's derivative investments, however, will generally exceed 25% of the Fund's assets, and may significantly exceed the total value of the Fund's assets. The Fund expects that under normal market conditions it will invest at least 75% of its total assets in money market and other short-term, high-quality securities (the "Money Market Portion"), although the Fund may invest less than this percentage. The Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to finance the Fund's investments in derivatives and similar instruments and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities ("U.S. Government Obligations"); (ii) securities issued by foreign governments, their political subdivisions or agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks, and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives through a wholly-owned subsidiary organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). Under normal market conditions, no more than 10% of the Fund's total assets will be dedicated to initial and variation margin payments relating to these transactions.

The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit) of issuers in such industry. The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time.

Principal Investment Risks

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: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary is not registered under the Investment Company Act of 1940 (the "1940 Act") and is not subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund and the Commodity Subsidiary, respectively, are organized, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

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.

Hedge Fund Risk: Hedge funds are typically unregulated private investment pools available only to sophisticated investors. They are often illiquid and highly leveraged. Although the Fund will not invest directly in hedge funds, because the Fund's investments are intended to provide exposure to the factors that drive hedge fund returns, an investment in the Fund will be subject to many of the same risks associated with an investment in a diversified portfolio of hedge funds. Therefore, the Fund's performance may be lower than the returns of the broader stock market and the Fund's net asset value may fluctuate substantially over time.

Index/Tracking Error Risk: Although the Fund does not seek to track any particular index, the Fund seeks to analyze the factors that drive hedge fund returns, as determined by reference to one or more indices. These indices may not provide an accurate representation of hedge fund returns generally, and the Adviser's strategy may not successfully identify or be able to replicate factors that drive returns. There is a risk that hedge fund return data provided by third party hedge fund index providers may be inaccurate or may not accurately reflect hedge fund returns due to survivorship bias, self-reporting bias or other biases.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk/Return Bar Chart and Table

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, Life-of-Fund and Life-of-Class 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Third Quarter 2010, 7.23%

Lowest Quarterly Return:
First Quarter 2016, -8.36%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (ASG Global Alternatives Fund)	Past 1 Year	Past 5 Years	Life of Fund / Life of Class	Inception Date
Class Y	(4.23%)	3.14%	3.13%	Sep. 30, 2008
Class Y | Return After Taxes on Distributions	(4.23%)	1.99%	2.21%	Sep. 30, 2008
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	(2.39%)	2.11%	2.20%	Sep. 30, 2008
Class A	(9.89%)	1.68%	2.15%	Sep. 30, 2008
Class C	(6.09%)	2.11%	2.11%	Sep. 30, 2008
Class N	(4.05%)		1.32%	May 01, 2013
Class T	(6.79%)	2.38%	2.56%	Sep. 30, 2008
Barclay Fund of Funds Index	0.32%	3.27%	1.59%	Sep. 30, 2008
Barclay Fund of Funds Index (5/1/13)			2.05%	May 01, 2013

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

(ASG Managed Futures Strategy Fund)

Investment Goal

The Fund pursues an absolute return strategy that seeks to provide capital appreciation.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (ASG Managed Futures Strategy Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (ASG Managed Futures Strategy Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		1.24%	1.24%	1.24%		1.24%		1.24%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.26%	0.26%	0.15%	[1]	0.26%	[1]	0.26%
Total annual fund operating expenses		1.75%	2.50%	1.39%		1.75%		1.50%
Fee waiver and/or expense reimbursement	[2],[3]	0.01%	0.01%	none		0.01%		0.01%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.74%	2.49%	1.39%		1.74%		1.49%

Example

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:

If shares are redeemed:

Expense Example - (ASG Managed Futures Strategy Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	742	1,093	1,468	2,518
Class C	352	778	1,330	2,835
Class N	142	440	761	1,669
Class T	422	786	1,174	2,260
Class Y	152	473	818	1,790

If shares are not redeemed:

Expense Example, No Redemption - (ASG Managed Futures Strategy Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	252	778	1,330	2,835

Portfolio Turnover

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. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate.

Investments, Risks and Performance

Principal Investment Strategies

The Fund seeks to generate positive absolute returns over time. Under normal market conditions, the Adviser typically will make extensive use of a variety of derivative instruments, including futures and forward contracts, to capture the exposures suggested by its absolute return strategy while also seeking to add value through volatility management. These market exposures, which are expected to change over time, may include, for example, exposures to the returns of U.S. and non-U.S. equity and fixed-income securities indices (including both broad- and narrow-based securities indices), currencies and commodities. The Adviser will have great flexibility to allocate the Fund's derivatives exposure among various securities, indices, currencies, commodities and other instruments; the amount of the Fund's assets that may be allocated to derivative strategies and among these various instruments is expected to vary over time. The Adviser uses proprietary quantitative models to identify price trends in equity, fixed-income, currency and commodity instruments across time periods of various lengths. The Adviser believes that asset prices may show persistent trending behavior due to a number of behavioral biases among market participants as well as certain risk-management policies that will identify assets to purchase in upward-trending markets and identify assets to sell in downward-trending markets. The Adviser believes that following trends across a widely diversified set of assets, combined with active risk management, may allow it to earn a positive expected return over time. The Fund may have both "short" and "long" exposures within an asset class based upon the Adviser's analysis of multiple time horizons to identify trends in a particular asset class. A "short" exposure will benefit when the underlying asset class decreases in price. A "long" exposure will benefit when the underlying asset class increases in price. The Adviser will scale the notional exposure of the Fund's futures and currency forward positions with the objective of targeting a relatively stable level of annualized volatility for the Fund's overall portfolio. The Adviser currently targets an annualized volatility level of 17% or less (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed its target volatility for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

Under normal market conditions, it is expected that no more than 25% of the Fund's total assets will be dedicated to initial and variation margin payments relating to the Fund's derivative transactions. The gross notional value of the Fund's derivative investments, however, will generally exceed 25% of the Fund's total assets, and may significantly exceed the total value of the Fund's assets. The Fund expects that under normal market conditions it will invest at least 75% of its total assets in money market and other short-term, high-quality securities (such as bankers' acceptances, certificates of deposit, commercial paper, loan participations, repurchase agreements and time deposits) (the "Money Market Portion"), although the Fund may invest less than this percentage. The Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to support the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value. The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit, repurchase agreements and time deposits) of issuers in such industry.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities ("U.S. Government Obligations"); (ii) securities issued by foreign governments, their political subdivisions, agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives by investing in a wholly-owned subsidiary organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). Under normal market conditions, no more than 10% of the Fund's total assets will be dedicated to initial and variation margin payments relating to these transactions.

Although the Fund seeks positive absolute returns over time, it is likely that the Fund's investment returns may be volatile over short periods of time. The Fund may outperform the overall securities market during periods of flat or negative market performance and may underperform during periods of strong market performance. There can be no assurance that the Fund's returns over time or during any period will be positive or that the Fund will outperform the overall security markets over time or during any particular period.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time.

Principal Investment Risks

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: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary is not registered under the Investment Company Act of 1940 (the "1940 Act") and is not subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund and the Commodity Subsidiary, respectively, are organized, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

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 market 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. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year-to-year and by showing how the Fund's average annual returns for the one-year, five-year and Life-of-Fund periods compare to those of two broad measures 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
First Quarter 2015, 11.72%

Lowest Quarterly Return:
Second Quarter 2015, -10.57%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (ASG Managed Futures Strategy Fund)	Past 1 Year	Past 5 Years	Life of Fund / Life of Class	Inception Date
Class Y	(5.47%)	2.77%	4.26%	Jul. 30, 2010
Class Y | Return After Taxes on Distributions	(5.48%)	1.42%	2.70%	Jul. 30, 2010
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	(3.10%)	1.70%	2.82%	Jul. 30, 2010
Class A	(11.09%)	1.32%	3.07%	Jul. 30, 2010
Class C	(7.39%)	1.73%	3.22%	Jul. 30, 2010
Class T	(8.08%)	2.00%	3.61%	Jul. 30, 2010
Credit Suisse Managed Futures Liquid Index	4.19%	4.33%	3.59%	Jul. 30, 2010
SG Trend Index	(6.19%)	2.16%	2.64%	Jul. 30, 2010

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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

(ASG Tactical U.S. Market Fund)

Investment Goal

The Fund seeks long-term capital appreciation, with emphasis on the protection of capital during unfavorable market conditions.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (ASG Tactical U.S. Market Fund) - USD ($)	Class A		Class C	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none
Redemption fees	none		none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (ASG Tactical U.S. Market Fund)		Class A	Class C	Class T		Class Y
Management fees		0.80%	0.80%	0.80%		0.80%
Distribution and/or service (12b-1) fees		0.25%	1.00%	0.25%		none
Other expenses	[1]	0.35%	0.35%	0.35%	[2]	0.35%
Total annual fund operating expenses		1.40%	2.15%	1.40%		1.15%
Fee waiver and/or expense reimbursement	[3]	0.16%	0.16%	0.16%		0.16%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.24%	1.99%	1.24%		0.99%

Example

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:

If shares are redeemed:

Expense Example - (ASG Tactical U.S. Market Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	694	965	1,270	2,134
Class C	302	644	1,127	2,459
Class T	373	653	969	1,862
Class Y	101	336	604	1,371

If shares are not redeemed:

Expense Example, No Redemption - (ASG Tactical U.S. Market Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	202	644	1,127	2,459

Portfolio Turnover

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 42% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

The Fund pursues its investment goal primarily through investments in equity securities that broadly represent the U.S. equities market (including common stocks, preferred stocks and exchange-traded funds ("ETFs") related to equity investments); derivative instruments related to the U.S. equities market (primarily futures contracts on U.S. equity indices); and fixed-income securities (including money market and other short-term or variable-rate, high-quality securities and related ETFs). Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investments that are tied economically to the U.S. The Adviser considers an investment to be tied economically to the U.S. if the investment is included in an index representative of the U.S., the investment's returns are linked to the performance of such an index, or the investment is exposed to the economic risks and returns of the U.S. The Adviser may use quantitative models to determine when to magnify the Fund's exposure to the U.S. equity market, for example, through the purchase of futures contracts, or, alternatively, when to decrease such exposure, for example, through the sale of futures contracts or through the purchase of ETFs that it believes may effectively hedge equity investments. The Adviser may increase the Fund's exposure to the U.S. equity market to up to 130% of the Fund's total assets when it believes that the risk of loss is justified by potential returns. The Adviser may decrease such exposure to as little as 0% of the Fund's total assets, in an attempt to limit the effects of extreme market drawdowns, when it believes that the risk of loss is not offset by potential returns. Such increases and decreases may lag changes in the market, and there is no guarantee that the Adviser's models will accurately predict market movement. Because the Fund's equity market exposure will often exceed its total assets, it will be subject to increased risk compared to funds that do not leverage their equity market exposure. While this increased exposure to equity investments may magnify the Fund's potential for gains, it also may magnify the potential for loss. For these reasons, the Fund is intended for long-term investors.

Equity Securities Investments. The equity securities portion of the Fund is managed by NGAM Advisors, L.P. (through its division, Active Index Advisors®) ("NGAM Advisors"), with the exception of any investments in ETFs, which are selected by the Adviser. NGAM Advisors utilizes a proprietary sampling system when deciding which securities to purchase, with the goal of tracking the performance of the large-capitalization U.S. equity market. In an attempt to reduce adverse tax consequences, the portion of the Fund managed by NGAM Advisors may hold securities that are not considered to represent the large-capitalization U.S. equity market, or hold securities in amounts disproportionate to their weights within the large-capitalization U.S. equity market. The portfolio may experience tracking error and is not guaranteed to replicate exactly the large-capitalization U.S. equity market.

Derivative Investments. As discussed above, the Adviser seeks to complement the equity portion of the Fund with investments in derivative instruments intended to enhance return and, during times of significant market decline, mitigate losses. In addition, the Adviser uses futures contracts to manage volatility and adjusts the Fund's exposure to equity investments in times of significantly increased volatility (including, when volatility is more than double the long-term average volatility of the U.S. equity markets). As of March 31, 2017, the long-term average annualized volatility of the U.S. equity markets was 18.0%. The Fund's actual or realized volatility during certain periods or over time may materially exceed the long-term average annualized volatility of the U.S. equity markets, for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. The Fund may have both "short" and "long" exposures to equity investments simultaneously. The Fund will benefit from a "short" exposure when equity and equity-related investments decrease in price, and will benefit from a "long" exposure when equity and equity-related investments increase in price.

Fixed-Income Investments. The assets allocated to the fixed-income portion will be used primarily to support the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. The fixed-income portion of the Fund will only invest in high-quality securities that are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities; (ii) securities issued by foreign governments, their political subdivisions or agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic and foreign banks, including domestic or foreign branches or subsidiaries of such banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

When buying and selling securities and other instruments for the Fund, and when allocating assets to NGAM Advisors, the Adviser may consider: (i) the Adviser's proprietary quantitative models, including the outlook on volatility and market decline; (ii) the Fund's obligations under its various derivative positions; (iii) redemption requests; (iv) yield management; (v) credit management; and (vi) volatility management.

The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit) of issuers in such industry.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs that reduce Fund returns.

With the exception of the Fund's 80% policy, the percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In accordance with applicable requirements of the U.S. Securities and Exchange Commission (the "SEC"), the Fund will notify shareholders prior to any change to the 80% policy discussed above taking effect.

Principal Investment Risks

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.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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 futures contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures contracts, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

Index/Tracking Error Risk: This is the risk that, to the extent the Fund's principal investment strategies utilize indices, the Fund's performance may not track the performance of such indices. For example, the equity securities in which the Fund invests may not provide investment performance matching the performance of broad-based large capitalization U.S. equity indices. Similarly, changes in the value of the derivatives in which the Fund invests may not correlate perfectly with the underlying assets or indices associated with such derivatives. Moreover, the ETFs in which the Fund invests may not replicate the performance of the indices they track and may, therefore, result in loss to the Fund.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including ETFs, in which it invests in addition to its own expenses. In addition, investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk/Return Bar Chart and Table

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 and Life-of-Fund periods compare to those of two broad measures 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2014, 6.19%

Lowest Quarterly Return:
Third Quarter 2015, -6.50%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (ASG Tactical U.S. Market Fund)	Past 1 Year	Life of Fund / Life of Class	Inception Date
Class Y	4.41%	8.90%	Sep. 30, 2013
Class Y | Return After Taxes on Distributions	4.24%	7.91%	Sep. 30, 2013
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	2.65%	6.73%	Sep. 30, 2013
Class A	(1.93%)	6.65%	Sep. 30, 2013
Class C	2.39%	7.82%	Sep. 30, 2013
Class T	1.51%	7.76%	Sep. 30, 2013
S&P 500® Index	11.96%	11.53%	Sep. 30, 2013
Barclay Equity Long/Short Index	1.71%	3.64%	Sep. 30, 2013

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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.

(Loomis Sayles Strategic Alpha Fund)

Investment Goal

The Fund seeks to provide an attractive absolute total return, complemented by prudent investment management designed to manage risks and protect investor capital. The secondary goal of the Fund is to achieve these returns with relatively low volatility.

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 $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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Loomis Sayles Strategic Alpha Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.25%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Loomis Sayles Strategic Alpha Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees	[1]	0.60%	0.60%	0.60%		0.60%		0.60%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.15%	0.15%	0.08%	[2]	0.15%	[2]	0.15%
Total annual fund operating expenses	[3]	1.00%	1.75%	0.68%		1.00%		0.75%
Fee waiver and/or expense reimbursement	[4],[5]	none	none	none		none		none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.00%	1.75%	0.68%		1.00%		0.75%

Example

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:

If shares are redeemed:

Expense Example - (Loomis Sayles Strategic Alpha Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	523	730	954	1,598
Class C	278	551	949	2,062
Class N	69	218	379	847
Class T	349	560	789	1,444
Class Y	77	240	417	930

If shares are not redeemed:

Expense Example, No Redemption - (Loomis Sayles Strategic Alpha Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	178	551	949	2,062

Portfolio Turnover

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 72% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

The Fund has an absolute total return investment objective, which means that it is not managed relative to an index and that it attempts to achieve positive total returns over a full market cycle. The Fund intends to pursue its objective by utilizing a flexible investment approach that allocates investments across a global range of investment opportunities related to credit, currencies and interest rates, while employing risk management strategies to mitigate downside risk. The Fund may invest up to 100% of its total assets in below investment grade fixed-income securities (also known as "junk bonds") and derivatives that have returns related to the returns on below investment grade fixed-income securities, although it is expected that, under normal market conditions, the Fund's net exposure (i.e., long exposures obtained through direct investments in securities and in derivatives minus short exposures obtained through derivatives) to below investment grade fixed-income assets generally will not exceed 50% of the Fund's total assets. Below investment-grade fixed-income securities are rated below investment-grade quality (i.e., none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their respective top four ratings categories). Under normal market conditions, the Fund also may invest up to 50% of its total assets in investments denominated in non-U.S. currencies and related derivatives, including up to 20% in investments denominated in emerging market currencies and related derivatives. The Fund expects that its exposure to these asset classes will often be obtained substantially through the use of derivative instruments. The Fund defines an "emerging market currency" as a currency of a country that carries a sovereign debt quality rating that is rated below investment grade by either S&P or Moody's, or is unrated by both S&P and Moody's. Currency positions that are intended to hedge the Fund's non-U.S. currency exposure (i.e., currency positions that are not made for investment purposes) will offset positions in the same currency that are made for investment purposes when calculating the limitation on investments in non-U.S. and emerging market currency investments because the Fund believes that hedging a currency position is likely to negate some or all of the currency risk associated with the original currency position. The Fund does not have limits on the duration of its portfolio, and the Fund's duration will change over time. The Fund also may invest in preferred stocks.

In selecting investments for the Fund, the Adviser develops long-term portfolio themes driven by macro-economic indicators. These include global economic trends, demographic trends and labor supply, analysis of global capital flows and assessments of geopolitical factors. The Adviser then develops shorter-term portfolio strategies based on factors including, but not limited to, economic, credit and Federal Reserve cycles, and top-down sector valuations and bottom-up security valuations. The Adviser seeks to actively manage risk, with a focus on managing the Fund's exposure to credit, interest rate and currency risks in relation to the market. Additionally, the portfolio managers will use risk management tools, such as models that evaluate risk correlation to various market factors or asset classes, to seek to manage risk on an ongoing basis. 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 Adviser currently targets an annualized volatility range of 4% to 6% (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed or be lower than its target volatility range for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

The Fund will pursue its investment goal by obtaining long investment exposures through investments in securities and derivatives and short investment exposures substantially through derivatives. A "long" investment exposure is an investment that rises in value with a rise in the value of an asset, asset class or index and declines in value with a decline in the value of that asset, asset class or index. A "short" investment exposure is an investment that rises in value with a decline in the value of an asset, asset class or index and declines in value with a rise in the value of that asset, asset class or index. The value of the Fund's long and short investment exposures may, at times, each reach 100% of the assets invested in the Fund (excluding instruments primarily used for duration management or yield curve management and short-term investments (such as cash and money market instruments)), although these exposures may be higher or lower at any given time.

Fixed-Income Investments. In connection with its principal investment strategies, the Fund may invest in a broad range of U.S. and non-U.S. fixed-income securities, including, but not limited to, corporate bonds, municipal securities, U.S. and non-U.S. government securities (including their agencies, instrumentalities and sponsored entities), securities of supranational entities, emerging market securities, commercial and residential mortgage-backed securities, collateralized mortgage obligations, other mortgage-related securities (such as adjustable rate mortgage securities), asset-backed securities, bank loans, convertible bonds, securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"), real estate investment trusts ("REITs"), zero-coupon securities, step coupon securities, pay-in-kind ("PIK") securities, inflation-linked bonds, variable and floating rate securities, private placements and commercial paper.

Non-U.S. Currency Investments. Under normal market conditions, the Fund may engage in a broad range of transactions involving non-U.S. and emerging market currencies, including, but not limited to, purchasing and selling forward currency exchange contracts in non-U.S. or emerging market currencies, investing in non-U.S. currency futures contracts, investing in options on non-U.S. currencies and non-U.S. currency futures, investing in cross-currency instruments (such as swaps), investing directly in non-U.S. currencies and investing in securities denominated in non-U.S. currencies. The Fund may engage in non-U.S. currency transactions for investment or for hedging purposes.

Derivative Investments. For investment and hedging purposes, the Fund may invest substantially in a broad range of derivatives instruments and sometimes the majority of its investment returns will derive from its derivative investments. These derivative instruments include, but are not limited to, futures contracts (such as treasury futures and index futures), forward contracts, options (such as options on futures contracts, options on securities, interest rate/bond options, currency options, options on swaps and over-the-counter ("OTC") options), warrants (such as non-U.S. currency warrants) and swap transactions (such as interest rate swaps, total return swaps and index swaps). In addition, the Fund may invest in credit derivative products that may be used to manage default risk and credit exposure. Examples of such products include, but are not limited to, credit default swap index products (such as LCDX, CMBX and ABX index products), single name credit default swaps, loan credit default swaps and asset-backed credit default swaps. The Fund may, at times, invest substantially all of its assets in derivatives and securities used to support its obligations under those derivatives. The Fund's strategy may be highly dependent on the use of derivatives, and to the extent that they become unavailable or unattractive the Fund may be unable to fully implement its investment strategy.

Equity Investments. In connection with its principal investment strategies, the Fund may invest in preferred stocks and convertible preferred stocks. The Fund is non-diversified, which means it may invest a greater portion of its assets in a particular issuer and may invest in fewer issuers. Because the Fund may invest in the securities of fewer issuers, an investment in the Fund may involve a higher degree of risk than would be present in a diversified portfolio.

The Fund expects to 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In addition, when calculating these exposures, the Fund may use the market value, the notional value, an adjusted notional value or some other measure of the value of a derivative in order to reflect what the Adviser believes to be the most accurate assessment of the Fund's real economic exposure. The total notional value of the Fund's derivative instruments may significantly exceed the total value of the Fund's assets.

Although the Fund seeks positive total returns over time, the Fund's investment returns may be volatile over short periods of time. The Fund may outperform the overall securities market during periods of flat or negative performance and may underperform during periods of strong market performance. There can be no assurance that the Fund's returns over time or during any period will be positive.

Principal Investment Risks

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.

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

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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 over-the-counter ("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.

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 a significant portion of its assets in currency-related instruments and may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. The Advisor 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures contracts, forward contracts, options, warrants 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, such as futures, forward contracts, options, warrants, foreign currency transactions, swaps and credit default swaps, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts, swaps and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

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 preferred stocks could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock.

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.

Inflation/Deflation Risk: Inflation risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. Deflation risk is the risk that prices throughout the economy decline over time (the opposite of inflation). Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund's portfolio. Because the Fund seeks positive returns that exceed the rate of inflation over time, if the portfolio managers' inflation forecasts are incorrect, the Fund may be more severely impacted than other funds.

Interest Rate Risk: Interest rate risk is the risk that the value of the Fund's investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. The value of zero-coupon and PIK bonds may be more sensitive to fluctuations in interest rates than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in stocks also results in a form of 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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will 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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year-to-year and by showing how the Fund's average annual returns for the one-year, five-year and Life-of-Fund periods compare to those of two broad measures 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
First Quarter 2012, 5.54%

Lowest Quarterly Return:
Third Quarter 2011, -4.71%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Loomis Sayles Strategic Alpha Fund)	Past 1 Year	Past 5 Years	Life of Fund / Life of Class	Inception Date
Class Y	6.86%	4.23%	2.90%	Dec. 15, 2010
Class Y | Return After Taxes on Distributions	5.77%	2.96%	1.66%	Dec. 15, 2010
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	3.87%	2.72%	1.72%	Dec. 15, 2010
Class A	2.03%	3.06%	1.92%	Dec. 15, 2010
Class C	4.70%	3.17%	1.85%	Dec. 15, 2010
Class T	3.93%	3.43%	2.21%	Dec. 15, 2010
3-month London Interbank Offered Rate (LIBOR)	0.66%	0.38%	0.36%	Dec. 15, 2010
3-month LIBOR +300 basis points	3.73%	3.44%	3.42%	Dec. 15, 2010

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.

(McDonnell Intermediate Municipal Bond Fund)

Investment Goal

The Fund seeks a high level of federal tax-exempt current income, consistent with the preservation of capital.

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 $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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (McDonnell Intermediate Municipal Bond Fund) - USD ($)	Class A		Class C	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	3.00%		none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none
Redemption fees	none		none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (McDonnell Intermediate Municipal Bond Fund)		Class A	Class C	Class T		Class Y
Management fees		0.40%	0.40%	0.40%		0.40%
Distribution and/or service (12b-1) fees		0.25%	1.00%	0.25%		none
Other expenses		0.23%	0.23%	0.23%	[1]	0.23%
Total annual fund operating expenses		0.88%	1.63%	0.88%		0.63%
Fee waiver and/or expense reimbursement	[2]	0.18%	0.18%	0.18%		0.18%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.70%	1.45%	0.70%		0.45%

Example

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:

If shares are redeemed:

Expense Example - (McDonnell Intermediate Municipal Bond Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	369	555	756	1,336
Class C	248	497	870	1,918
Class T	320	505	707	1,290
Class Y	46	184	333	769

If shares are not redeemed:

Expense Example, No Redemption - (McDonnell Intermediate Municipal Bond Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	148	497	870	1,918

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund's performance. During its most recently ended fiscal year, the Fund's portfolio turnover rate was 48% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus borrowings made for investment purposes) in municipal securities that pay interest exempt from federal income taxes. Municipal securities are debt instruments typically issued by or on behalf of state and local governments, territories or possessions of the United States, including the District of Columbia, and their political subdivisions, agencies and instrumentalities and may include general obligation, revenue and private activity bonds and notes. In addition, the Fund may invest up to 20% of its assets in securities that pay interest subject to federal income taxation. The Fund may invest up to 20% of its assets in debt securities subject to the federal alternative minimum tax. The Fund's investments may include securities issued by the U.S. government, its agencies and instrumentalities and corporate debt securities. The Fund will invest primarily in investment grade fixed-income securities. "Investment grade" securities are those securities that are rated in one of the top four ratings categories at the time of purchase by at least one of the three major ratings agencies (Moody's Investors Service, Inc., Fitch Investors Services, Inc. or S&P Global Ratings), or, if unrated, are determined by McDonnell Investment Management, LLC ("McDonnell" or the "Subadviser") to be of comparable quality. The Subadviser considers pre-refunded bonds and municipal securities escrowed to maturity using U.S. Treasury securities or U.S. government agency securities to be investment grade securities, regardless of rating. The Fund may also invest up to 10% of its assets in securities that are not investment grade (commonly known as "junk bonds"). Under normal circumstances, the dollar-weighted average maturity of the Fund's portfolio is expected to be between 3 and 10 years although the Fund may invest in securities of any maturity.

The portfolio management team seeks to build a portfolio based on a number of factors including sector, duration and maturity distribution, yield, expected return, credit momentum outlook (sector and security level), credit quality, security structure, issue size and liquidity. Through the use of quantitative and fundamental analysis, the pool of possible portfolio investments is screened using these factors to arrive at a narrower universe of securities that the Subadviser believes are suitable for the Fund's portfolio. Potential investments are also subject to a portfolio risk assessment that may include the following:

• Determining the ability of creditors to fully repay debt obligations in a timely manner.

• Use of a wide variety of internal and external quantitative and analytical and informational sources to assess likelihood of repayment.

• Monitoring rating agency and third party surveillance sources with an emphasis on core holdings.

The Subadviser may sell a security for a variety of reasons, including duration management, yield curve positioning, sector rotation, a change in credit momentum outlook or if more attractive investment opportunities are identified.

The Fund may also:

• Invest in when-issued securities and securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities").

• Enter into futures transactions for hedging and investment purposes.

• Invest in other investment companies to the extent permitted by the Investment Company Act of 1940.

Principal Investment Risks

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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.

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, such as options, foreign currency transactions, futures transactions, and swap transactions, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for over-the-counter 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.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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

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. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. 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.

Municipal Securities Risk: Municipal bonds are investments issued by states, cities, public authorities or political subdivisions to raise money for public purposes, including general obligation bonds and revenue obligations. Municipal securities are subject to information risk, liquidity risk, credit risk and the risks that economic, political, fiscal or regulatory events, legislative changes and the enforceability of rights of municipal bond holders could adversely affect the values of municipal bonds. Municipal obligations may be susceptible to downgrades or defaults during recessions or similar periods of economic stress and insolvent municipalities may file for bankruptcy, which could significantly affect the rights of creditors and the value of the municipal securities. In addition, if the municipal securities held by the Fund fail to meet certain legal requirements allowing interest distributed from such securities to be tax-exempt, the interest received and distributed to shareholders by the Fund may be taxable.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year-to-year and by showing how the Fund's average annual returns for the one-year and Life-of-Fund periods compare to two broad measures 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2016, 2.21%

Lowest Quarterly Return:
Fourth Quarter 2016, -3.76%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (McDonnell Intermediate Municipal Bond Fund)		Past 1 Year	Life of Fund / Life of Class	Inception Date
Class Y		(0.55%)	1.48%	Dec. 31, 2012
Class Y | Return After Taxes on Distributions		(0.55%)	1.48%	Dec. 31, 2012
Class Y | Return After Taxes on Distributions and Sale of Fund Shares		0.33%	1.47%	Dec. 31, 2012
Class A		(3.75%)	0.40%	Dec. 31, 2012
Class C		(2.42%)	0.45%	Dec. 31, 2012
Class T		(3.29%)	0.54%	Dec. 31, 2012
Bloomberg Barclays Municipal Bond Index	[1]	0.25%	2.42%	Dec. 31, 2012
Bloomberg Barclays 3-15 Year Blend Municipal Bond Index		(0.05%)	2.14%	Dec. 31, 2012

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] 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.

[3] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.15%, 1.90%, 1.15% and 0.90% of the Fund's average daily net assets for Class A, Class C, Class T and Class Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational expenses 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%; the ratios 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] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.54%, 2.29%, 1.24%, 1.54% and 1.29% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class N, Class T and Class 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 fee/expense was waived/reimbursed.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.70%, 2.45%, 1.40%, 1.70% and 1.45% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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 1.70%, 2.45%, 1.40%, 1.70% and 1.45% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class Y shares, respectively. 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 fee/expense was waived/reimbursed.

[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.

[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.

[1] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%.

[2] Other expenses are estimated for the current fiscal year.

[3] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.24%, 1.99%, 1.24% and 0.99% of the Fund's average daily net assets for Class A, Class C, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[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.

[1] The Fund's operating expenses have been restated to reflect a reduction in management fees, effective as of July 1, 2017, as if such reduction had been in effect during the fiscal year ended December 31, 2016. The information has been restated to better reflect anticipated expenses of the Fund.

[2] Other expenses are estimated for the current fiscal year.

[3] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%.

[4] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.00%, 1.75%, 0.70%, 1.00% and 0.75% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class N, Class T and Class 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 fee/expense was waived/reimbursed.

[5] 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.

[1] A 0.75% contingent deferred sales charge ("CDSC") may apply to certain purchases of Class A shares of $500,000 or more that are redeemed within eighteen months of the date of purchase.

[1] Other expenses are estimated for the current fiscal year.

[2] 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 0.70%, 1.45%, 0.70% and 0.45% of the Fund's average daily net assets for Class A, Class C, Class T and Class 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[1] Effective May 22, 2017, the Bloomberg Barclays Municipal Bond Index replaced the Bloomberg Barclays 3-15 Year Blend Municipal Bond Index as the Fund's primary benchmark because the Fund believes the Bloomberg Barclays Municipal Bond Index, an index which covers the U.S. dollar-denominated long-term tax exempt bond market, is a more appropriate comparison to the Fund's investment strategies. It is not possible to invest directly in an index.

XML

(Natixis Oakmark Fund)

Investment Goal

The Fund seeks long-term capital appreciation.

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").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Natixis Oakmark Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Natixis Oakmark Fund)		Class A	Class C	Class N		Class T		Class Y
Management fees		0.69%	0.69%	0.69%		0.69%		0.69%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		0.25%		none
Other expenses		0.24%	0.24%	0.12%	[1]	0.24%	[1]	0.23%
Total annual fund operating expenses		1.18%	1.93%	0.81%		1.18%		0.92%
Fee waiver and/or expense reimbursement	[2],[3]	none	none	none		none		none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.18%	1.93%	0.81%		1.18%		0.92%

Example

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:

If shares are redeemed:

Expense Example - (Natixis Oakmark Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	688	928	1,187	1,924
Class C	296	606	1,042	2,254
Class N	83	259	450	1,002
Class T	367	615	883	1,646
Class Y	94	293	509	1,131

If shares are not redeemed:

Expense Example, No Redemption - (Natixis Oakmark Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	196	606	1,042	2,254

Portfolio Turnover

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 16% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund primarily invests in common stocks of U.S. companies. The Fund generally invests in securities of larger capitalization companies in any industry. Harris Associates L.P. ("Harris Associates") uses a value investment philosophy in selecting equity securities, including common stocks. This philosophy is based upon the belief that, over time, a company's stock price converges with 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 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' estimate of 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 60 stocks.

Principal Investment Risks

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.

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.

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.

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/Return Bar Chart and Table

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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2009, 24.26%

Lowest Quarterly Return:
Fourth Quarter 2008, -26.95%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Natixis Oakmark Fund)	Past 1 Year	Past 5 Years	Past 10 Years
Class Y	18.69%	15.34%	6.75%
Class Y | Return After Taxes on Distributions	17.56%	13.89%	6.00%
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	11.35%	12.19%	5.35%
Class A	11.55%	13.69%	5.81%
Class C	16.45%	14.19%	5.65%
Class T	15.43%	14.46%	6.18%
S&P 500® Index	11.96%	14.66%	6.95%

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.

(Vaughan Nelson Value Opportunity Fund)

Investment Goal

The Fund seeks long-term capital appreciation.

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").

Shareholder Fees

(fees paid directly from your investment)

Shareholder Fees - (Vaughan Nelson Value Opportunity Fund) - USD ($)	Class A		Class C	Class N	Class T	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%		none	none	2.50%	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	[1]	1.00%	none	none	none
Redemption fees	none		none	none	none	none

Annual Fund Operating Expenses

(expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - (Vaughan Nelson Value Opportunity Fund)		Class A	Class C	Class N	Class T		Class Y
Management fees		0.80%	0.80%	0.80%	0.80%		0.80%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none	0.25%		none
Other expenses		0.18%	0.18%	0.08%	0.18%	[1]	0.18%
Acquired fund fees and expenses	[2]	0.25%	0.25%	0.25%	0.25%		0.25%
Total annual fund operating expenses		1.48%	2.23%	1.13%	1.48%		1.23%
Fee waiver and/or expense reimbursement	[3]	none	none	none	none		none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.48%	2.23%	1.13%	1.48%		1.23%

Example

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:

If shares are redeemed:

Expense Example - (Vaughan Nelson Value Opportunity Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	717	1,016	1,336	2,242
Class C	326	697	1,195	2,565
Class N	115	359	622	1,375
Class T	397	706	1,038	1,974
Class Y	125	390	676	1,489

If shares are not redeemed:

Expense Example, No Redemption - (Vaughan Nelson Value Opportunity Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	226	697	1,195	2,565

Portfolio Turnover

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 57% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest primarily in companies that, at the time of purchase, have market capitalizations either within the capitalization range of the Russell Midcap® Value Index, an unmanaged index that measures the performance of companies with lower price-to-book ratios and lower forecasted growth values within the broader Russell Midcap® Index, or of $15 billion or less. While the market capitalization range for the Russell Midcap® Value Index fluctuates, at December 31, 2016, it was $454.2 million to $38.8 billion. However, the Fund does not have any market capitalization limits and may invest in companies with smaller or larger capitalizations. 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 similar securities.

Vaughan Nelson Investment Management, L.P. ("Vaughan Nelson") invests in medium-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:

• Vaughan Nelson employs a value-driven investment philosophy that selects stocks selling at a relatively low value based on business fundamentals, economic margin analysis and discounted cash flow models. Vaughan Nelson selects companies that it believes are out of favor or misunderstood.

• Vaughan Nelson narrows the investment universe by using value-driven screens to create a research universe of companies with market capitalizations between $1 billion and $20 billion.

• Vaughan Nelson uses fundamental analysis to construct a portfolio 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 markets securities.

• Invest in other investment companies, to the extent permitted by the Investment Company Act of 1940.

• Invest in REITs.

• 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").

Principal Investment Risks

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. Rule 144A securities may be less liquid than other equity securities. 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.

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

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. 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/Return Bar Chart and Table

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, life-of-fund 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.

Total Returns for Class Y Shares

Highest Quarterly Return:
Third Quarter 2009, 21.36%

Lowest Quarterly Return:
Third Quarter 2011, -21.12%

Average Annual Total Returns

(for the periods ended December 31, 2016)

Average Annual Total Returns - (Vaughan Nelson Value Opportunity Fund)	Past 1 Year	Past 5 Years	Life of Fund / Life of Class N	Inception Date
Class Y	6.14%	13.40%	13.30%	Oct. 31, 2008
Class Y | Return After Taxes on Distributions	5.26%	12.21%	12.40%	Oct. 31, 2008
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	4.11%	10.63%	10.89%	Oct. 31, 2008
Class A	(0.22%)	11.79%	12.20%	Oct. 31, 2008
Class C	4.03%	12.27%	12.18%	Oct. 31, 2008
Class N	6.21%		10.11%	May 01, 2013
Class T	3.22%	12.55%	12.67%	Oct. 31, 2008
Russell Midcap® Value Index	20.00%	15.70%	15.44%	Oct. 31, 2008
Russell Midcap® Value Index (5/1/13)			12.38%	May 01, 2013

The Fund did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] 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.

[3] 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 1.30%, 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 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.

[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.

[1] Other expenses are estimated for the current fiscal year.

[2] 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.

[3] 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 1.40%, 2.15%, 1.10%, 1.40% and 1.15% 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.

XML

Label

Element

Value

(Loomis Sayles Dividend Income Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

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

Expense [Heading]

rr_ExpenseHeading

Fund Fees & Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you may pay if you buy 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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 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

March 31, 2018

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 for the first year 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 35% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

35.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its assets in dividend-paying equity securities. Equity securities purchased by the Fund may include common stocks, preferred stocks, warrants, interests in real estate investment trusts ("REITs") and securities convertible into common or preferred stocks. A significant majority of the equity securities purchased by the Fund will be traded on a U.S. exchange and denominated in U.S. dollars. The Fund's non-U.S. equity investments, which will consist generally of American Depositary Receipts, but may include direct foreign investments as well, will be limited to 20% of the Fund's assets. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in U.S. equity indices published by S&P Global Ratings or Russell Investments. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

In deciding which securities to buy and sell, the Adviser seeks to identify companies that it believes are, among other things, attractively valued based on the Adviser's estimate of intrinsic value and have a strong track-record and/or potential for high dividend yield. The Adviser generally emphasizes high dividend yielding securities, but also attempts to balance risk and return and assess the future dividend paying ability of the issuers of such securities. The Adviser expects that the Fund's yield, which reflects the level of dividends paid by the Fund, will exceed the yield of the S&P 500® Index under normal market conditions. The Adviser generally seeks to find value by selecting individual stocks that it believes are attractive, rather than by attempting to achieve investment growth by rotating the Fund's holdings among various sectors of the economy.

The Fund may also purchase and sell (write) options for hedging and investment purposes and invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

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.

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 over-the-counter ("OTC") derivative transactions, such as OTC options. 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.

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 securities or other instruments denominated in, or that generate income denominated in, foreign currencies.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. 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. The Fund's focus on dividend-paying equity securities could cause the Fund to underperform the broader equity market if such securities are out of favor and a sharp rise in interest rates or an economic downturn could cause companies to reduce or eliminate their dividends. 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. Rule 144A securities may be less liquid than other equity securities.

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.

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.

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

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 comparing the Fund's one-year and life-of-fund performance with two broad measures 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 2013,11.13%

Lowest Quarterly Return:
Third Quarter 2015,-7.66%

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.

The Fund revised its investment strategies on October 15, 2014 and July 18, 2016; performance may have been different had the current investment strategies been in place for all periods shown.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Index performance reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance 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 comparing the Fund's one-year and life-of-fund performance with 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

(Loomis Sayles Dividend Income Fund) | S&P 500® Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

11.96%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend Income Fund) | Russell 1000® Value Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

17.34%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

13.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend Income 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.66%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.51%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.41%

^[2],[3]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 681

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

987

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,315

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,240

Annual Return 2013

rr_AnnualReturn2013

29.21%

Annual Return 2014

rr_AnnualReturn2014

8.08%

Annual Return 2015

rr_AnnualReturn2015

(2.61%)

Annual Return 2016

rr_AnnualReturn2016

14.19%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2013,11.13%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.13%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Third Quarter 2015,-7.66%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(7.66%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Past 1 Year

rr_AverageAnnualReturnYear01

7.67%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

9.96%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend Income Fund) | Class A | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

6.90%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

7.47%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend Income Fund) | Class A | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.89%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

7.33%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.66%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.26%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.41%

^[2],[3]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.85%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 288

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

667

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,173

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,563

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

188

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

667

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,173

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,563

Past 1 Year

rr_AverageAnnualReturnYear01

12.26%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

10.50%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.58%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.18%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.38%

^[2],[3]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.80%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 82

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

337

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

612

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,398

(Loomis Sayles Dividend 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.66%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.51%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.41%

^[2],[3]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.10%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 359

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

676

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,015

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,972

Past 1 Year

rr_AverageAnnualReturnYear01

11.38%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

10.74%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Dividend 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.66%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.26%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.41%

^[2],[3]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.85%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 87

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

359

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

652

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,486

Past 1 Year

rr_AverageAnnualReturnYear01

14.46%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

11.60%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 30, 2012

(Loomis Sayles Global Growth Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund's investment goal is long-term growth of capital.

Expense [Heading]

rr_ExpenseHeading

Fund Fees & Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you may pay if you buy 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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 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

March 31, 2018

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 for the first year 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 12% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

12.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks and depositary receipts. The Fund will invest in securities that provide exposure to no fewer than three countries, which will include the U.S. In addition, the Fund will invest at least 40% of its assets in securities of companies that maintain their principal place of business or conduct their principal business activities outside the U.S., companies that have their securities traded on non-U.S. exchanges or companies that have been formed under the laws of non-U.S. countries. Notwithstanding the foregoing, the Adviser does not consider a security to be foreign if it is included in the U.S. equity indices published by S&P Global Ratings or Russell Investments or if the security's country of risk defined by Bloomberg is the United States. The Fund may also invest up to 30% of its assets in emerging markets securities. The Fund considers a security to be an emerging markets security if its country of risk as defined by Bloomberg is included within the MSCI Emerging & Frontier Markets Index. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size.

The Fund normally invests across a wide range of sectors and industries. The Fund's portfolio manager employs a growth style of equity management, which means that the Fund seeks to invest in companies with sustainable competitive advantages, long-term structural growth drivers, attractive cash flow returns on invested capital, and management teams focused on creating long-term value for shareholders. The Fund's portfolio manager also aims to invest in companies when they trade at a significant discount to the estimate of intrinsic value.

The Fund will consider selling a portfolio investment when the portfolio manager believes an unfavorable structural change occurs within a given business or the markets in which it operates, a critical underlying investment assumption is flawed, when a more attractive reward-to-risk opportunity becomes available, when the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate.

The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"). Under normal market conditions, the Adviser does not intend to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Risk [Heading]

rr_RiskHeading

Principal Investment Risks

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.

Credit/Counterparty Risk: Credit/counterparty risk is the risk that 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 derivatives 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 over-the-counter ("OTC") derivatives transactions, such as foreign currency transactions. As a result, in instances when the Fund enters into OTC derivatives transactions, the Fund will be subject to the risk that its direct counterparties will not perform their obligations under the transactions and that the Fund will sustain losses or be unable to realize gains.

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 foreign currency forwards and foreign currency futures and invests in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. Under normal market conditions the Fund does not intend to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including foreign currency forwards, foreign currency futures and options) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities market values, interest rates or currency exchange rates. It is possible that the Fund's liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those that would have occurred had derivatives not been used. The Fund's use of derivatives, such as 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.

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. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser's assessment of the prospects for a company's growth is wrong, or if the Adviser's judgment of how other investors will value the company's growth is wrong, then the price of the company's stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock. Rule 144A securities may be less liquid than other equity securities. 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.

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.

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 the 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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Liquidity issues may also make it difficult to value the Fund's investments.

Management Risk: A strategy used by the Fund's portfolio manager 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.

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

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

(Loomis Sayles Global Growth 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

^[5]

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

1.69%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.74%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.44%

^[3],[6]

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

1,247

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,820

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 3,369

(Loomis Sayles Global Growth 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

1.38%

Total annual fund operating expenses

rr_ExpensesOverAssets

3.18%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.13%

^[3],[6]

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

874

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,566

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

3,407

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

208

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

874

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,566

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 3,407

(Loomis Sayles Global Growth 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

1.71%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.51%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.51%

^[3],[6]

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

637

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,199

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,731

(Loomis Sayles Global Growth 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

1.69%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.74%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.44%

^[3],[6]

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

945

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,538

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 3,141

(Loomis Sayles Global Growth 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

1.75%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.55%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

1.50%

^[3],[6]

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

650

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,220

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,772

(Loomis Sayles Senior Floating Rate and Fixed Income Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide a high level of current income.

Expense [Heading]

rr_ExpenseHeading

Fund Fees & Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you may pay if you buy 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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 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

March 31, 2018

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 for the first year 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 75% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

75.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in a combination of adjustable floating rate loans and other floating rate debt instruments issued by U.S. and non-U.S. corporations or other business entities and fixed-income securities, including derivatives that reference the returns of these instruments.

Under normal market conditions, the Fund will invest at least 65% of its net assets (plus any borrowings made for investment purposes) in floating rate loans that either hold a senior position in the capital structure of the borrower, hold an equal ranking with other senior debt, or have characteristics (such as a senior position secured by liens with other senior debt) that the Adviser believes justify treatment as senior debt ("Senior Loans"). The Fund may invest in Senior Loans directly as an original lender or by assignment from a lender, or it may invest indirectly through participation agreements, interests in collateralized loan obligations ("CLOs") and derivatives that reference such instruments. Derivatives that reference the returns of Senior Loans may pay returns at fixed rather than variable rates. The Fund's investments may also include, but are not limited to, subordinated loans, below investment grade corporate bonds and investment grade fixed-income debt securities. The fixed-income securities in which the Fund may invest include preferred stocks. The Fund may invest in pay-in-kind ("PIK") securities and zero-coupon securities. The Fund may receive debt, equity or other securities or instruments as a result of the general restructuring of the debt of an issuer, the restructuring of a floating rate loan or as part of a package of securities acquired with a loan.

The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its net assets (plus any borrowings made for investment purposes) in other foreign securities, including up to 10% of its net assets (plus any borrowings made for investment purposes) in emerging market securities. Although certain securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if the issuer is included in the U.S. fixed-income indices published by Bloomberg Barclays.

Floating rate loans are debt obligations that have interest rates that adjust or "float" periodically (normally on a monthly or quarterly basis) based on a generally recognized base rate, such as the London Inter-Bank Offered Rate ("LIBOR") or the prime rate offered by one or more major U.S. banks. Floating rate loans are generally unrated or rated less than investment grade and may be subject to restrictions on resale. The Fund may invest without limit in securities of any rating, including those that are in default. The Fund has no requirements as to the range of maturities of the debt instruments in which it can invest or as to the market capitalization of the issuers of those instruments.

The Fund can borrow up to one-third of the Fund's assets (including the amount borrowed) and use other techniques to purchase investments, to manage its cash flow or to redeem shares, a technique referred to as "leverage." The Fund may also use derivative instruments, including, but not limited to, futures contracts, forward contracts, swaps (including, among others, credit default swaps, credit default swap indices, loan-only credit default swaps and loan-only credit default swap indices) and structured notes to try to increase the Fund's leverage, to enhance income, to hedge against fluctuations in interest rates or currency exchange rates, and/or as a substitute for the purchase or sale of securities.

The Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"), convertible securities, exchange-traded funds ("ETFs"), and mortgage-related securities, including adjustable rate mortgage securities and collateralized mortgage obligations, asset-backed securities, and U.S. government securities (including its agencies, instrumentalities and sponsored entities). The Fund may also engage in currency-related transactions. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

When deciding which securities to buy and sell, the Adviser will consider credit quality and whether credit quality is improving or declining, as well as return potential, in the context of market and economic risks. In addition to security selection, the Adviser expects to use cycle evaluation in conjunction with sector rotation in an effort to enhance or offset cyclical influences.

The Fund is "non-diversified." As a non-diversified fund, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers, as compared with other mutual funds that are diversified.

The Fund expects to 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 return, 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.

With the exception of the 80% test described above, the percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In addition, when calculating these exposures, the Fund may use the notional value or an adjusted notional value of a derivative to reflect what the Adviser believes to be the most accurate assessment of the Fund's real economic exposure.

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Borrowing and Leverage Risk: Borrowing and other investment techniques that utilize leverage, including use of derivatives, will increase the Fund's exposure to fluctuations in the prices of its assets and, therefore, the volatility of its share price. This magnifies the potential for gain and the risk of loss. Leverage may also cause the Fund to liquidate positions at unfavorable times or prices. The costs of leverage, such as interest on borrowed funds, will increase the Fund's expenses.

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. In the event of bankruptcy of a borrower, the Fund could experience delays or limitations with respect to its ability to realize the benefits of the collateral securing a Senior Loan. Senior Loans and other floating rate securities that are rated below investment-grade are considered predominantly speculative with respect to the ability of the issuer to make timely principal and interest payments. The value of loans made to such borrowers is likely to be more sensitive to adverse news about the borrower, markets or economy. The amount of public information available with respect to Senior Loans may be less extensive than that available for registered or exchange-listed securities. The Fund will also be subject to credit risk with respect to the counterparties of its derivatives transactions.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures contracts, forward contracts, swaps and structured notes) 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 over-the-counter ("OTC") derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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.

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.

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. Senior Loans typically have adjustable interest rates. As a result, it is expected that the values of Senior Loans held by the Fund will fluctuate less in response to interest rate changes than will fixed-rate debt securities; however, the interest rates paid by these loans will generally decrease if interest rates fall. Senior Loans and other fixed-income securities are subject to the risk that borrowers pay off the debts sooner than expected, possibly requiring the Fund to re-invest in lower-yielding securities. The value of zero-coupon and pay-in-kind bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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

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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. 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.

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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Senior Loans Risk: The risks associated with Senior Loans are similar to the risks of investing in below investment-grade securities. The Senior Loans in which the Fund expects to invest will generally not be rated investment grade by the rating agencies. Economic downturns generally lead to higher non-payment rates and a Senior Loan could lose a substantial part of its value prior to default. Senior Loans are subject to credit risk, and secured Senior Loans may not be adequately collateralized. The interest rates of Senior Loans reset frequently, and thus Senior Loans are subject to interest rate risk. Senior Loans are generally less liquid than many other debt securities and there may also be less public information available about Senior Loans as compared to other debt securities. Senior Loans may be difficult to value and may be subject to restrictions on resale, irregular trading activity, wide bid/ask spreads and extended trade settlement periods. Transactions in Senior Loans may take significantly longer than seven days to settle and, as a result, proceeds related to the sale of Senior Loans may not be readily available to make additional investments or to meet the Fund's redemption obligations. In order to satisfy redemption requests pending settlement of Senior Loans, the Fund may take a variety of measures, including, without limitation drawing on its cash and other short term positions and borrowing from banks (including under the Fund's line of credit), all of which may adversely affect the Fund's performance. With limited exceptions, the Adviser will take steps intended to ensure that it does not receive material non-public information about the issuers of Senior Loans who also issue publicly traded securities, and therefore the Adviser may have less information than other investors about certain of the Senior Loans in which it seeks to invest. Investing in Senior Loan participations exposes the Fund to the credit of the counterparty issuing the participation in addition to the credit of the ultimate borrower.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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 comparing the Fund's one-year, five-year and life-of-fund performance with 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, 5.05%

Lowest Quarterly Return:
Fourth Quarter 2015, -3.02%

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.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Index performance reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance 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 comparing the Fund's one-year, five-year and life-of-fund performance with 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 Senior Floating Rate and Fixed Income Fund) | S&P / LSTA Leveraged Loan Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

10.16%

Past 5 Years

rr_AverageAnnualReturnYear05

5.11%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

5.44%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed Income Fund) | Class A

Prospectus:

rr_ProspectusTable

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.50%

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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.28%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.13%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[3],[7]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.05%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 453

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

689

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

943

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,670

Annual Return 2012

rr_AnnualReturn2012

11.82%

Annual Return 2013

rr_AnnualReturn2013

6.14%

Annual Return 2014

rr_AnnualReturn2014

2.05%

Annual Return 2015

rr_AnnualReturn2015

(1.29%)

Annual Return 2016

rr_AnnualReturn2016

11.13%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2012, 5.05%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.05%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Fourth Quarter 2015, -3.02%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.02%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2015

Past 1 Year

rr_AverageAnnualReturnYear01

7.29%

Past 5 Years

rr_AverageAnnualReturnYear05

5.11%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

5.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed Income Fund) | Class A | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.62%

Past 5 Years

rr_AverageAnnualReturnYear05

2.57%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed Income Fund) | Class A | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.04%

Past 5 Years

rr_AverageAnnualReturnYear05

2.79%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.21%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.28%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.88%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[3],[7]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.80%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 283

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

583

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,009

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,194

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

183

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

583

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,009

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,194

Past 1 Year

rr_AverageAnnualReturnYear01

9.34%

Past 5 Years

rr_AverageAnnualReturnYear05

5.08%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

5.57%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.21%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.81%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.06%

^[3],[7]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.75%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 77

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

253

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

444

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 996

(Loomis Sayles Senior Floating Rate and Fixed 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.28%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.13%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[3],[7]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.05%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 354

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

592

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

849

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,583

Past 1 Year

rr_AverageAnnualReturnYear01

8.39%

Past 5 Years

rr_AverageAnnualReturnYear05

5.31%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

5.86%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed 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

0.60%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.28%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.88%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.08%

^[3],[7]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.80%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 82

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

273

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

480

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,077

Past 1 Year

rr_AverageAnnualReturnYear01

11.51%

Past 5 Years

rr_AverageAnnualReturnYear05

6.12%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

6.63%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Vaughan Nelson Select 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 41 of the Prospectus, in Appendix A to the Prospectus and on page 101 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

March 31, 2019

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 its most recently ended fiscal year, the Fund's portfolio turnover rate was 64% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

64.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund, under normal market conditions, will invest primarily in equity securities, including common stocks, preferred stocks, limited partnership interests, interests in limited liability companies, real estate investment trusts ("REITs") or other trusts and similar securities. The Fund is non-diversified, which means that it may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers than a diversified fund. Typically, the Fund's portfolio will hold 20 to 40 securities. The Fund may invest in companies with any market capitalization, although, it will typically focus its investments in mid- to large- capitalization companies. When opportunities present themselves, the Fund may establish short positions in specific equity securities or indices. While the Fund typically invests in equity securities, it may also invest in debt securities, including below investment grade fixed-income securities (commonly known as "junk bonds"). A fixed-income security is considered below investment grade quality when none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their top four ratings categories.

Vaughan Nelson invests in companies of all market capitalizations 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 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:

• Vaughan Nelson employs a value-driven investment philosophy that selects securities 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 the entire U.S. exchange-traded equity investment universe. Vaughan Nelson then narrows the investment universe by using fundamental analysis to construct a portfolio of 20 to 40 securities.

• Vaughan Nelson uses fundamental analysis to construct a portfolio 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 also employ its value driven investment philosophy to identify out-of-favor or misunderstood debt securities.

• 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 also may:

• Invest in convertible preferred stock and convertible debt securities.

• Invest in publicly traded master limited partnerships.

• Invest in foreign securities, including emerging market securities, traded in U.S. markets directly or through depositary receipt programs such as American Depositary Receipts ("ADRs") and Global Depositary Receipts ("GDRs").

• Invest in REITs.

• 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 derivative securities, such as options, for hedging and investment purposes.

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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 derivatives 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 over-the-counter ("OTC") derivatives transactions, such as foreign currency transactions. As a result, in instances when the Fund enters into OTC derivatives 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) 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 OTC derivatives, the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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.

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. 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 market 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. Taking short positions in stocks also results in a form of 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 significant liquidity risk because they are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. 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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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.

Short Sale Risk: Short sales can increase the volatility of the Fund and may lower the Fund's return or result in losses, which potentially may be unlimited. If the Fund is unable to borrow securities in connection with a short sale at an advantageous time or price, the Fund may be limited in its ability to pursue its short sale strategy or may incur losses. The use of short sales also exposes the Fund to leverage risk.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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 comparing the Fund's one-year and life-of-fund performance with 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 2013,12.67%

Lowest Quarterly Return:
Third Quarter 2015,-6.28%

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.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. 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 shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.

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 comparing the Fund's one-year and life-of-fund performance with 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 Select Fund) | S&P 500® Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

11.96%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

14.09%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select 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

0.27%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.37%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.12%

^[3],[8]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 695

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

963

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,262

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,108

Annual Return 2013

rr_AnnualReturn2013

43.12%

Annual Return 2014

rr_AnnualReturn2014

10.49%

Annual Return 2015

rr_AnnualReturn2015

2.48%

Annual Return 2016

rr_AnnualReturn2016

6.72%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2013,12.67%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

12.67%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2013

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Third Quarter 2015,-6.28%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(6.28%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Past 1 Year

rr_AverageAnnualReturnYear01

0.58%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.94%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select Fund) | Class A | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.20%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

11.38%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select Fund) | Class A | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.66%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

9.71%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select 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

0.27%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.12%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.12%

^[3],[8]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

2.00%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 303

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

642

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,118

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,434

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

203

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

642

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,118

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,434

Past 1 Year

rr_AverageAnnualReturnYear01

4.93%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

13.59%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select 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

0.21%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.06%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.11%

^[3],[8]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.95%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 97

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

317

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

565

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,275

(Vaughan Nelson Select 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

0.27%

^[4]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.37%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.12%

^[3],[8]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.25%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 374

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

651

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

960

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,836

Past 1 Year

rr_AverageAnnualReturnYear01

4.05%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

13.78%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select 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

0.27%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.12%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.12%

^[3],[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

334

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

595

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,343

Past 1 Year

rr_AverageAnnualReturnYear01

6.94%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

14.73%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(ASG Dynamic Allocation Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation. The secondary goal of the Fund is the protection of capital during unfavorable market conditions.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 its most recently ended fiscal year, the Fund's portfolio turnover rate was 115% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

115.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund tactically allocates its investments across a range of asset classes and global markets. Under normal market conditions, the Adviser will typically use a variety of derivative instruments, including equity, fixed-income and currency futures contracts and currency forward contracts, as well as exchange-traded funds ("ETFs") and money market and other short-term, high-quality securities, to achieve exposures to the following asset classes: (i) U.S. equity securities; (ii) foreign developed market equity securities; (iii) emerging market equity and fixed-income securities; (iv) U.S. fixed-income securities; and (v) foreign developed market fixed-income securities. 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 will typically obtain its target allocations through the use of long positions in futures and/or forward contracts, as well as investments in ETFs, which can provide exposure to certain asset classes that may not be readily available via futures contracts (e.g., domestic and international corporate bonds). The Fund may also hold short positions through the use of derivatives for hedging purposes. The Fund may obtain exposure to below investment grade fixed-income securities, also known as "junk bonds," through its investments in ETFs. Below investment grade fixed-income securities are rated below investment grade quality (i.e., none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their respective top four ratings categories).

In deciding which investments to buy and sell, the Adviser uses a quantitative systematic approach which analyzes multiple time periods. The approach consists of overweighting and/or underweighting allocations to asset classes based on a number of factors, including momentum signals, changes in hedge fund positioning, and/or market volatility. For example, the Adviser may overweight an asset class that demonstrates increasing momentum and/or hedge fund exposure relative to other asset classes. In estimating changes in hedge fund positioning, the Adviser may use various approaches, including an analysis of the returns of hedge funds included in one or more commercially available databases selected by the Adviser (for example, the Lipper TASS hedge fund database). When determining allocations to asset classes, the Adviser will also take into consideration correlations between assets and the volatilities of these assets. The minimum exposure to each asset class may be as low as 0% of total assets.

The Adviser separately manages the Fund's investments in derivatives and ETFs (the "Dynamic Allocation Portion") and the Fund's investments in money market and other short-term, high-quality securities (the "Money Market Portion," described further below). The Dynamic Allocation Portion will obtain economic leverage through the use of derivative instruments. Leverage can vary over time based on market conditions and the net notional value of the Dynamic Allocation Portion's investment exposure will not exceed 200% of the Fund's total assets. The Fund's total investment exposure may be greater than 200% of the Fund's total assets because it includes exposures obtained through both the Dynamic Allocation Portion and the Money Market Portion. Because the Fund's investment exposure will often exceed its total assets, it will be subject to increased risk compared to funds that do not leverage their investment exposure. While this increased investment exposure may magnify the Fund's potential for gains, it will also magnify the potential for losses. For these reasons, the Fund is intended for long-term investors.

The Adviser will seek to manage the annualized volatility (a statistical measure of the variation of returns) of the Fund's overall portfolio as part of the investment approach. The Adviser will monitor the portfolio daily, and will generally seek an annualized volatility level of no greater than 20% (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may significantly exceed 20% for various reasons, including changes in market levels of volatility and investments in instruments that are inherently volatile. This would increase the risk of investing in the Fund.

The Fund expects that, under normal market conditions, it will invest at least 40% of its total assets in the Money Market Portion. The Fund may invest less than this percentage in the Money Market Portion and the Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to provide collateral for the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value. The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit, repurchase agreements and time deposits) of issuers in that industry.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities; (ii) securities issued by foreign governments, their political subdivisions, agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

The Fund expects to add commodities as an available asset class for investment at a future date. Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives by investing in a wholly-owned subsidiary expected to be organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). The Fund anticipates registering the Commodity Subsidiary upon the attainment of approximately $100 million in assets under management. The maximum exposure to commodities will be 20% of total assets.

The Fund is non-diversified, which means that it may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Because the Fund may invest in the securities of a limited number of issuers, an investment in the Fund may involve a higher degree of risk than would be present in a diversified portfolio.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders.

Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to 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.

Allocation Risk: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary will not be registered under the Investment Company Act of 1940 (the "1940 Act") and will not be subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund is organized and the Commodity Subsidiary is expected to be organized, respectively, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to commodities markets, 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative or the underlying assets decrease in value over time.

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. 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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including ETFs, in which it invests in addition to its own expenses. In addition, investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial loss.

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. The Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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 the Fund's performance in the first full year and by showing how the Fund's average annual returns for the one-year and Life-of-Fund periods compare to those of two broad measures of market performance. The Blended Index is an unmanaged, blended index composed of the following weights: 60% MSCI World Index (Net) and 40% Bloomberg Barclays U.S. Aggregate Bond Index. The two indices composing the Blended Index measure, respectively, the performance of global equity securities and global sovereign fixed-income securities. 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 2016, 1.83%

Lowest Quarterly Return:
First Quarter 2016, -0.41%

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 T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

Index performance reflects no deduction for fees, expenses or taxes.

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

Actual after-tax returns depend on an investor's tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance 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 the Fund's performance in the first full year and by showing how the Fund's average annual returns for the one-year and Life-of-Fund 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

(ASG Dynamic Allocation Fund) | Morningstar Global Allocation Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

7.00%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

5.37%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation Fund) | Blended Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

5.71%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

4.09%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation 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

^[9]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.85%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.06%

^[10]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.86%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.63%

^[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

1,068

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,468

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,581

Past 1 Year

rr_AverageAnnualReturnYear01

(3.46%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

(4.35%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation 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

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.81%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.06%

^[10]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.57%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.60%

^[11]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.97%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 300

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

743

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,312

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,860

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

200

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

743

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,312

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,860

Past 1 Year

rr_AverageAnnualReturnYear01

0.63%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.21%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation 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

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.85%

^[12]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.06%

^[10]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.86%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.63%

^[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

755

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,169

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,321

Past 1 Year

rr_AverageAnnualReturnYear01

(0.12%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

(1.35%)

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation 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

0.70%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.84%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.06%

^[10]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.60%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.63%

^[11]

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

443

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

811

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,847

Annual Return 2016

rr_AnnualReturn2016

2.57%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Third Quarter 2016, 1.83%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

1.83%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2016

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: First Quarter 2016, -0.41%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(0.41%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2016

Past 1 Year

rr_AverageAnnualReturnYear01

2.57%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.17%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

2.42%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.98%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Dynamic Allocation Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

1.45%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.81%

Inception Date

rr_AverageAnnualReturnInceptionDate

Nov. 30, 2015

(ASG Global Alternatives Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund pursues an absolute return strategy that seeks to provide capital appreciation consistent with the risk-return characteristics of a diversified portfolio of hedge funds. The secondary goal of the Fund is to achieve these returns with less volatility than major equity indices.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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, 2019

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 examples for Class A, Class C, Class T and Class Y are 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. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate.

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund seeks to achieve long and short exposure to global equity, bond, currency and commodity markets through a wide range of derivative instruments and direct investments. Under normal market conditions, the Adviser typically will make extensive use of derivative instruments, in particular futures and forward contracts on global equity and fixed-income securities, securities indices (including both broad- and narrow-based securities indices), currencies, commodities and other instruments. These investments are intended to provide the Fund with risk and return characteristics similar to those of a diversified portfolio of hedge funds.

The Fund seeks to generate absolute returns over time rather than track the performance of any particular index of hedge fund returns. In selecting investments for the Fund, the Adviser uses quantitative models to estimate the market exposures that drive the aggregate returns of a diverse set of hedge funds. These market exposures may include, for example, exposures to the returns of stocks, fixed-income securities (including U.S. and non-U.S. government securities), currencies and commodities. In estimating these market exposures, the Adviser may use various approaches, including an analysis of the returns of hedge funds included in one or more commercially available databases selected by the Adviser (for example, the Lipper TASS hedge fund database), and seeks to use a variety of derivative instruments to capture such exposures in the aggregate while adding value through dynamic allocation among market exposures and volatility management. The Adviser will have great flexibility to allocate the Fund's derivatives exposure among various securities, indices, currencies, commodities and other instruments; the amount of the Fund's assets that may be allocated to derivative strategies and among these various instruments is expected to vary over time. When buying and selling securities and other instruments for the Fund, and in determining the amount of assets to be allocated to the Money Market Portion (as defined below), the Adviser also may consider other factors, such as: (i) the Fund's obligations under its various derivative positions; (ii) redemption requests; (iii) yield management; (iv) credit management; and (v) volatility management. The Fund will not invest directly in hedge funds. The Fund may invest in non-U.S. securities and instruments and securities and instruments traded outside the United States, and expects to engage in non-U.S. currency transactions.

The Adviser currently targets an annualized volatility level of 9% or less (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed its target volatility for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

Under normal market conditions, it is expected that no more than 25% of the Fund's total assets will be dedicated to initial and variation margin payments relating to the Fund's derivative transactions. The gross notional value of the Fund's derivative investments, however, will generally exceed 25% of the Fund's assets, and may significantly exceed the total value of the Fund's assets. The Fund expects that under normal market conditions it will invest at least 75% of its total assets in money market and other short-term, high-quality securities (the "Money Market Portion"), although the Fund may invest less than this percentage. The Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to finance the Fund's investments in derivatives and similar instruments and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities ("U.S. Government Obligations"); (ii) securities issued by foreign governments, their political subdivisions or agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks, and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives through a wholly-owned subsidiary organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). Under normal market conditions, no more than 10% of the Fund's total assets will be dedicated to initial and variation margin payments relating to these transactions.

The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit) of issuers in such industry. The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to 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.

Allocation Risk: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary is not registered under the Investment Company Act of 1940 (the "1940 Act") and is not subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund and the Commodity Subsidiary, respectively, are organized, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

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.

Hedge Fund Risk: Hedge funds are typically unregulated private investment pools available only to sophisticated investors. They are often illiquid and highly leveraged. Although the Fund will not invest directly in hedge funds, because the Fund's investments are intended to provide exposure to the factors that drive hedge fund returns, an investment in the Fund will be subject to many of the same risks associated with an investment in a diversified portfolio of hedge funds. Therefore, the Fund's performance may be lower than the returns of the broader stock market and the Fund's net asset value may fluctuate substantially over time.

Index/Tracking Error Risk: Although the Fund does not seek to track any particular index, the Fund seeks to analyze the factors that drive hedge fund returns, as determined by reference to one or more indices. These indices may not provide an accurate representation of hedge fund returns generally, and the Adviser's strategy may not successfully identify or be able to replicate factors that drive returns. There is a risk that hedge fund return data provided by third party hedge fund index providers may be inaccurate or may not accurately reflect hedge fund returns due to survivorship bias, self-reporting bias or other biases.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

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, Life-of-Fund and Life-of-Class 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 2010, 7.23%

Lowest Quarterly Return:
First Quarter 2016, -8.36%

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 T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. 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 shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.

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, Life-of-Fund and Life-of-Class 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

(ASG Global Alternatives Fund) | Barclay Fund of Funds Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.32%

Past 5 Years

rr_AverageAnnualReturnYear05

3.27%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.59%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives Fund) | Barclay Fund of Funds Index (5/1/13)

Prospectus:

rr_ProspectusTable

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.05%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 01, 2013

(ASG Global Alternatives 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

^[9]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

1.14%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.18%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.57%

^[13]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[14]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.56%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 725

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,040

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,379

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,333

Past 1 Year

rr_AverageAnnualReturnYear01

(9.89%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.68%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.15%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives 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

1.14%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.18%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.32%

^[13]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[14]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

2.31%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 334

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

723

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,239

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,654

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

234

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

723

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,239

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,654

Past 1 Year

rr_AverageAnnualReturnYear01

(6.09%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.11%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.11%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives 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

1.14%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.10%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.24%

^[13]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[14]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.24%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 126

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

393

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

681

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,500

Past 1 Year

rr_AverageAnnualReturnYear01

(4.05%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.32%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 01, 2013

(ASG Global Alternatives 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

1.14%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.18%

^[12]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.57%

^[13]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[14]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.56%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 405

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

732

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,082

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,069

Past 1 Year

rr_AverageAnnualReturnYear01

(6.79%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.38%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.56%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives 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

1.14%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.18%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.32%

^[13]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[14]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.31%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 133

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

416

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

722

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,589

Annual Return 2009

rr_AnnualReturn2009

9.10%

Annual Return 2010

rr_AnnualReturn2010

7.22%

Annual Return 2011

rr_AnnualReturn2011

(3.00%)

Annual Return 2012

rr_AnnualReturn2012

3.68%

Annual Return 2013

rr_AnnualReturn2013

16.05%

Annual Return 2014

rr_AnnualReturn2014

3.77%

Annual Return 2015

rr_AnnualReturn2015

(2.38%)

Annual Return 2016

rr_AnnualReturn2016

(4.23%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Third Quarter 2010, 7.23%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

7.23%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2010

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: First Quarter 2016, -8.36%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(8.36%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Mar. 31, 2016

Past 1 Year

rr_AverageAnnualReturnYear01

(4.23%)

Past 5 Years

rr_AverageAnnualReturnYear05

3.14%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.13%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(4.23%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.99%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.21%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Global Alternatives Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(2.39%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.11%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.20%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2008

(ASG Managed Futures Strategy Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund pursues an absolute return strategy that seeks to provide 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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate.

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund seeks to generate positive absolute returns over time. Under normal market conditions, the Adviser typically will make extensive use of a variety of derivative instruments, including futures and forward contracts, to capture the exposures suggested by its absolute return strategy while also seeking to add value through volatility management. These market exposures, which are expected to change over time, may include, for example, exposures to the returns of U.S. and non-U.S. equity and fixed-income securities indices (including both broad- and narrow-based securities indices), currencies and commodities. The Adviser will have great flexibility to allocate the Fund's derivatives exposure among various securities, indices, currencies, commodities and other instruments; the amount of the Fund's assets that may be allocated to derivative strategies and among these various instruments is expected to vary over time. The Adviser uses proprietary quantitative models to identify price trends in equity, fixed-income, currency and commodity instruments across time periods of various lengths. The Adviser believes that asset prices may show persistent trending behavior due to a number of behavioral biases among market participants as well as certain risk-management policies that will identify assets to purchase in upward-trending markets and identify assets to sell in downward-trending markets. The Adviser believes that following trends across a widely diversified set of assets, combined with active risk management, may allow it to earn a positive expected return over time. The Fund may have both "short" and "long" exposures within an asset class based upon the Adviser's analysis of multiple time horizons to identify trends in a particular asset class. A "short" exposure will benefit when the underlying asset class decreases in price. A "long" exposure will benefit when the underlying asset class increases in price. The Adviser will scale the notional exposure of the Fund's futures and currency forward positions with the objective of targeting a relatively stable level of annualized volatility for the Fund's overall portfolio. The Adviser currently targets an annualized volatility level of 17% or less (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed its target volatility for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

Under normal market conditions, it is expected that no more than 25% of the Fund's total assets will be dedicated to initial and variation margin payments relating to the Fund's derivative transactions. The gross notional value of the Fund's derivative investments, however, will generally exceed 25% of the Fund's total assets, and may significantly exceed the total value of the Fund's assets. The Fund expects that under normal market conditions it will invest at least 75% of its total assets in money market and other short-term, high-quality securities (such as bankers' acceptances, certificates of deposit, commercial paper, loan participations, repurchase agreements and time deposits) (the "Money Market Portion"), although the Fund may invest less than this percentage. The Adviser will determine the percentage of the Fund's assets that will be invested in the Money Market Portion at any time. The assets allocated to the Money Market Portion will be used primarily to support the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. Although the Fund will invest a significant portion of its assets in money market instruments, the Fund is not a "money market" fund and the value of the Money Market Portion as well as the value of the Fund's shares may decrease. The Fund is not subject to the portfolio quality, maturity and net asset value requirements applicable to money market funds, and the Fund will not seek to maintain a stable net asset value. The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit, repurchase agreements and time deposits) of issuers in such industry.

The Adviser will only invest the assets of the Money Market Portion in high-quality securities which are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in: (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities ("U.S. Government Obligations"); (ii) securities issued by foreign governments, their political subdivisions, agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic banks, foreign branches of domestic banks, foreign subsidiaries of domestic banks and domestic and foreign branches of foreign banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

Although the Fund does not intend to invest in physical commodities directly, the Fund expects to obtain investment exposure to commodities and commodity-related derivatives by investing in a wholly-owned subsidiary organized under the laws of the Cayman Islands that will make commodity-related investments (the "Commodity Subsidiary"). Under normal market conditions, no more than 10% of the Fund's total assets will be dedicated to initial and variation margin payments relating to these transactions.

Although the Fund seeks positive absolute returns over time, it is likely that the Fund's investment returns may be volatile over short periods of time. The Fund may outperform the overall securities market during periods of flat or negative market performance and may underperform during periods of strong market performance. There can be no assurance that the Fund's returns over time or during any period will be positive or that the Fund will outperform the overall security markets over time or during any particular period.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. Due to the short-term nature of the Fund's investment portfolio, the Fund does not calculate a portfolio turnover rate. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs which reduce fund returns.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to 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.

Allocation Risk: This is the risk that the Adviser's judgments about, and allocations between, asset classes and market exposures may adversely affect the Fund's performance. This risk can be increased by the use of derivatives to increase allocations to various market exposures. This is because derivatives can create investment leverage, which will magnify the impact to the Fund of its investment in any underperforming market exposure.

Commodity Risk: This is the risk that exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of physical commodities or commodity-linked derivative instruments may be affected by changes in overall market movements, commodity price volatility, changes in interest rates, currency fluctuations, or factors affecting a particular industry or commodity, such as drought, floods, weather, livestock disease, embargoes, tariffs and international economic, political and regulatory developments.

Commodity Subsidiary Risk: Investing in the Commodity Subsidiary will indirectly expose the Fund to the risks associated with the Commodity Subsidiary's investments, such as commodity risk. The Commodity Subsidiary is not registered under the Investment Company Act of 1940 (the "1940 Act") and is not subject to all of the investor protections of the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands, under which the Fund and the Commodity Subsidiary, respectively, are organized, could negatively affect the Fund and its shareholders.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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.

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 a significant portion of its assets 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures and forward contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures, forward contracts, and other foreign currency transactions and commodity-linked derivatives involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

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 market 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. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

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 and Life-of-Fund periods compare to those of two broad measures 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:
First Quarter 2015, 11.72%

Lowest Quarterly Return:
Second Quarter 2015, -10.57%

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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. 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 shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the one-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.

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 and Life-of-Fund 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

(ASG Managed Futures Strategy Fund) | Credit Suisse Managed Futures Liquid Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.19%

Past 5 Years

rr_AverageAnnualReturnYear05

4.33%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.59%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy Fund) | SG Trend Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(6.19%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.16%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy 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

^[9]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

1.24%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.75%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[15],[16]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.74%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 742

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,093

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,468

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,518

Past 1 Year

rr_AverageAnnualReturnYear01

(11.09%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.32%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.07%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy 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

1.24%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.26%

Total annual fund operating expenses

rr_ExpensesOverAssets

2.50%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[15],[16]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

2.49%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 352

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

778

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,330

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,835

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

252

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

778

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,330

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,835

Past 1 Year

rr_AverageAnnualReturnYear01

(7.39%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.73%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.22%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy 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

1.24%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.15%

^[12]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.39%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[15],[16]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.39%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 142

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

440

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

761

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,669

(ASG Managed Futures Strategy 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

1.24%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.26%

^[12]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.75%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[15],[16]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.74%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 422

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

786

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,174

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,260

Past 1 Year

rr_AverageAnnualReturnYear01

(8.08%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.00%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.61%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy 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

1.24%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.26%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.50%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.01%

^[15],[16]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.49%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 152

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

473

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

818

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,790

Annual Return 2011

rr_AnnualReturn2011

0.57%

Annual Return 2012

rr_AnnualReturn2012

(10.90%)

Annual Return 2013

rr_AnnualReturn2013

12.75%

Annual Return 2014

rr_AnnualReturn2014

22.21%

Annual Return 2015

rr_AnnualReturn2015

(1.22%)

Annual Return 2016

rr_AnnualReturn2016

(5.47%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2015, 11.72%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

11.72%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2015

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Second Quarter 2015, -10.57%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(10.57%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Jun. 30, 2015

Past 1 Year

rr_AverageAnnualReturnYear01

(5.47%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.77%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

4.26%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(5.48%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.42%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.70%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Managed Futures Strategy Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(3.10%)

Past 5 Years

rr_AverageAnnualReturnYear05

1.70%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.82%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jul. 30, 2010

(ASG Tactical U.S. Market Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation, with emphasis on the protection of capital during unfavorable market conditions.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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, 2019

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 its most recently ended fiscal year, the Fund's portfolio turnover rate was 42% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

42.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund pursues its investment goal primarily through investments in equity securities that broadly represent the U.S. equities market (including common stocks, preferred stocks and exchange-traded funds ("ETFs") related to equity investments); derivative instruments related to the U.S. equities market (primarily futures contracts on U.S. equity indices); and fixed-income securities (including money market and other short-term or variable-rate, high-quality securities and related ETFs). Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investments that are tied economically to the U.S. The Adviser considers an investment to be tied economically to the U.S. if the investment is included in an index representative of the U.S., the investment's returns are linked to the performance of such an index, or the investment is exposed to the economic risks and returns of the U.S. The Adviser may use quantitative models to determine when to magnify the Fund's exposure to the U.S. equity market, for example, through the purchase of futures contracts, or, alternatively, when to decrease such exposure, for example, through the sale of futures contracts or through the purchase of ETFs that it believes may effectively hedge equity investments. The Adviser may increase the Fund's exposure to the U.S. equity market to up to 130% of the Fund's total assets when it believes that the risk of loss is justified by potential returns. The Adviser may decrease such exposure to as little as 0% of the Fund's total assets, in an attempt to limit the effects of extreme market drawdowns, when it believes that the risk of loss is not offset by potential returns. Such increases and decreases may lag changes in the market, and there is no guarantee that the Adviser's models will accurately predict market movement. Because the Fund's equity market exposure will often exceed its total assets, it will be subject to increased risk compared to funds that do not leverage their equity market exposure. While this increased exposure to equity investments may magnify the Fund's potential for gains, it also may magnify the potential for loss. For these reasons, the Fund is intended for long-term investors.

Equity Securities Investments. The equity securities portion of the Fund is managed by NGAM Advisors, L.P. (through its division, Active Index Advisors®) ("NGAM Advisors"), with the exception of any investments in ETFs, which are selected by the Adviser. NGAM Advisors utilizes a proprietary sampling system when deciding which securities to purchase, with the goal of tracking the performance of the large-capitalization U.S. equity market. In an attempt to reduce adverse tax consequences, the portion of the Fund managed by NGAM Advisors may hold securities that are not considered to represent the large-capitalization U.S. equity market, or hold securities in amounts disproportionate to their weights within the large-capitalization U.S. equity market. The portfolio may experience tracking error and is not guaranteed to replicate exactly the large-capitalization U.S. equity market.

Derivative Investments. As discussed above, the Adviser seeks to complement the equity portion of the Fund with investments in derivative instruments intended to enhance return and, during times of significant market decline, mitigate losses. In addition, the Adviser uses futures contracts to manage volatility and adjusts the Fund's exposure to equity investments in times of significantly increased volatility (including, when volatility is more than double the long-term average volatility of the U.S. equity markets). As of March 31, 2017, the long-term average annualized volatility of the U.S. equity markets was 18.0%. The Fund's actual or realized volatility during certain periods or over time may materially exceed the long-term average annualized volatility of the U.S. equity markets, for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. The Fund may have both "short" and "long" exposures to equity investments simultaneously. The Fund will benefit from a "short" exposure when equity and equity-related investments decrease in price, and will benefit from a "long" exposure when equity and equity-related investments increase in price.

Fixed-Income Investments. The assets allocated to the fixed-income portion will be used primarily to support the Fund's investments in derivatives and, secondarily, to provide the Fund with incremental income and liquidity. The fixed-income portion of the Fund will only invest in high-quality securities that are denominated in U.S. dollars, and will select securities for investment based on various factors, including the security's maturity and rating. The Adviser will invest primarily in (i) short-term obligations issued or guaranteed by the United States government, its agencies or instrumentalities; (ii) securities issued by foreign governments, their political subdivisions or agencies or instrumentalities; (iii) certificates of deposit, time deposits and bankers' acceptances issued by domestic and foreign banks, including domestic or foreign branches or subsidiaries of such banks; (iv) variable amount master demand notes; (v) participation interests in loans extended by banks to companies; (vi) commercial paper or similar debt obligations; and (vii) repurchase agreements.

When buying and selling securities and other instruments for the Fund, and when allocating assets to NGAM Advisors, the Adviser may consider: (i) the Adviser's proprietary quantitative models, including the outlook on volatility and market decline; (ii) the Fund's obligations under its various derivative positions; (iii) redemption requests; (iv) yield management; (v) credit management; and (vi) volatility management.

The Fund will concentrate its investments in the financial services industry, which means it will normally invest at least 25% of its total assets in securities and other obligations (for example, bank certificates of deposit) of issuers in such industry.

The Fund may 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance. The Fund's trading in derivatives is active and frequent. Active and frequent trading of derivatives, like active and frequent trading of securities, will result in transaction costs that reduce Fund returns.

With the exception of the Fund's 80% policy, the percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In accordance with applicable requirements of the U.S. Securities and Exchange Commission (the "SEC"), the Fund will notify shareholders prior to any change to the 80% policy discussed above taking effect.

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.

Concentrated Investment Risk: The Fund is particularly vulnerable to events affecting companies in the financial services industry because the Fund concentrates its investments in securities and other obligations of issuers in such industry. Examples of risks affecting the financial services industry include changes in governmental regulation, issues relating to the availability and cost of capital, changes in interest rates and/or monetary policy and price competition. In addition, financial services companies are often more highly leveraged than other companies, making them inherently riskier. As a result, the Fund's shares may rise and fall in value more rapidly and to a greater extent than shares of a fund that does not concentrate or focus in a particular industry or economic sector.

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 over-the-counter ("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 futures contracts) are subject to changes in the value of the underlying assets or indices on which such instruments are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund's exposure to securities 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, such as futures contracts, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

Equity Securities Risk: The value of the Fund's investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

Index/Tracking Error Risk: This is the risk that, to the extent the Fund's principal investment strategies utilize indices, the Fund's performance may not track the performance of such indices. For example, the equity securities in which the Fund invests may not provide investment performance matching the performance of broad-based large capitalization U.S. equity indices. Similarly, changes in the value of the derivatives in which the Fund invests may not correlate perfectly with the underlying assets or indices associated with such derivatives. Moreover, the ETFs in which the Fund invests may not replicate the performance of the indices they track and may, therefore, result in loss to the Fund.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

Investments in Other Investment Companies Risk: The Fund will indirectly bear the management, service and other fees of any other investment companies, including ETFs, in which it invests in addition to its own expenses. In addition, investments in ETFs have unique characteristics, including, but not limited to, the expense structure and additional expenses associated with investing in ETFs.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in securities results in a form of 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. The Adviser utilizes various proprietary quantitative models to identify investment opportunities. There is a possibility that one or all of the quantitative models may fail to identify profitable opportunities at any time. Furthermore, they may incorrectly identify opportunities and these misidentified opportunities may lead to substantial losses.

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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

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

Valuation Risk: This is the risk that the Fund has valued certain securities at a higher price than the price at which they can be sold. This risk may be especially pronounced for investments, such as derivatives, that may be illiquid or may become illiquid.

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 and Life-of-Fund periods compare to those of two broad measures 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:
Second Quarter 2014, 6.19%

Lowest Quarterly Return:
Third Quarter 2015, -6.50%

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 T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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.

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 and Life-of-Fund 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

(ASG Tactical U.S. Market Fund) | S&P 500® Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

11.96%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

11.53%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market Fund) | Barclay Equity Long/Short Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

1.71%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.64%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market 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

^[9]

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

0.35%

^[17]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.40%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.16%

^[18]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.24%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 694

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

965

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,270

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,134

Past 1 Year

rr_AverageAnnualReturnYear01

(1.93%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

6.65%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market 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

0.35%

^[17]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.15%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.16%

^[18]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.99%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 302

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

644

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,127

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,459

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

202

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

644

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,127

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,459

Past 1 Year

rr_AverageAnnualReturnYear01

2.39%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

7.82%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market 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

0.35%

^[17],[19]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.40%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.16%

^[18]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.24%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 373

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

653

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

969

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,862

Past 1 Year

rr_AverageAnnualReturnYear01

1.51%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

7.76%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market 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

0.35%

^[17]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.15%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.16%

^[18]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.99%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 101

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

336

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

604

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,371

Annual Return 2014

rr_AnnualReturn2014

14.92%

Annual Return 2015

rr_AnnualReturn2015

(2.74%)

Annual Return 2016

rr_AnnualReturn2016

4.41%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Second Quarter 2014, 6.19%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

6.19%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2014

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Third Quarter 2015, -6.50%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(6.50%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2015

Past 1 Year

rr_AverageAnnualReturnYear01

4.41%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

8.90%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.24%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

7.91%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(ASG Tactical U.S. Market Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

2.65%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

6.73%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2013

(Loomis Sayles Strategic Alpha Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks to provide an attractive absolute total return, complemented by prudent investment management designed to manage risks and protect investor capital. The secondary goal of the Fund is to achieve these returns with relatively low volatility.

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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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, 2019

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 72% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

72.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

The Fund has an absolute total return investment objective, which means that it is not managed relative to an index and that it attempts to achieve positive total returns over a full market cycle. The Fund intends to pursue its objective by utilizing a flexible investment approach that allocates investments across a global range of investment opportunities related to credit, currencies and interest rates, while employing risk management strategies to mitigate downside risk. The Fund may invest up to 100% of its total assets in below investment grade fixed-income securities (also known as "junk bonds") and derivatives that have returns related to the returns on below investment grade fixed-income securities, although it is expected that, under normal market conditions, the Fund's net exposure (i.e., long exposures obtained through direct investments in securities and in derivatives minus short exposures obtained through derivatives) to below investment grade fixed-income assets generally will not exceed 50% of the Fund's total assets. Below investment-grade fixed-income securities are rated below investment-grade quality (i.e., none of the three major rating agencies (Moody's Investors Service, Inc., Fitch Investor Services, Inc. or S&P Global Ratings) have rated the securities in one of their respective top four ratings categories). Under normal market conditions, the Fund also may invest up to 50% of its total assets in investments denominated in non-U.S. currencies and related derivatives, including up to 20% in investments denominated in emerging market currencies and related derivatives. The Fund expects that its exposure to these asset classes will often be obtained substantially through the use of derivative instruments. The Fund defines an "emerging market currency" as a currency of a country that carries a sovereign debt quality rating that is rated below investment grade by either S&P or Moody's, or is unrated by both S&P and Moody's. Currency positions that are intended to hedge the Fund's non-U.S. currency exposure (i.e., currency positions that are not made for investment purposes) will offset positions in the same currency that are made for investment purposes when calculating the limitation on investments in non-U.S. and emerging market currency investments because the Fund believes that hedging a currency position is likely to negate some or all of the currency risk associated with the original currency position. The Fund does not have limits on the duration of its portfolio, and the Fund's duration will change over time. The Fund also may invest in preferred stocks.

In selecting investments for the Fund, the Adviser develops long-term portfolio themes driven by macro-economic indicators. These include global economic trends, demographic trends and labor supply, analysis of global capital flows and assessments of geopolitical factors. The Adviser then develops shorter-term portfolio strategies based on factors including, but not limited to, economic, credit and Federal Reserve cycles, and top-down sector valuations and bottom-up security valuations. The Adviser seeks to actively manage risk, with a focus on managing the Fund's exposure to credit, interest rate and currency risks in relation to the market. Additionally, the portfolio managers will use risk management tools, such as models that evaluate risk correlation to various market factors or asset classes, to seek to manage risk on an ongoing basis. 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 Adviser currently targets an annualized volatility range of 4% to 6% (as measured by the standard deviation of the Fund's returns). The Fund's actual or realized volatility during certain periods or over time may materially exceed or be lower than its target volatility range for various reasons, including changes in market levels of volatility and because the Fund's portfolio may include instruments that are inherently volatile. This would increase the risk of investing in the Fund.

The Fund will pursue its investment goal by obtaining long investment exposures through investments in securities and derivatives and short investment exposures substantially through derivatives. A "long" investment exposure is an investment that rises in value with a rise in the value of an asset, asset class or index and declines in value with a decline in the value of that asset, asset class or index. A "short" investment exposure is an investment that rises in value with a decline in the value of an asset, asset class or index and declines in value with a rise in the value of that asset, asset class or index. The value of the Fund's long and short investment exposures may, at times, each reach 100% of the assets invested in the Fund (excluding instruments primarily used for duration management or yield curve management and short-term investments (such as cash and money market instruments)), although these exposures may be higher or lower at any given time.

Fixed-Income Investments. In connection with its principal investment strategies, the Fund may invest in a broad range of U.S. and non-U.S. fixed-income securities, including, but not limited to, corporate bonds, municipal securities, U.S. and non-U.S. government securities (including their agencies, instrumentalities and sponsored entities), securities of supranational entities, emerging market securities, commercial and residential mortgage-backed securities, collateralized mortgage obligations, other mortgage-related securities (such as adjustable rate mortgage securities), asset-backed securities, bank loans, convertible bonds, securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities"), real estate investment trusts ("REITs"), zero-coupon securities, step coupon securities, pay-in-kind ("PIK") securities, inflation-linked bonds, variable and floating rate securities, private placements and commercial paper.

Non-U.S. Currency Investments. Under normal market conditions, the Fund may engage in a broad range of transactions involving non-U.S. and emerging market currencies, including, but not limited to, purchasing and selling forward currency exchange contracts in non-U.S. or emerging market currencies, investing in non-U.S. currency futures contracts, investing in options on non-U.S. currencies and non-U.S. currency futures, investing in cross-currency instruments (such as swaps), investing directly in non-U.S. currencies and investing in securities denominated in non-U.S. currencies. The Fund may engage in non-U.S. currency transactions for investment or for hedging purposes.

Derivative Investments. For investment and hedging purposes, the Fund may invest substantially in a broad range of derivatives instruments and sometimes the majority of its investment returns will derive from its derivative investments. These derivative instruments include, but are not limited to, futures contracts (such as treasury futures and index futures), forward contracts, options (such as options on futures contracts, options on securities, interest rate/bond options, currency options, options on swaps and over-the-counter ("OTC") options), warrants (such as non-U.S. currency warrants) and swap transactions (such as interest rate swaps, total return swaps and index swaps). In addition, the Fund may invest in credit derivative products that may be used to manage default risk and credit exposure. Examples of such products include, but are not limited to, credit default swap index products (such as LCDX, CMBX and ABX index products), single name credit default swaps, loan credit default swaps and asset-backed credit default swaps. The Fund may, at times, invest substantially all of its assets in derivatives and securities used to support its obligations under those derivatives. The Fund's strategy may be highly dependent on the use of derivatives, and to the extent that they become unavailable or unattractive the Fund may be unable to fully implement its investment strategy.

Equity Investments. In connection with its principal investment strategies, the Fund may invest in preferred stocks and convertible preferred stocks. The Fund is non-diversified, which means it may invest a greater portion of its assets in a particular issuer and may invest in fewer issuers. Because the Fund may invest in the securities of fewer issuers, an investment in the Fund may involve a higher degree of risk than would be present in a diversified portfolio.

The Fund expects to 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 return, and realization of greater short-term capital gains, distributions of which are taxable as ordinary income to taxable shareholders. Trading costs and tax effects associated with frequent trading may adversely affect the Fund's performance.

The percentage limitations set forth herein are not investment restrictions and the Fund may exceed these limits from time to time. In addition, when calculating these exposures, the Fund may use the market value, the notional value, an adjusted notional value or some other measure of the value of a derivative in order to reflect what the Adviser believes to be the most accurate assessment of the Fund's real economic exposure. The total notional value of the Fund's derivative instruments may significantly exceed the total value of the Fund's assets.

Although the Fund seeks positive total returns over time, the Fund's investment returns may be volatile over short periods of time. The Fund may outperform the overall securities market during periods of flat or negative performance and may underperform during periods of strong market performance. There can be no assurance that the Fund's returns over time or during any period will be positive.

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.

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

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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 over-the-counter ("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.

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 a significant portion of its assets in currency-related instruments and may invest in securities or other instruments denominated in, or that generate income denominated in, foreign currencies. The Advisor 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.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest, including futures contracts, forward contracts, options, warrants 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, such as futures, forward contracts, options, warrants, foreign currency transactions, swaps and credit default swaps, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward contracts, swaps and other OTC derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate as expected with changes in the value of relevant assets, rates or indices, liquidity risk, allocation risk and the risk of losing more than 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. There is a risk that the Adviser's use of derivatives, such as futures and forward contracts, to manage the Fund's volatility may be ineffective or may exacerbate losses, for example, if the derivative and the underlying assets decrease in value over time.

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 preferred stocks could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock.

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.

Inflation/Deflation Risk: Inflation risk is the risk that the value of assets or income from investments will be worth less in the future as inflation decreases the present value of future payments. Deflation risk is the risk that prices throughout the economy decline over time (the opposite of inflation). Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund's portfolio. Because the Fund seeks positive returns that exceed the rate of inflation over time, if the portfolio managers' inflation forecasts are incorrect, the Fund may be more severely impacted than other funds.

Interest Rate Risk: Interest rate risk is the risk that the value of the Fund's investments will fall if interest rates rise. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. Interest rate risk generally is greater for funds that invest in fixed-income securities with relatively longer durations than for funds that invest in fixed-income securities with shorter durations. The value of zero-coupon and PIK bonds may be more sensitive to fluctuations in interest rates than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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.

Leverage Risk: Use of derivative instruments may involve leverage. Taking short positions in stocks also results in a form of 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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will 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. The Fund's Adviser will attempt to reduce this risk by implementing various volatility management strategies and techniques. However, there is no guarantee that such strategies and techniques will produce the intended result.

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.

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

Short Exposure Risk: A short exposure through a derivative may present various risks, including credit/counterparty risk and leverage risk. If the value of the asset, asset class or index on which the Fund has obtained a short investment exposure increases, the Fund will incur a loss. Unlike a direct cash investment such as a stock, bond or ETF, where the potential loss is limited to the purchase price, the potential risk of loss from a short exposure is theoretically unlimited. Moreover, there can be no assurance that securities necessary to cover (repurchase in order to close) a short position will be available for purchase.

Risk Nondiversified Status [Text]

rr_RiskNondiversifiedStatus

Non-Diversification Risk: Compared with other mutual funds, the Fund may invest a greater percentage of its assets in a particular issuer and may invest in fewer issuers. Therefore, the Fund may have more risk because changes in the value of a single security or the impact of a single economic, political or regulatory occurrence may have a greater adverse impact on the Fund's net asset value.

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 and Life-of-Fund periods compare to those of two broad measures 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:
First Quarter 2012, 5.54%

Lowest Quarterly Return:
Third Quarter 2011, -4.71%

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.

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 and Life-of-Fund 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

(Loomis Sayles Strategic Alpha Fund) | 3-month London Interbank Offered Rate (LIBOR)

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.66%

Past 5 Years

rr_AverageAnnualReturnYear05

0.38%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.36%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha Fund) | 3-month LIBOR +300 basis points

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

3.73%

Past 5 Years

rr_AverageAnnualReturnYear05

3.44%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

3.42%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha 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

^[9]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

0.60%

^[20]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.15%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.00%

^[21]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[22],[23]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.00%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 523

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

730

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

954

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,598

Past 1 Year

rr_AverageAnnualReturnYear01

2.03%

Past 5 Years

rr_AverageAnnualReturnYear05

3.06%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.92%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha 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

0.60%

^[20]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.15%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.75%

^[21]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[22],[23]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.75%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 278

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

551

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

949

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,062

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

178

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

551

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

949

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,062

Past 1 Year

rr_AverageAnnualReturnYear01

4.70%

Past 5 Years

rr_AverageAnnualReturnYear05

3.17%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.85%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha 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

0.60%

^[20]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.08%

^[19]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.68%

^[21]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[22],[23]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.68%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 69

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

218

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

379

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 847

(Loomis Sayles Strategic Alpha 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

0.60%

^[20]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.15%

^[19]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.00%

^[21]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[22],[23]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.00%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 349

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

560

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

789

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,444

Past 1 Year

rr_AverageAnnualReturnYear01

3.93%

Past 5 Years

rr_AverageAnnualReturnYear05

3.43%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.21%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha 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

0.60%

^[20]

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.15%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.75%

^[21]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[22],[23]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.75%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 77

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

240

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

417

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 930

Annual Return 2011

rr_AnnualReturn2011

(3.78%)

Annual Return 2012

rr_AnnualReturn2012

12.57%

Annual Return 2013

rr_AnnualReturn2013

1.19%

Annual Return 2014

rr_AnnualReturn2014

2.52%

Annual Return 2015

rr_AnnualReturn2015

(1.43%)

Annual Return 2016

rr_AnnualReturn2016

6.86%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2012, 5.54%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.54%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Third Quarter 2011, -4.71%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(4.71%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Past 1 Year

rr_AverageAnnualReturnYear01

6.86%

Past 5 Years

rr_AverageAnnualReturnYear05

4.23%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.90%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

5.77%

Past 5 Years

rr_AverageAnnualReturnYear05

2.96%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.66%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(Loomis Sayles Strategic Alpha Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

3.87%

Past 5 Years

rr_AverageAnnualReturnYear05

2.72%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.72%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 15, 2010

(McDonnell Intermediate Municipal Bond Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

Investment Goal

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks a high level of federal tax-exempt current income, consistent with the preservation of capital.

Expense [Heading]

rr_ExpenseHeading

Fund Fees & Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

The following table describes the fees and expenses that you may pay if you buy 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 88 of the Prospectus, in Appendix A to the Prospectus and on page 113 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

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

A 0.75% contingent deferred sales charge ("CDSC") may apply to certain purchases of Class A shares of $500,000 or more that are redeemed within eighteen months of the date of purchase.

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 its most recently ended fiscal year, the Fund's portfolio turnover rate was 48% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

48.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus borrowings made for investment purposes) in municipal securities that pay interest exempt from federal income taxes. Municipal securities are debt instruments typically issued by or on behalf of state and local governments, territories or possessions of the United States, including the District of Columbia, and their political subdivisions, agencies and instrumentalities and may include general obligation, revenue and private activity bonds and notes. In addition, the Fund may invest up to 20% of its assets in securities that pay interest subject to federal income taxation. The Fund may invest up to 20% of its assets in debt securities subject to the federal alternative minimum tax. The Fund's investments may include securities issued by the U.S. government, its agencies and instrumentalities and corporate debt securities. The Fund will invest primarily in investment grade fixed-income securities. "Investment grade" securities are those securities that are rated in one of the top four ratings categories at the time of purchase by at least one of the three major ratings agencies (Moody's Investors Service, Inc., Fitch Investors Services, Inc. or S&P Global Ratings), or, if unrated, are determined by McDonnell Investment Management, LLC ("McDonnell" or the "Subadviser") to be of comparable quality. The Subadviser considers pre-refunded bonds and municipal securities escrowed to maturity using U.S. Treasury securities or U.S. government agency securities to be investment grade securities, regardless of rating. The Fund may also invest up to 10% of its assets in securities that are not investment grade (commonly known as "junk bonds"). Under normal circumstances, the dollar-weighted average maturity of the Fund's portfolio is expected to be between 3 and 10 years although the Fund may invest in securities of any maturity.

The portfolio management team seeks to build a portfolio based on a number of factors including sector, duration and maturity distribution, yield, expected return, credit momentum outlook (sector and security level), credit quality, security structure, issue size and liquidity. Through the use of quantitative and fundamental analysis, the pool of possible portfolio investments is screened using these factors to arrive at a narrower universe of securities that the Subadviser believes are suitable for the Fund's portfolio. Potential investments are also subject to a portfolio risk assessment that may include the following:

• Determining the ability of creditors to fully repay debt obligations in a timely manner.

• Use of a wide variety of internal and external quantitative and analytical and informational sources to assess likelihood of repayment.

• Monitoring rating agency and third party surveillance sources with an emphasis on core holdings.

The Subadviser may sell a security for a variety of reasons, including duration management, yield curve positioning, sector rotation, a change in credit momentum outlook or if more attractive investment opportunities are identified.

The Fund may also:

• Invest in when-issued securities and securities issued pursuant to Rule 144A under the Securities Act of 1933 ("Rule 144A securities").

• Enter into futures transactions for hedging and investment purposes.

• Invest in other investment companies to the extent permitted by the Investment Company Act of 1940.

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.

Below Investment Grade Fixed-Income Securities Risk: The Fund's investments in below investment grade fixed-income securities, also known as "junk bonds," may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit/counterparty risk (including a greater risk of default) and liquidity risk. The ability of the issuer to make principal and interest payments is predominantly speculative for below investment grade fixed-income securities.

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.

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, such as options, foreign currency transactions, futures transactions, and swap transactions, involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for over-the-counter 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.

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 market for these securities and reduce the Fund's ability to sell them, negatively impacting the performance of the Fund.

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

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. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. 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.

Municipal Securities Risk: Municipal bonds are investments issued by states, cities, public authorities or political subdivisions to raise money for public purposes, including general obligation bonds and revenue obligations. Municipal securities are subject to information risk, liquidity risk, credit risk and the risks that economic, political, fiscal or regulatory events, legislative changes and the enforceability of rights of municipal bond holders could adversely affect the values of municipal bonds. Municipal obligations may be susceptible to downgrades or defaults during recessions or similar periods of economic stress and insolvent municipalities may file for bankruptcy, which could significantly affect the rights of creditors and the value of the municipal securities. In addition, if the municipal securities held by the Fund fail to meet certain legal requirements allowing interest distributed from such securities to be tax-exempt, the interest received and distributed to shareholders by the Fund may be taxable.

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 and Life-of-Fund periods compare to two broad measures 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:
Second Quarter 2016, 2.21%

Lowest Quarterly Return:
Fourth Quarter 2016, -3.76%

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 T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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 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. The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. 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 shares through tax-advantaged arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the one year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period.

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 and Life-of-Fund periods compare to 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

(McDonnell Intermediate Municipal Bond Fund) | Bloomberg Barclays Municipal Bond Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.25%

^[24]

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.42%

^[24]

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

^[24]

(McDonnell Intermediate Municipal Bond Fund) | Bloomberg Barclays 3-15 Year Blend Municipal Bond Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(0.05%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

2.14%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond Fund) | Class A

Prospectus:

rr_ProspectusTable

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

3.00%

Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)

rr_MaximumDeferredSalesChargeOverOther

none

^[25]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.88%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[26]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 369

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

555

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

756

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,336

Past 1 Year

rr_AverageAnnualReturnYear01

(3.75%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.40%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond 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

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.63%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[26]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 248

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

497

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

870

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,918

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

148

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

497

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

870

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,918

Past 1 Year

rr_AverageAnnualReturnYear01

(2.42%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.45%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond 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

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.23%

^[12]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.88%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[26]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 320

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

505

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

707

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,290

Past 1 Year

rr_AverageAnnualReturnYear01

(3.29%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

0.54%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond 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

0.40%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.63%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.18%

^[26]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.45%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 46

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

184

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

333

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 769

Annual Return 2013

rr_AnnualReturn2013

(2.31%)

Annual Return 2014

rr_AnnualReturn2014

6.36%

Annual Return 2015

rr_AnnualReturn2015

2.63%

Annual Return 2016

rr_AnnualReturn2016

(0.55%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Second Quarter 2016, 2.21%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

2.21%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2016

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Fourth Quarter 2016, -3.76%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.76%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2016

Past 1 Year

rr_AverageAnnualReturnYear01

(0.55%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.48%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(0.55%)

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.48%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(McDonnell Intermediate Municipal Bond Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.33%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

1.47%

Inception Date

rr_AverageAnnualReturnInceptionDate

Dec. 31, 2012

(Natixis Oakmark 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

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 16% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

16.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund primarily invests in common stocks of U.S. companies. The Fund generally invests in securities of larger capitalization companies in any industry. Harris Associates L.P. ("Harris Associates") uses a value investment philosophy in selecting equity securities, including common stocks. This philosophy is based upon the belief that, over time, a company's stock price converges with 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 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' estimate of 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 60 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.

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.

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.

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 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:
Second Quarter 2009, 24.26%

Lowest Quarterly Return:
Fourth Quarter 2008, -26.95%

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

(Natixis Oakmark 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 Oakmark 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

^[27]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

0.69%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.18%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[28],[29]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 688

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

928

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,187

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,924

Past 1 Year

rr_AverageAnnualReturnYear01

11.55%

Past 5 Years

rr_AverageAnnualReturnYear05

13.69%

Past 10 Years

rr_AverageAnnualReturnYear10

5.81%

(Natixis Oakmark 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

0.69%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.24%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.93%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[28],[29]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.93%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 296

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

606

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,042

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,254

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

196

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

606

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,042

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,254

Past 1 Year

rr_AverageAnnualReturnYear01

16.45%

Past 5 Years

rr_AverageAnnualReturnYear05

14.19%

Past 10 Years

rr_AverageAnnualReturnYear10

5.65%

(Natixis Oakmark 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

0.69%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.12%

^[30]

Total annual fund operating expenses

rr_ExpensesOverAssets

0.81%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[28],[29]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.81%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 83

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

259

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

450

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,002

(Natixis Oakmark 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

0.69%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.24%

^[30]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.18%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[28],[29]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.18%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 367

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

615

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

883

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,646

Past 1 Year

rr_AverageAnnualReturnYear01

15.43%

Past 5 Years

rr_AverageAnnualReturnYear05

14.46%

Past 10 Years

rr_AverageAnnualReturnYear10

6.18%

(Natixis Oakmark 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

0.69%

Distribution and/or service (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.23%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.92%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[28],[29]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

0.92%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 94

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

293

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

509

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,131

Annual Return 2007

rr_AnnualReturn2007

(2.59%)

Annual Return 2008

rr_AnnualReturn2008

(40.18%)

Annual Return 2009

rr_AnnualReturn2009

44.39%

Annual Return 2010

rr_AnnualReturn2010

13.47%

Annual Return 2011

rr_AnnualReturn2011

(1.40%)

Annual Return 2012

rr_AnnualReturn2012

17.33%

Annual Return 2013

rr_AnnualReturn2013

38.21%

Annual Return 2014

rr_AnnualReturn2014

10.70%

Annual Return 2015

rr_AnnualReturn2015

(4.18%)

Annual Return 2016

rr_AnnualReturn2016

18.69%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Second Quarter 2009, 24.26%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

24.26%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Jun. 30, 2009

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Fourth Quarter 2008, -26.95%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(26.95%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2008

Past 1 Year

rr_AverageAnnualReturnYear01

18.69%

Past 5 Years

rr_AverageAnnualReturnYear05

15.34%

Past 10 Years

rr_AverageAnnualReturnYear10

6.75%

(Natixis Oakmark Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

17.56%

Past 5 Years

rr_AverageAnnualReturnYear05

13.89%

Past 10 Years

rr_AverageAnnualReturnYear10

6.00%

(Natixis Oakmark Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

11.35%

Past 5 Years

rr_AverageAnnualReturnYear05

12.19%

Past 10 Years

rr_AverageAnnualReturnYear10

5.35%

(Vaughan Nelson Value Opportunity 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

Other Expenses, New Fund, Based on Estimates [Text]

rr_OtherExpensesNewFundBasedOnEstimates

Other expenses are estimated for the current fiscal year.

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 57% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

57.00%

Strategy [Heading]

rr_StrategyHeading

Investments, Risks and Performance

Principal Investment Strategies

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

Under normal market conditions, the Fund will invest primarily in companies that, at the time of purchase, have market capitalizations either within the capitalization range of the Russell Midcap® Value Index, an unmanaged index that measures the performance of companies with lower price-to-book ratios and lower forecasted growth values within the broader Russell Midcap® Index, or of $15 billion or less. While the market capitalization range for the Russell Midcap® Value Index fluctuates, at December 31, 2016, it was $454.2 million to $38.8 billion. However, the Fund does not have any market capitalization limits and may invest in companies with smaller or larger capitalizations. 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 similar securities.

Vaughan Nelson Investment Management, L.P. ("Vaughan Nelson") invests in medium-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:

• Vaughan Nelson employs a value-driven investment philosophy that selects stocks selling at a relatively low value based on business fundamentals, economic margin analysis and discounted cash flow models. Vaughan Nelson selects companies that it believes are out of favor or misunderstood.

• Vaughan Nelson narrows the investment universe by using value-driven screens to create a research universe of companies with market capitalizations between $1 billion and $20 billion.

• Vaughan Nelson uses fundamental analysis to construct a portfolio 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 markets securities.

• Invest in other investment companies, to the extent permitted by the Investment Company Act of 1940.

• Invest in REITs.

• 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").

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. Rule 144A securities may be less liquid than other equity securities. 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.

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

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. 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, life-of-fund 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 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, 21.36%

Lowest Quarterly Return:
Third Quarter 2011, -21.12%

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 did not have Class T shares outstanding during the periods shown above. The returns of Class T shares would have been substantially similar to the returns of the Fund's other share classes because they would have been invested in the same portfolio of securities and would only differ to the extent the other share classes did not have the same expenses. Performance of Class T shares shown above is that of Class A shares, which have the same expenses as Class T shares, restated to reflect the different sales load applicable to Class T shares. 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, life-of-fund 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

(Vaughan Nelson Value Opportunity Fund) | Russell Midcap® Value Index

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

20.00%

Past 5 Years

rr_AverageAnnualReturnYear05

15.70%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

15.44%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity Fund) | Russell Midcap® Value Index (5/1/13)

Prospectus:

rr_ProspectusTable

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.38%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 01, 2013

(Vaughan Nelson Value Opportunity 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

^[27]

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

0.18%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.25%

^[31]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.48%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[32]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.48%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 717

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

1,016

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,336

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,242

Past 1 Year

rr_AverageAnnualReturnYear01

(0.22%)

Past 5 Years

rr_AverageAnnualReturnYear05

11.79%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.20%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity 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

0.18%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.25%

^[31]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.23%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[32]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

2.23%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 326

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

697

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,195

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,565

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

226

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

697

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,195

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,565

Past 1 Year

rr_AverageAnnualReturnYear01

4.03%

Past 5 Years

rr_AverageAnnualReturnYear05

12.27%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.18%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity 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

0.08%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.25%

^[31]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.13%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[32]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.13%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 115

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

359

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

622

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,375

Past 1 Year

rr_AverageAnnualReturnYear01

6.21%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

10.11%

Inception Date

rr_AverageAnnualReturnInceptionDate

May 01, 2013

(Vaughan Nelson Value Opportunity 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

0.18%

^[30]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.25%

^[31]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.48%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[32]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.48%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 397

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

706

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,038

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,974

Past 1 Year

rr_AverageAnnualReturnYear01

3.22%

Past 5 Years

rr_AverageAnnualReturnYear05

12.55%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.67%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity 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

0.18%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.25%

^[31]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.23%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[32]

Total annual fund operating expenses after fee waiver and/or expense reimbursement

rr_NetExpensesOverAssets

1.23%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 125

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

390

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

676

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,489

Annual Return 2009

rr_AnnualReturn2009

31.37%

Annual Return 2010

rr_AnnualReturn2010

19.96%

Annual Return 2011

rr_AnnualReturn2011

(2.53%)

Annual Return 2012

rr_AnnualReturn2012

16.28%

Annual Return 2013

rr_AnnualReturn2013

41.52%

Annual Return 2014

rr_AnnualReturn2014

11.23%

Annual Return 2015

rr_AnnualReturn2015

(3.47%)

Annual Return 2016

rr_AnnualReturn2016

6.14%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: Third Quarter 2009, 21.36%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

21.36%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Third Quarter 2011, -21.12%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(21.12%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Sep. 30, 2011

Past 1 Year

rr_AverageAnnualReturnYear01

6.14%

Past 5 Years

rr_AverageAnnualReturnYear05

13.40%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

13.30%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity Fund) | Class Y | Return After Taxes on Distributions

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

5.26%

Past 5 Years

rr_AverageAnnualReturnYear05

12.21%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

12.40%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

(Vaughan Nelson Value Opportunity Fund) | Class Y | Return After Taxes on Distributions and Sale of Fund Shares

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

4.11%

Past 5 Years

rr_AverageAnnualReturnYear05

10.63%

Average Annual Return Since Inception

rr_AverageAnnualReturnSinceInception

10.89%

Inception Date

rr_AverageAnnualReturnInceptionDate

Oct. 31, 2008

[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] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.10%, 1.85%, 0.80%, 1.10% and 0.85% 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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Fund's 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 fee/expense was waived/reimbursed.

[3] NGAM Advisors, L.P. ("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 March 31, 2018 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[4] Other expenses are estimated for the current fiscal year.

[5] 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.

[6] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.30%, 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 March 31, 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 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.

[7] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.05%, 1.80%, 0.75%, 1.05% and 0.80% 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 March 31, 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 limitations for Class A, C, N, T and Y shares. The Fund will not be obligated to repay any such waived/reimbursed fees or expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

[8] NGAM Advisors, L.P. ("NGAM Advisors") 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, dividend expenses on securities sold short, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through March 31, 2019 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.

[9] 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.

[10] 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.

[11] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.15%, 1.90%, 1.15% and 0.90% of the Fund's average daily net assets for Class A, Class C, Class T and Class Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational expenses 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[12] Other expenses are estimated for the current fiscal year.

[13] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%; the ratios 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.

[14] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.54%, 2.29%, 1.24%, 1.54% and 1.29% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class N, Class T and Class 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 fee/expense was waived/reimbursed.

[15] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.70%, 2.45%, 1.40%, 1.70% and 1.45% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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 1.70%, 2.45%, 1.40%, 1.70% and 1.45% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class Y shares, respectively. 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 fee/expense was waived/reimbursed.

[16] 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.

[17] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%.

[18] AlphaSimplex Group, LLC ("AlphaSimplex" 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 1.24%, 1.99%, 1.24% and 0.99% of the Fund's average daily net assets for Class A, Class C, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[19] Other expenses are estimated for the current fiscal year.

[20] The Fund's operating expenses have been restated to reflect a reduction in management fees, effective as of July 1, 2017, as if such reduction had been in effect during the fiscal year ended December 31, 2016. The information has been restated to better reflect anticipated expenses of the Fund.

[21] The expense information shown in the table above includes acquired fund fees and expenses of less than 0.01%.

[22] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.00%, 1.75%, 0.70%, 1.00% and 0.75% of the Fund's average daily net assets for Class A, Class C, Class N, Class T and Class 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, 2019 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 limitations for Class A, Class C, Class N, Class T and Class 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 fee/expense was waived/reimbursed.

[23] 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.

[24] Effective May 22, 2017, the Bloomberg Barclays Municipal Bond Index replaced the Bloomberg Barclays 3-15 Year Blend Municipal Bond Index as the Fund's primary benchmark because the Fund believes the Bloomberg Barclays Municipal Bond Index, an index which covers the U.S. dollar-denominated long-term tax exempt bond market, is a more appropriate comparison to the Fund's investment strategies. It is not possible to invest directly in an index.

[25] A 0.75% contingent deferred sales charge ("CDSC") may apply to certain purchases of Class A shares of $500,000 or more that are redeemed within eighteen months of the date of purchase.

[26] 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 0.70%, 1.45%, 0.70% and 0.45% of the Fund's average daily net assets for Class A, Class C, Class T and Class 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 limitations for Class A, Class C, Class T and Class 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 fee/expense was waived/reimbursed.

[27] 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.

[28] 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.

[29] 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 1.30%, 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 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.

[30] Other expenses are estimated for the current fiscal year.

[31] 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.

[32] 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 1.40%, 2.15%, 1.10%, 1.40% and 1.15% 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.