485BPOS

Registration Nos. 2-11101

811-00242

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM N-1A

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933	☐
Pre-Effective Amendment No.	☐
Post-Effective Amendment No. 224	☒

and/or

REGISTRATION STATEMENT UNDER THE INVESTMENT COMPANY ACT OF 1940	☐
Amendment No. 152	☒
(Check appropriate box or boxes.)

NATIXIS FUNDS TRUST II

(Exact Name of Registrant as Specified in Charter)

888 Boylston Street, Boston, Massachusetts 02199

(Address of principal executive offices) (Zip Code)

Registrant’s Telephone Number, including Area Code (617) 449-2822

Russell Kane, Esq.

Natixis Distribution, L.P.

888 Boylston Street

Boston, Massachusetts 02199

(Name and Address of Agent for Service)

Copy to:

John M. Loder, Esq.

Ropes & Gray

800 Boylston Street

Boston, Massachusetts 02119

Approximate Date of Proposed Public Offering

It is proposed that this filing will become effective (check appropriate box):

☒ immediately upon filing pursuant to paragraph (b)

☐ on (date) pursuant to paragraph (b)

☐ 60 days after filing pursuant to paragraph (a)(1)

☐ on (date) pursuant to paragraph (a)(1)

☐ 75 days after filing pursuant to paragraph (a)(2)

☐ on (date) pursuant to paragraph (a)(2) of Rule 485.

If appropriate, check the following box:

☐ This post-effective amendment designates a new effective date for a previously filed post-effective amendment.

NATIXIS FUNDS TRUST II

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, as amended, and the Investment Company Act of 1940, as amended, the Registrant certifies that it meets all of the requirements for effectiveness of this Post-Effective Amendment to its Registration Statement under Rule 485(b) under the Securities Act of 1933, as amended, and has duly caused this Post-Effective Amendment to its Registration Statement to be signed on its behalf by the undersigned, duly authorized, in the City of Boston, and the Commonwealth of Massachusetts on the 17^th day of April, 2019.

NATIXIS FUNDS TRUST II
By:	/s/ David L Giunta
	David L. Giunta
	President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, as amended, this amendment to the Registration Statement has been signed below by the following persons in the capacities and on the date indicated.

Signature	Title	Date
/s/ David L Giunta David L. Giunta	President, Chief Executive Officer	April 17, 2019
	and Trustee
/s/ Michael C. Kardok Michael C. Kardok	Treasurer	April 17, 2019
Kevin P. Charleston* Kevin P. Charleston	Trustee	April 17, 2019
Kenneth A. Drucker* Kenneth A. Drucker	Trustee, Chairperson of the Board	April 17, 2019
Edmond J. English* Edmond J. English	Trustee	April 17, 2019
Richard A. Goglia* Richard A. Goglia	Trustee	April 17, 2019
Wendell J. Knox* Wendell J. Knox	Trustee	April 17, 2019
Martin T. Meehan* Martin T. Meehan	Trustee	April 17, 2019
Maureen B. Mitchell * Maureen B. Mitchell	Trustee	April 17, 2019

James P. Palermo* James P. Palermo	Trustee	April 17, 2019
Erik R. Sirri* Erik R. Sirri	Trustee	April 17, 2019
Peter J. Smail* Peter J. Smail	Trustee	April 17, 2019
Cynthia L. Walker* Cynthia L. Walker	Trustee	April 17, 2019

*By:	/s/ Russell Kane
	Russell Kane
	Attorney-In-Fact 1
	April 17, 2019

¹  Powers of Attorney for Kevin P. Charleston, Kenneth A. Drucker, Edmond J. English, David L. Giunta, Richard A. Goglia, Wendell J. Knox, Martin T. Meehan, Maureen B. Mitchell, James P. Palermo, Erik R. Sirri, Peter J. Smail and Cynthia L. Walker dated December 5, 2018, effective December 10, 2018, designating John M. Loder, Russell Kane, Kirk Johnson and Michael Kardok as attorneys to sign for each Trustee is incorporated by reference to exhibit (p)(1) to PEA No. 222 to the Registration Statement filed on February 28, 2019.

Natixis Funds Trust II

Exhibit Index

Exhibits for Item 28 of Form N-1A

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	485BPOS
Document Period End Date	dei_DocumentPeriodEndDate	Nov. 30, 2018
Registrant Name	dei_EntityRegistrantName	Natixis Funds Trust II
Central Index Key	dei_EntityCentralIndexKey	0000052136
Amendment Flag	dei_AmendmentFlag	false
Document Creation Date	dei_DocumentCreationDate	Mar. 29, 2019
Document Effective Date	dei_DocumentEffectiveDate	Apr. 01, 2019
Prospectus Date	rr_ProspectusDate	Apr. 01, 2019

XML

(Loomis Sayles Global Growth Fund)

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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").

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

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]	0.52%	0.52%	0.50%	0.52%	[2]	0.52%
Total annual fund operating expenses		1.57%	2.32%	1.30%	1.57%		1.32%
Fee waiver and/or expense reimbursement	[3],[4]	0.27%	0.27%	0.30%	0.27%		0.27%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.30%	2.05%	1.00%	1.30%		1.05%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example - (Loomis Sayles Global Growth Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	700	1,017	1,357	2,313
Class C	308	699	1,216	2,635
Class N	107	392	698	1,567
Class T	379	708	1,059	2,048
Class Y	102	382	684	1,541

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

Expense Example, No Redemption - (Loomis Sayles Global Growth Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	208	699	1,216	2,635

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 24% of the average value of its portfolio.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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, when a critical underlying investment assumption is flawed, when a more attractive reward-to-risk opportunity becomes available, when the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate.

The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in 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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 involves other risks, 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. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund's investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Large Investor Risk: Ownership of shares of the Fund may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund's expenses.

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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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, life-of-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

Highest Quarterly Return:
First Quarter 2017, 8.79%

Lowest Quarterly Return:
Fourth Quarter 2018, -12.53%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

Average Annual Total Returns - (Loomis Sayles Global Growth Fund)	Past 1 Year	Life of Class N / Life of Fund	Inception Date
Class Y	(6.71%)	10.19%	Mar. 31, 2016
Class Y | Return After Taxes on Distributions	(7.70%)	9.10%	Mar. 31, 2016
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	(3.24%)	7.79%	Mar. 31, 2016
Class A	(12.27%)	7.58%	Mar. 31, 2016
Class C	(8.52%)	9.06%	Mar. 31, 2016
Class N	(6.66%)	7.37%	Mar. 31, 2017
Class T	(9.29%)	8.90%	Mar. 31, 2016
MSCI ACWI Index (Net)	(9.41%)	7.12%	Mar. 31, 2016
MSCI ACWI Index (Net) (3/31/17)		2.85%	Mar. 31, 2017

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 Return After Taxes on Distributions and Sale of Fund Shares for the 1-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. 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 Senior Floating Rate and Fixed Income Fund)

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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").

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

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		0.20%	0.20%	0.35%	0.20%	[1]	0.20%
Total annual fund operating expenses		1.05%	1.80%	0.95%	1.05%		0.80%
Fee waiver and/or expense reimbursement	[2],[3]	none	none	0.21%	none		none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.05%	1.80%	0.74%	1.05%		0.80%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example - (Loomis Sayles Senior Floating Rate and Fixed Income Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	453	672	909	1,588
Class C	283	566	975	2,116
Class N	76	282	505	1,147
Class T	354	576	815	1,501
Class Y	82	255	444	990

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

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	566	975	2,116

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 65% of the average value of its portfolio.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 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 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. Potential future changes in government monetary policy may affect the level of interest rates, and the current historically low interest rate environment, combined with the Federal Reserve Board's conclusion of its quantitative easing program and recent increases in interest rates, increases the likelihood of interest rates rising in the future.

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 invests 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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

Highest Quarterly Return:
First Quarter 2012, 5.09%

Lowest Quarterly Return:
Fourth Quarter 2018, -3.02%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

Average Annual Total Returns - (Loomis Sayles Senior Floating Rate and Fixed Income Fund)	Past 1 Year	Past 5 Years	Life of Class N / Life of Fund	Inception Date
Class Y	0.39%	3.56%	5.53%	Sep. 30, 2011
Class Y | Return After Taxes on Distributions	(1.95%)	0.97%	2.93%	Sep. 30, 2011
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	0.26%	1.54%	3.13%	Sep. 30, 2011
Class A	(3.47%)	2.55%	4.75%	Sep. 30, 2011
Class C	(1.65%)	2.52%	4.49%	Sep. 30, 2011
Class N	0.45%		2.36%	Mar. 31, 2017
Class T	(2.43%)	2.76%	4.90%	Sep. 30, 2011
S&P / LSTA Leveraged Loan Index	0.44%	3.05%	4.55%	Sep. 30, 2011
S&P / LSTA Leveraged Loan Index (3/31/17)			1.92%	Mar. 31, 2017

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.

(Vaughan Nelson Select Fund)

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

The Fund seeks long-term capital appreciation.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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").

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

Annual Fund Operating Expenses - (Vaughan Nelson Select Fund)		Class A	Class C	Class N	Class T		Class Y
Management fees	[1]	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		0.22%	0.21%	12.74%	0.22%	[2]	0.21%
Acquired fund fees and expenses	[3]	0.09%	0.09%	0.09%	0.09%		0.09%
Total annual fund operating expenses	[4],[5]	1.36%	2.10%	13.63%	1.36%		1.10%
Fee waiver and/or expense reimbursement		0.07%	0.06%	12.64%	0.07%		0.06%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.29%	2.04%	0.99%	1.29%		1.04%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

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:

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example - (Vaughan Nelson Select Fund) - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	699	974	1,271	2,110
Class C	307	652	1,123	2,426
Class N	101	2,694	4,862	8,842
Class T	378	663	970	1,838
Class Y	106	344	600	1,335

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

Expense Example, No Redemption - (Vaughan Nelson Select Fund)	1 Year	3 Years	5 Years	10 Years
Class C | USD ($)	207	652	1,123	2,426

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 54% of the average value of its portfolio.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 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.

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. Potential future changes in government monetary policy may affect the level of interest rates, and the current historically low interest rate environment, combined with the Federal Reserve Board's conclusion of its quantitative easing program and recent increases in interest rates, increases the likelihood of interest rates rising in the future.

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 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 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.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

Highest Quarterly Return:
First Quarter 2013, 12.67%

Lowest Quarterly Return:
Fourth Quarter 2018, -15.44%

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

Average Annual Total Returns - (Vaughan Nelson Select Fund)	Past 1 Year	Past 5 Years	Life of Class N / Life of Fund	Inception Date
Class Y	(4.56%)	7.55%	12.84%	Jun. 29, 2012
Class Y | Return After Taxes on Distributions	(6.80%)	6.27%	10.99%	Jun. 29, 2012
Class Y | Return After Taxes on Distributions and Sale of Fund Shares	(1.18%)	5.87%	9.93%	Jun. 29, 2012
Class A	(10.25%)	6.01%	11.54%	Jun. 29, 2012
Class C	(6.33%)	6.48%	11.73%	Jun. 29, 2012
Class N	(4.62%)		5.85%	Mar. 31, 2017
Class T	(7.16%)	6.74%	12.11%	Jun. 29, 2012
S&P 500® Index	(4.38%)	8.49%	12.16%	Jun. 29, 2012
S&P 500® Index (3/31/17)			5.50%	Mar. 31, 2017

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 Return After Taxes on Distributions and Sale of Fund Shares for the 1-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. 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 have been restated to reflect current custodian fees for the Fund effective October 1, 2018.

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

[3] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 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, 2020 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.

[4] Natixis Advisors, L.P. ("Natixis Advisors") has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2020 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, 2020 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] Natixis Advisors, L.P. ("Natixis Advisors") has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2020 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] Management fees have been restated to reflect the current management fees for the Fund effective as of July 1, 2018.

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

[3] 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.

[4] Natixis Advisors has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2020 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[5] Natixis Advisors, L.P. ("Natixis Advisors") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.20%, 1.95%, 0.90%, 1.20% and 0.95% 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, 2020 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 Global Growth Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

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<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

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

Expense [Heading]

rr_ExpenseHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

March 31, 2020

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 24% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

24.00%

Strategy [Heading]

rr_StrategyHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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, when a critical underlying investment assumption is flawed, when a more attractive reward-to-risk opportunity becomes available, when the current price fully reflects intrinsic value, or for other investment reasons which the portfolio manager deems appropriate.

The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in 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]

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<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 involves other risks, 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. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer's bonds generally take precedence over the claims of those who own preferred stock or common stock.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit/counterparty and information risks. The Fund's investments in foreign securities also are subject to foreign currency fluctuations and other foreign currency-related risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Large Investor Risk: Ownership of shares of the Fund may be concentrated in one or a few large investors. Such investors may redeem shares in large quantities or on a frequent basis. Redemptions by a large investor can affect the performance of the Fund, may increase realized capital gains, including short-term capital gains taxable as ordinary income, may accelerate the realization of taxable income to shareholders and may increase transaction costs. These transactions potentially limit the use of any capital loss carryforwards and certain other losses to offset future realized capital gains (if any). Such transactions may also increase the Fund's expenses.

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]

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<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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, life-of-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Bar Chart [Heading]

rr_BarChartHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

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 2017, 8.79%

Lowest Quarterly Return:
Fourth Quarter 2018, -12.53%

Performance Table Heading

rr_PerformanceTableHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

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 Return After Taxes on Distributions and Sale of Fund Shares for the 1-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. 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 Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the 1-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, life-of-class and life-of-fund 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. After-tax returns for the other classes of the Fund will vary.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

im.natixis.com

Performance Availability Phone [Text]

rr_PerformanceAvailabilityPhone

800-225-5478

(Loomis Sayles Global Growth Fund) | MSCI ACWI Index (Net)

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(9.41%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

7.12%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

(Loomis Sayles Global Growth Fund) | MSCI ACWI Index (Net) (3/31/17)

Prospectus:

rr_ProspectusTable

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

2.85%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

^[1]

Redemption fees

rr_RedemptionFee

none

Management fees

rr_ManagementFeesOverAssets

0.80%

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

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.52%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.57%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.27%

^[3],[4]

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

1,017

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,357

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,313

Past 1 Year

rr_AverageAnnualReturnYear01

(12.27%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

7.58%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

(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

0.52%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.32%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.27%

^[3],[4]

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

699

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,216

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,635

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

208

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

699

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,216

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,635

Past 1 Year

rr_AverageAnnualReturnYear01

(8.52%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

9.06%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

(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

0.50%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.30%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.30%

^[3],[4]

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

rr_NetExpensesOverAssets

1.00%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 107

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

392

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

698

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,567

Past 1 Year

rr_AverageAnnualReturnYear01

(6.66%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

7.37%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

0.52%

^[2],[5]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.57%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.27%

^[3],[4]

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

708

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,059

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,048

Past 1 Year

rr_AverageAnnualReturnYear01

(9.29%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

8.90%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

(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

0.52%

^[2]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.32%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.27%

^[3],[4]

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

rr_NetExpensesOverAssets

1.05%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 102

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

382

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

684

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,541

Annual Return 2017

rr_AnnualReturn2017

32.00%

Annual Return 2018

rr_AnnualReturn2018

(6.71%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2017, 8.79%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.79%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2017

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Fourth Quarter 2018, -12.53%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(12.53%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Past 1 Year

rr_AverageAnnualReturnYear01

(6.71%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

10.19%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(7.70%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

9.10%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(3.24%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

7.79%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2016

(Loomis Sayles Senior Floating Rate and Fixed Income Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

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

Expense [Heading]

rr_ExpenseHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

March 31, 2020

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund's operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement assuming that such waiver and/or reimbursement will only be in place through the dates noted above and on the Total Annual Fund Operating Expenses for the remaining periods. 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 65% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

65.00%

Strategy [Heading]

rr_StrategyHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 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 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. Potential future changes in government monetary policy may affect the level of interest rates, and the current historically low interest rate environment, combined with the Federal Reserve Board's conclusion of its quantitative easing program and recent increases in interest rates, increases the likelihood of interest rates rising in the future.

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 invests 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Bar Chart [Heading]

rr_BarChartHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

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, 5.09%

Lowest Quarterly Return:
Fourth Quarter 2018, -3.02%

Performance Table Heading

rr_PerformanceTableHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

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 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-class and life-of-fund 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. After-tax returns for the other classes of the Fund will vary.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

im.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

0.44%

Past 5 Years

rr_AverageAnnualReturnYear05

3.05%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

4.55%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Loomis Sayles Senior Floating Rate and Fixed Income Fund) | S&P / LSTA Leveraged Loan Index (3/31/17)

Prospectus:

rr_ProspectusTable

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

1.92%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

0.20%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.05%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[4],[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

$ 453

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

672

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

909

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,588

Past 1 Year

rr_AverageAnnualReturnYear01

(3.47%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.55%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

4.75%

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

0.20%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.80%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[4],[6]

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

566

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

975

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,116

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

183

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

566

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

975

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,116

Past 1 Year

rr_AverageAnnualReturnYear01

(1.65%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.52%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

4.49%

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

0.35%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.95%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.21%

^[4],[6]

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

rr_NetExpensesOverAssets

0.74%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 76

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

282

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

505

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,147

Past 1 Year

rr_AverageAnnualReturnYear01

0.45%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

2.36%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

0.20%

^[5]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.05%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[4],[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

$ 354

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

576

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

815

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,501

Past 1 Year

rr_AverageAnnualReturnYear01

(2.43%)

Past 5 Years

rr_AverageAnnualReturnYear05

2.76%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

4.90%

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

0.20%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.80%

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

none

^[4],[6]

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

255

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

444

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 990

Annual Return 2012

rr_AnnualReturn2012

12.04%

Annual Return 2013

rr_AnnualReturn2013

6.39%

Annual Return 2014

rr_AnnualReturn2014

2.41%

Annual Return 2015

rr_AnnualReturn2015

(1.14%)

Annual Return 2016

rr_AnnualReturn2016

11.51%

Annual Return 2017

rr_AnnualReturn2017

5.06%

Annual Return 2018

rr_AnnualReturn2018

0.39%

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Highest Quarterly Return: First Quarter 2012, 5.09%

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

5.09%

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Mar. 31, 2012

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Lowest Quarterly Return: Fourth Quarter 2018, -3.02%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(3.02%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Past 1 Year

rr_AverageAnnualReturnYear01

0.39%

Past 5 Years

rr_AverageAnnualReturnYear05

3.56%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

5.53%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(1.95%)

Past 5 Years

rr_AverageAnnualReturnYear05

0.97%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

2.93%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

0.26%

Past 5 Years

rr_AverageAnnualReturnYear05

1.54%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

3.13%

Inception Date

rr_AverageAnnualReturnInceptionDate

Sep. 30, 2011

(Vaughan Nelson Select Fund)

Prospectus:

rr_ProspectusTable

Objective [Heading]

rr_ObjectiveHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investment Goal </b></div>

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The Fund seeks long-term capital appreciation.

Expense [Heading]

rr_ExpenseHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Fund Fees & Expenses </b></div>

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 30 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Shareholder Fees</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(fees paid directly from your investment)</b></div>

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Annual Fund Operating Expenses</b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>(expenses that you pay each year as a percentage of the value of your investment)</b></div>

Fee Waiver or Reimbursement over Assets, Date of Termination

rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination

March 31, 2020

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Example </b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are redeemed:</b></div>

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>If shares are not redeemed:</b></div>

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Portfolio Turnover </b></div>

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 54% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

54.00%

Strategy [Heading]

rr_StrategyHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Investments, Risks and Performance </b></div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Strategies </b></div>

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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Principal Investment Risks </b></div>

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 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.

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. Potential future changes in government monetary policy may affect the level of interest rates, and the current historically low interest rate environment, combined with the Federal Reserve Board's conclusion of its quantitative easing program and recent increases in interest rates, increases the likelihood of interest rates rising in the future.

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 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 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

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> Risk/Return Bar Chart and Table </b></div>

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-class and life-of-fund 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 im.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.

Bar Chart [Heading]

rr_BarChartHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Total Returns for Class Y Shares</b></div>

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:
Fourth Quarter 2018, -15.44%

Performance Table Heading

rr_PerformanceTableHeading

<div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b>Average Annual Total Returns</b> </div> <div style="font-size:10pt;padding-top:5pt;padding-bottom:0;padding-left:0;"><b> (for the periods ended December 31, 2018)</b> </div>

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 Return After Taxes on Distributions and Sale of Fund Shares for the 1-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. 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 Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

The Return After Taxes on Distributions and Sale of Fund Shares for the 1-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-class and life-of-fund 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. After-tax returns for the other classes of the Fund will vary.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

im.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

(4.38%)

Past 5 Years

rr_AverageAnnualReturnYear05

8.49%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

12.16%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

(Vaughan Nelson Select Fund) | S&P 500® Index (3/31/17)

Prospectus:

rr_ProspectusTable

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

5.50%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

0.80%

^[7]

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

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.22%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.09%

^[8]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.36%

^[9],[10]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.07%

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

rr_NetExpensesOverAssets

1.29%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 699

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

974

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,271

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 2,110

Past 1 Year

rr_AverageAnnualReturnYear01

(10.25%)

Past 5 Years

rr_AverageAnnualReturnYear05

6.01%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

11.54%

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

0.80%

^[7]

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

rr_DistributionAndService12b1FeesOverAssets

1.00%

Other expenses

rr_OtherExpensesOverAssets

0.21%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.09%

^[8]

Total annual fund operating expenses

rr_ExpensesOverAssets

2.10%

^[9],[10]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.06%

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

rr_NetExpensesOverAssets

2.04%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 307

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

652

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

1,123

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,426

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

207

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

652

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

1,123

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,426

Past 1 Year

rr_AverageAnnualReturnYear01

(6.33%)

Past 5 Years

rr_AverageAnnualReturnYear05

6.48%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

11.73%

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

0.80%

^[7]

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

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

12.74%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.09%

^[8]

Total annual fund operating expenses

rr_ExpensesOverAssets

13.63%

^[9],[10]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

12.64%

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

2,694

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

4,862

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 8,842

Past 1 Year

rr_AverageAnnualReturnYear01

(4.62%)

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

5.85%

Inception Date

rr_AverageAnnualReturnInceptionDate

Mar. 31, 2017

(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

0.80%

^[7]

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

rr_DistributionAndService12b1FeesOverAssets

0.25%

Other expenses

rr_OtherExpensesOverAssets

0.22%

^[5]

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.09%

^[8]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.36%

^[9],[10]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.07%

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

rr_NetExpensesOverAssets

1.29%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 378

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

663

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

970

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,838

Past 1 Year

rr_AverageAnnualReturnYear01

(7.16%)

Past 5 Years

rr_AverageAnnualReturnYear05

6.74%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

12.11%

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

0.80%

^[7]

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

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses

rr_OtherExpensesOverAssets

0.21%

Acquired fund fees and expenses

rr_AcquiredFundFeesAndExpensesOverAssets

0.09%

^[8]

Total annual fund operating expenses

rr_ExpensesOverAssets

1.10%

^[9],[10]

Fee waiver and/or expense reimbursement

rr_FeeWaiverOrReimbursementOverAssets

0.06%

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

rr_NetExpensesOverAssets

1.04%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 106

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

344

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

600

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

$ 1,335

Annual Return 2013

rr_AnnualReturn2013

43.39%

Annual Return 2014

rr_AnnualReturn2014

10.76%

Annual Return 2015

rr_AnnualReturn2015

2.81%

Annual Return 2016

rr_AnnualReturn2016

6.94%

Annual Return 2017

rr_AnnualReturn2017

23.79%

Annual Return 2018

rr_AnnualReturn2018

(4.56%)

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: Fourth Quarter 2018, -15.44%

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(15.44%)

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2018

Past 1 Year

rr_AverageAnnualReturnYear01

(4.56%)

Past 5 Years

rr_AverageAnnualReturnYear05

7.55%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

12.84%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(6.80%)

Past 5 Years

rr_AverageAnnualReturnYear05

6.27%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

10.99%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

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

Prospectus:

rr_ProspectusTable

Past 1 Year

rr_AverageAnnualReturnYear01

(1.18%)

Past 5 Years

rr_AverageAnnualReturnYear05

5.87%

Life of Class N / Life of Fund

rr_AverageAnnualReturnSinceInception

9.93%

Inception Date

rr_AverageAnnualReturnInceptionDate

Jun. 29, 2012

[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] Other expenses have been restated to reflect current custodian fees for the Fund effective October 1, 2018.

[3] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 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, 2020 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.

[4] Natixis Advisors, L.P. ("Natixis Advisors") has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2020 and may be terminated before then only with the consent of the Fund's Board of Trustees.

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

[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 1.05%, 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, 2020 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.

[7] Management fees have been restated to reflect the current management fees for the Fund effective as of July 1, 2018.

[8] 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.

[9] Natixis Advisors has given a binding contractual undertaking to the Fund to reimburse any and all transfer agency expenses for Class N shares. This undertaking is in effect through March 31, 2020 and may be terminated before then only with the consent of the Fund's Board of Trustees.

[10] Natixis Advisors, L.P. ("Natixis Advisors") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.20%, 1.95%, 0.90%, 1.20% and 0.95% 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, 2020 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.