485BPOS

Registration Nos. 333-39133

811-06241

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. 65	x

and/or

REGISTRATION STATEMENT

UNDER

THE INVESTMENT COMPANY ACT OF 1940	¨
Amendment No. 68	x

(Check appropriate box or boxes.)

LOOMIS SAYLES FUNDS II

(Exact Name of Registrant as Specified in Charter)

399 Boylston Street

Boston, Massachusetts 02116

(Address of principal executive offices)    (Zip Code)

(617) 449-2810

(Registrant’s Telephone Number, including Area Code)

Copy to:

Coleen Downs Dinneen, Esq. Natixis Distribution, L.P. 399 Boylston Street Boston, Massachusetts 02116	John M. Loder, Esq. Ropes & Gray One International Place Boston, Massachusetts 02110
(Name and Address of Agent for Service)

Approximate Date of Public Offering

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

x 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.

LOOMIS SAYLES FUNDS 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 registration statement under Rule 485(b) under the Securities Act and has duly caused this Post-Effective Amendment No. 65 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 22^nd day of February, 2013.

LOOMIS SAYLES FUNDS II
By:	/S/    DAVID L. GIUNTA
	David L. Giunta President

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	President and Trustee	February 22, 2013
David L. Giunta
/S/    MICHAEL C. KARDOK	Treasurer	February 22, 2013
Michael C. Kardok
CHARLES D. BAKER*	Trustee	February 22, 2013
Charles D. Baker
ROBERT J. BLANDING*	Chief Executive Officer and Trustee	February 22, 2013
Robert J. Blanding
DANIEL M. CAIN*	Trustee	February 22, 2013
Daniel M. Cain
KENNETH A. DRUCKER*	Trustee	February 22, 2013
Kenneth A. Drucker
EDMOND J. ENGLISH*	Trustee	February 22, 2013
Edmond J. English
JOHN T. HAILER*	Trustee	February 22, 2013
John T. Hailer

WENDELL J. KNOX*
Wendell J. Knox	Trustee	February 22, 2013
MARTIN T. MEEHAN*
Martin T. Meehan	Trustee	February 22, 2013
SANDRA O. MOOSE*
Sandra O. Moose	Trustee, Chairperson of the Board	February 22, 2013
ERIK SIRRI*
Erik Sirri	Trustee	February 22, 2013
PETER SMAIL*
Peter Smail	Trustee	February 22, 2013
CYNTHIA L. WALKER*
Cynthia L. Walker	Trustee	February 22, 2013

*By:	/S/    COLEEN DOWNS DINEEN
	Coleen Downs Dinneen Attorney-In-Fact (a),(b),(c),(d),(e),(f),(g)(h)

February 22, 2013

^(a)  Powers of Attorney for Robert J. Blanding, Daniel M. Cain, John T. Hailer and Sandra O. Moose are incorporated by reference to exhibit (q) to PEA No. 37 to the Registration Statement filed on December 2, 2004.

^(b)  Power of Attorney for Cynthia L. Walker is incorporated by reference to exhibit (q)(2) to PEA No. 39 to the Registration Statement filed on December 2, 2005.

^(c) Power of Attorney for Kenneth A. Drucker is incorporated by reference to exhibit (q)(4) to PEA No. 50 to the Registration Statement filed on July 17, 2008.

^(d)  Power of Attorney for Wendell J. Knox is incorporated by reference to exhibit (q)(4) to PEA No. 55 to the Registration Statement filed on November 23, 2009.

^(e) Powers of Attorney for Erik Sirri and Peter Smail are incorporated by reference to exhibits (q)(5) and (q)(6) to PEA No. 56 to the Registration Statement filed on January 28, 2010.

^(f) Power of Attorney for Charles D. Baker is incorporated by reference to exhibit (q)(7) to PEA No. 57 to the Registration Statement filed on January 28, 2011.

^(g) Power of Attorney for Martin T. Meehan is incorporated by reference to exhibit (q)(9) to PEA No. 63 to the Registration Statement filed on November 29, 2012.

^(h) Power of Attorney for Edmond. J. English is incorporated by reference to exhibit (q)(10) to PEA No. 64 to the Registration Statement filed on January 28, 2013.

Loomis Sayles Funds 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
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Value Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Value Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment objective is long-term growth of capital and income.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 25% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	25.00%
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are estimated for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks, convertible securities and warrants. In deciding which securities to buy and sell, the Adviser generally looks for companies that it believes are undervalued by the market in relation to earnings, dividends, assets and/or growth prospects. The Fund’s investments may include companies that have suffered significant business problems but that the Adviser believes have favorable prospects for recovery. The Adviser seeks to identify companies that it believes are, among other things, attractively valued based on the Adviser’s estimate of intrinsic value. The Adviser generally seeks to find value by selecting individual stocks that it believes are attractive, rather than by attempting to achieve investment growth by rotating the Fund’s holdings among various sectors of the economy. The Fund may also invest up to 20% of its assets in securities of foreign issuers including emerging market securities, invest in options for hedging and investment purposes, real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as options transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund. Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2003, 18.11% Lowest Quarterly Return: Fourth Quarter 2008, -19.58% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the table for Class A shares prior to June 1, 2007 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Retail Class shares (June 30, 2006), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class A shares. Prior to the inception of Class B and Class C shares (June 1, 2007), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B and Class C shares, respectively. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. 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-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Value Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.98%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.98%
1 year	rr_ExpenseExampleYear01	669
3 years	rr_ExpenseExampleYear03	869
5 years	rr_ExpenseExampleYear05	1,086
10 years	rr_ExpenseExampleYear10	1,707
Past 1 Year	rr_AverageAnnualReturnYear01	12.52%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.62%)
Past 10 Years	rr_AverageAnnualReturnYear10	7.57%
Loomis Sayles Value Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.73%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.73%
1 year	rr_ExpenseExampleYear01	676
3 years	rr_ExpenseExampleYear03	845
5 years	rr_ExpenseExampleYear05	1,139
10 years	rr_ExpenseExampleYear10	1,842
1 year	rr_ExpenseExampleNoRedemptionYear01	176
3 years	rr_ExpenseExampleNoRedemptionYear03	545
5 years	rr_ExpenseExampleNoRedemptionYear05	939
10 years	rr_ExpenseExampleNoRedemptionYear10	1,842
Past 1 Year	rr_AverageAnnualReturnYear01	13.59%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.58%)
Past 10 Years	rr_AverageAnnualReturnYear10	7.33%
Loomis Sayles Value Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.73%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.73%
1 year	rr_ExpenseExampleYear01	276
3 years	rr_ExpenseExampleYear03	545
5 years	rr_ExpenseExampleYear05	939
10 years	rr_ExpenseExampleYear10	2,041
1 year	rr_ExpenseExampleNoRedemptionYear01	176
3 years	rr_ExpenseExampleNoRedemptionYear03	545
5 years	rr_ExpenseExampleNoRedemptionYear05	939
10 years	rr_ExpenseExampleNoRedemptionYear10	2,041
Past 1 Year	rr_AverageAnnualReturnYear01	17.49%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.18%)
Past 10 Years	rr_AverageAnnualReturnYear10	7.33%
Loomis Sayles Value Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.08%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.58%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.58%
1 year	rr_ExpenseExampleYear01	59
3 years	rr_ExpenseExampleYear03	186
5 years	rr_ExpenseExampleYear05	324
10 years	rr_ExpenseExampleYear10	726
Past 1 Year	rr_AverageAnnualReturnYear01	19.70%
Past 5 Years	rr_AverageAnnualReturnYear05	0.85%
Past 10 Years	rr_AverageAnnualReturnYear10	8.52%
Loomis Sayles Value Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.23%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.73%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.73%
1 year	rr_ExpenseExampleYear01	75
3 years	rr_ExpenseExampleYear03	233
5 years	rr_ExpenseExampleYear05	406
10 years	rr_ExpenseExampleYear10	906
2003	rr_AnnualReturn2003	26.24%
2004	rr_AnnualReturn2004	15.12%
2005	rr_AnnualReturn2005	12.80%
2006	rr_AnnualReturn2006	24.75%
2007	rr_AnnualReturn2007	6.17%
2008	rr_AnnualReturn2008	(33.32%)
2009	rr_AnnualReturn2009	20.16%
2010	rr_AnnualReturn2010	11.94%
2011	rr_AnnualReturn2011	(2.81%)
2012	rr_AnnualReturn2012	19.70%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.11%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.58%)
Past 1 Year	rr_AverageAnnualReturnYear01	19.70%
Past 5 Years	rr_AverageAnnualReturnYear05	0.85%
Past 10 Years	rr_AverageAnnualReturnYear10	8.52%
Loomis Sayles Value Fund | Admin Class
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.49%	[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.24%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.24%
1 year	rr_ExpenseExampleYear01	126
3 years	rr_ExpenseExampleYear03	393
5 years	rr_ExpenseExampleYear05	681
10 years	rr_ExpenseExampleYear10	1,500
Past 1 Year	rr_AverageAnnualReturnYear01	19.04%
Past 5 Years	rr_AverageAnnualReturnYear05	0.30%
Past 10 Years	rr_AverageAnnualReturnYear10	7.92%
Loomis Sayles Value Fund | Return After Taxes on Distributions | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	19.42%
Past 5 Years	rr_AverageAnnualReturnYear05	0.62%
Past 10 Years	rr_AverageAnnualReturnYear10	8.02%
Loomis Sayles Value Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	13.18%
Past 5 Years	rr_AverageAnnualReturnYear05	0.69%
Past 10 Years	rr_AverageAnnualReturnYear10	7.43%
Loomis Sayles Value Fund | Russell 1000 Value Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	17.51%
Past 5 Years	rr_AverageAnnualReturnYear05	0.59%
Past 10 Years	rr_AverageAnnualReturnYear10	7.38%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.10%, 1.85%, 1.85%, 0.80%, 0.85% and 1.35% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.10%, 1.85%, 1.85%, 0.80%, 0.85% and 1.35% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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

[3] Other expenses include an administrative services fee of 0.25% for Admin Class shares.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Small Cap Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	loomis sayles small cap growth fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment objective is long-term capital growth from investments in common stocks or other equity securities.
Expense [Heading]	rr_ExpenseHeading	FUND FEES & EXPENSES
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. The Fund does not impose a sales charge, a redemption fee or an exchange fee.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	ANNUAL FUND OPERATING EXPENSES (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 77% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	77.00%
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are based on estimated amounts for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The 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. The example also assumes that your investment has a 5% return each year and the Fund’s operating expenses remain the same. The example for the Institutional Class shares and the Class N shares is based on Total Annual Fund Operating Expenses for all periods. The example for Retail Class shares is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	INVESTMENTS, RISKS AND PERFORMANCE Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in the equity securities of “small-cap companies,” including preferred stocks, warrants, securities convertible into common or preferred stocks and other equity-like interests in an entity. Currently, the Fund defines a small-cap company to be one whose market capitalization either falls within the capitalization range of the Russell 2000 Index, an index that tracks stocks of 2,000 of the smallest U.S. companies, or is $3 billion or less at the time of investment. The Fund may invest the rest of its assets in companies of any size, including large-capitalization companies. In deciding which securities to buy and sell, Loomis Sayles typically seeks to identify companies that it believes have distinctive products, technologies, or services; dynamic earnings growth; prospects for high levels of profitability; and solid management. Loomis Sayles typically does not consider current income when making buy/sell decisions. The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in other foreign securities, including emerging markets securities. The Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”). The Fund may engage, for hedging and investment purposes, in foreign currency transactions, options and futures transactions.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Credit Risk is the risk that the issuer or guarantor of a fixed-income security in which the Fund invests, or the counterparty to a derivatives or other transaction will fail financially or otherwise be unwilling or unable to meet their obligations to the Fund. Currency Risk is the risk that the value of the Fund’s investments will fall as a result of changes in exchange rates. Loomis Sayles may elect not to hedge currency risk or may hedge imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk is the risk that the value of the Fund’s derivative investments such as forward currency contracts, options and futures transactions will fall, for example, because of changes in the value of the underlying reference instruments, pricing difficulties or lack of correlation with the underlying investments. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. There is also the risk that the Fund may be unable to terminate or sell a derivatives position at an advantageous time or price. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. This risk is greater for forward currency contracts and other over-the-counter traded derivatives. Investing in derivatives gives rise to other risks, such as leverage risk, liquidity risk, credit risk, counterparty risk, interest rate risk and market risk. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. Emerging Markets Risk is the risk that the Fund’s investments may face greater foreign securities risk. Investing in companies traded in emerging securities markets, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Equity Securities Risk is the risk that the value of a stock may decline for a number of reasons that relate directly to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services, or the equity markets generally. 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 Loomis Sayles’ assessment of the prospects for a company’s growth is wrong, or if Loomis Sayles’ 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 Loomis Sayles has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Foreign Securities Risk is the risk that the value of the Fund’s foreign investments will fall as a result of foreign political, social, economic, environmental, credit, informational or currency changes or other issues relating to foreign investing generally. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. The Fund’s investments in foreign securities may be subject to foreign withholding taxes, which would decrease the yield on those securities. Issuer Risk is the risk that the value of securities may decline due to a number of reasons relating to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. Leverage Risk is the risk associated with securities or practices (e.g., borrowing and the use of certain derivatives) and investment in certain types of derivatives that multiply small index, market or asset price movements into larger changes in value. Use of derivative instruments may involve leverage. When a derivative is used as a hedge against an offsetting position that the Fund also holds, any loss generated by the derivative should be substantially offset by gains on the hedged instrument, and vice versa. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. Futures and forward currency contracts are derivatives and may be subject to this type of risk. Liquidity Risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Liquidity issues may also make it difficult to value the Fund’s investments. Management Risk is the risk that Loomis Sayles’ investment techniques will be unsuccessful and cause the Fund to incur losses. Market Risk is the risk that the market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. Small-Capitalization Companies Risk is the risk that the Fund’s investments may be subject to more abrupt price movements, limited markets, increased volatility and less liquidity than investments in larger, more established companies, which could adversely affect the value of the portfolio.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year, ten-year and life-of-fund periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at www.loomissayles.com and/or by calling the Fund toll-free at 800-633-3330.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year, ten-year and life-of-fund periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-633-3330
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.loomissayles.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Institutional Class Shares
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	The Fund’s best quarter was 25.29%, (second quarter of 2003), and the Fund’s worst quarter was -26.86%, (fourth quarter of 2008).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns for the periods ended December 31, 2012
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-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for the Institutional Class of the Fund. After-tax returns for other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of the Institutional Class shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Institutional Class shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Institutional Class shares because Institutional Class shares are subject to higher expenses. 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-deferred 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 the Institutional Class of the Fund. After-tax returns for other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.
Loomis Sayles Small Cap Growth Fund | Institutional Class
Risk/Return:	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.20%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.95%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.95%
1 year	rr_ExpenseExampleYear01	97
3 years	rr_ExpenseExampleYear03	303
5 years	rr_ExpenseExampleYear05	525
10 years	rr_ExpenseExampleYear10	1,166
2003	rr_AnnualReturn2003	43.32%
2004	rr_AnnualReturn2004	9.43%
2005	rr_AnnualReturn2005	10.69%
2006	rr_AnnualReturn2006	14.31%
2007	rr_AnnualReturn2007	24.26%
2008	rr_AnnualReturn2008	(39.80%)
2009	rr_AnnualReturn2009	31.90%
2010	rr_AnnualReturn2010	31.40%
2011	rr_AnnualReturn2011	3.20%
2012	rr_AnnualReturn2012	10.29%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	best quarter
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	25.29%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	worst quarter
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(26.86%)
One Year	rr_AverageAnnualReturnYear01	10.29%
Five Years	rr_AverageAnnualReturnYear05	3.50%
Ten Years	rr_AverageAnnualReturnYear10	11.34%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Loomis Sayles Small Cap Growth Fund | Retail Class
Risk/Return:	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.28%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.28%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.03%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.25%
1 year	rr_ExpenseExampleYear01	127
3 years	rr_ExpenseExampleYear03	403
5 years	rr_ExpenseExampleYear05	699
10 years	rr_ExpenseExampleYear10	1,543
One Year	rr_AverageAnnualReturnYear01	9.96%
Five Years	rr_AverageAnnualReturnYear05	3.22%
Ten Years	rr_AverageAnnualReturnYear10	11.04%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.53%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Loomis Sayles Small Cap Growth Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.10%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.85%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.85%
1 year	rr_ExpenseExampleYear01	87
3 years	rr_ExpenseExampleYear03	271
5 years	rr_ExpenseExampleYear05	471
10 years	rr_ExpenseExampleYear10	1,049
One Year	rr_AverageAnnualReturnYear01	10.29%
Five Years	rr_AverageAnnualReturnYear05	3.50%
Ten Years	rr_AverageAnnualReturnYear10	11.34%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.80%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Loomis Sayles Small Cap Growth Fund | Return After Taxes on Distributions | Institutional Class
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	10.29%
Five Years	rr_AverageAnnualReturnYear05	3.50%
Ten Years	rr_AverageAnnualReturnYear10	11.34%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Loomis Sayles Small Cap Growth Fund | Return After Taxes on Distributions and Sale of Fund Shares | Institutional Class
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	6.69%
Five Years	rr_AverageAnnualReturnYear05	3.00%
Ten Years	rr_AverageAnnualReturnYear10	10.19%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.12%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996
Loomis Sayles Small Cap Growth Fund | Russell 2000 Growth Index
Risk/Return:	rr_RiskReturnAbstract
One Year	rr_AverageAnnualReturnYear01	14.59%
Five Years	rr_AverageAnnualReturnYear05	3.49%
Ten Years	rr_AverageAnnualReturnYear10	9.80%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.58%
Inception Date	rr_AverageAnnualReturnInceptionDate	Dec. 31, 1996

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.00%, 1.25% and 0.95% of the Fund's average daily net assets for Institutional Class shares, Retail Class shares and Class N 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.00%, 1.25% and 0.95% of the Fund's average daily net assets for Institutional Class shares, Retail Class shares and Class N shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

[2] Other expenses for Class N shares are based on estimated amounts for the current fiscal year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Strategic Income Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Strategic Income Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high current income
Objective, Secondary [Text Block]	rr_ObjectiveSecondaryTextBlock	with a secondary objective of capital growth.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy 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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 30% the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	30.00%
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are estimated for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest substantially all of its assets in income producing securities (including below investment-grade securities, or “junk bonds”) with a focus on U.S. corporate bonds, convertible securities, foreign debt instruments, including those in emerging markets and related foreign currency transactions, and U.S. government securities. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. The Fund may invest up to 35% of its assets in preferred stocks and dividend-paying common stocks. The portfolio managers may shift the Fund’s assets among various types of income-producing securities based upon changing market conditions. The Adviser performs its own extensive credit analyses to determine the creditworthiness and potential for capital appreciation of a security. The Fund’s portfolio managers use a flexible approach to identify securities in the global marketplace with characteristics including discounted price compared to economic value, undervalued credit ratings with strong or improving credit profiles and yield premium relative to its benchmark (although not all of the securities selected will have these attributes). In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments. In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser seeks to buy bonds that offer a positive yield advantage over the market and, in its view, have room to increase in price. It may also invest to take advantage of what the portfolio managers believe are temporary disparities in the yield of different segments of the market for U.S. government securities. The Adviser provides the portfolio managers with maximum flexibility to find investment opportunities in a wide range of markets, both domestic and foreign. This flexible approach provides the Fund with access to a wide array of investment opportunities. The three key sectors that the portfolio managers focus upon are U.S. corporate issues (including convertible securities), foreign debt securities and U.S. government securities. The Fund’s portfolio managers maintain a core of the Fund’s investments in corporate bond issues and shift its assets among other income-producing securities as opportunities develop. The Fund generally seeks to maintain a high level of diversification as a form of risk management. In connection with its principal investment strategies, the Fund may also invest in securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), structured notes, zero-coupon bonds, pay-in-kind bonds, mortgage-related securities, stripped securities and futures, swaps (including credit default swaps) and foreign currency transactions for hedging and investment purposes. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Equity Securities Risk: The value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. 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 an unexpected 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. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2009, 18.02% Lowest Quarterly Return: Third Quarter 2008, -13.38% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the bar chart and table for the periods prior to September 15, 2003 reflect the results of the CDC Nvest Strategic Income Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Strategic Income Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.15%	[1],[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.96%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.96%
1 year	rr_ExpenseExampleYear01	544
3 years	rr_ExpenseExampleYear03	742
5 years	rr_ExpenseExampleYear05	957
10 years	rr_ExpenseExampleYear10	1,575
2003	rr_AnnualReturn2003	34.84%
2004	rr_AnnualReturn2004	12.93%
2005	rr_AnnualReturn2005	3.74%
2006	rr_AnnualReturn2006	11.86%
2007	rr_AnnualReturn2007	7.26%
2008	rr_AnnualReturn2008	(23.15%)
2009	rr_AnnualReturn2009	39.30%
2010	rr_AnnualReturn2010	13.53%
2011	rr_AnnualReturn2011	3.35%
2012	rr_AnnualReturn2012	13.56%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	18.02%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(13.38%)
Past 1 Year	rr_AverageAnnualReturnYear01	9.59%
Past 5 Years	rr_AverageAnnualReturnYear05	6.60%
Past 10 Years	rr_AverageAnnualReturnYear10	10.06%
Loomis Sayles Strategic Income Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.15%	[1],[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.71%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.71%
1 year	rr_ExpenseExampleYear01	674
3 years	rr_ExpenseExampleYear03	839
5 years	rr_ExpenseExampleYear05	1,128
10 years	rr_ExpenseExampleYear10	1,821
1 year	rr_ExpenseExampleNoRedemptionYear01	174
3 years	rr_ExpenseExampleNoRedemptionYear03	539
5 years	rr_ExpenseExampleNoRedemptionYear05	928
10 years	rr_ExpenseExampleNoRedemptionYear10	1,821
Past 1 Year	rr_AverageAnnualReturnYear01	7.75%
Past 5 Years	rr_AverageAnnualReturnYear05	6.23%
Past 10 Years	rr_AverageAnnualReturnYear10	9.62%
Loomis Sayles Strategic Income Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.15%	[1],[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.71%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.71%
1 year	rr_ExpenseExampleYear01	274
3 years	rr_ExpenseExampleYear03	539
5 years	rr_ExpenseExampleYear05	928
10 years	rr_ExpenseExampleYear10	2,019
1 year	rr_ExpenseExampleNoRedemptionYear01	174
3 years	rr_ExpenseExampleNoRedemptionYear03	539
5 years	rr_ExpenseExampleNoRedemptionYear05	928
10 years	rr_ExpenseExampleNoRedemptionYear10	2,019
Past 1 Year	rr_AverageAnnualReturnYear01	11.70%
Past 5 Years	rr_AverageAnnualReturnYear05	6.55%
Past 10 Years	rr_AverageAnnualReturnYear10	9.63%
Loomis Sayles Strategic Income Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.06%	[1],[2],[4]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.62%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.62%
1 year	rr_ExpenseExampleYear01	63
3 years	rr_ExpenseExampleYear03	199
5 years	rr_ExpenseExampleYear05	346
10 years	rr_ExpenseExampleYear10	774
Past 1 Year	rr_AverageAnnualReturnYear01	13.93%
Past 5 Years	rr_AverageAnnualReturnYear05	7.63%
Past 10 Years	rr_AverageAnnualReturnYear10	10.74%
Loomis Sayles Strategic Income Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.15%	[1],[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.71%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.71%
1 year	rr_ExpenseExampleYear01	73
3 years	rr_ExpenseExampleYear03	227
5 years	rr_ExpenseExampleYear05	395
10 years	rr_ExpenseExampleYear10	883
Past 1 Year	rr_AverageAnnualReturnYear01	13.93%
Past 5 Years	rr_AverageAnnualReturnYear05	7.63%
Past 10 Years	rr_AverageAnnualReturnYear10	10.74%
Loomis Sayles Strategic Income Fund | Admin Class
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.56%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.40%	[1],[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.21%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[3]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.21%
1 year	rr_ExpenseExampleYear01	123
3 years	rr_ExpenseExampleYear03	384
5 years	rr_ExpenseExampleYear05	665
10 years	rr_ExpenseExampleYear10	1,466
Past 1 Year	rr_AverageAnnualReturnYear01	13.33%
Past 5 Years	rr_AverageAnnualReturnYear05	7.06%
Past 10 Years	rr_AverageAnnualReturnYear10	10.13%
Loomis Sayles Strategic Income Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	7.73%
Past 5 Years	rr_AverageAnnualReturnYear05	4.31%
Past 10 Years	rr_AverageAnnualReturnYear10	7.75%
Loomis Sayles Strategic Income Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	6.33%
Past 5 Years	rr_AverageAnnualReturnYear05	4.25%
Past 10 Years	rr_AverageAnnualReturnYear10	7.38%
Loomis Sayles Strategic Income Fund | Barclays U.S. Aggregate Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	4.21%
Past 5 Years	rr_AverageAnnualReturnYear05	5.95%
Past 10 Years	rr_AverageAnnualReturnYear10	5.18%
Loomis Sayles Strategic Income Fund | Barclays U.S. Universal Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	5.53%
Past 5 Years	rr_AverageAnnualReturnYear05	6.19%
Past 10 Years	rr_AverageAnnualReturnYear10	5.59%

[1] Other expenses include an administrative service fee of 0.25% for Admin Class shares.

[2] The expense information shown in the table above may differ from the expense information disclosed in the Fund's financial highlights table because the financial highlights table reflects the operating expenses of the Fund and does not include acquired fund fees and expenses (expenses indirectly borne by the Fund through investments in certain pooled investment vehicles).

[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 1.25%, 2.00%, 2.00%, 0.95%, 1.00% and 1.50 % of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 2.00%, 0.95%, 1.00% and 1.50 % of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Investment Grade Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Investment Grade Bond Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high total investment return through a combination of current income and capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy 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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 19% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	19.00%
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are estimated for the current fiscal year.
Expense Example by Year [Heading]	rr_ExpenseExampleByYearHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investment-grade fixed-income securities (for example, bonds and other investments that Loomis Sayles believes have similar economic characteristics, such as notes, debentures and loans). “Investment-grade” securities are those securities that are rated as such at the time of purchase by at least one of the three major rating agencies —  Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investor Services, Inc. (“Fitch”) or Standard & Poor’s Ratings Group (“S&P”) or, if unrated, are determined by the Adviser to be of comparable quality. Although the Fund invests primarily in investment-grade fixed-income securities, it may invest up to 10% of its assets in below investment-grade fixed-income securities (also known as “junk bonds”). The Fund has the flexibility to invest up to 10% of its assets in equity securities (such as common stocks, preferred stocks and investment companies), but will limit its investments in common stocks to 5% of its assets. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major rating agencies (Moody’s, Fitch or S&P) have rated the securities in one of their top four ratings categories) or, if unrated, are determined by the Adviser to be of comparable quality. There is no minimum rating for the securities in which the Fund may invest. The Fund may invest in fixed income-securities of any maturity. In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments. Three themes typically drive the Fund’s investment approach. First, the Adviser generally seeks fixed-income securities of issuers whose credit profiles it believes are improving. Second, the Fund may invest significantly in securities the prices of which the Adviser believes are more sensitive to events related to the underlying issuer than to changes in general interest rates or overall market default rates. The Adviser believes that the Fund may generate positive returns by having a portion of the Fund’s assets invested in non-market-related securities, rather than by relying primarily on changes in interest rates to produce returns for the Fund. Third, the Adviser analyzes different sectors of the economy and differences in the yields (“spreads”) of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk. The Adviser generally prefers securities that are protected against calls (early redemption by the issuer). In connection with its principal investment strategies, the Fund may also invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in securities of other foreign issuers, including emerging markets securities. The Fund may also invest in obligations of supranational entities without limit ( e.g. , the World Bank), corporate securities, U.S. government securities, commercial paper, zero-coupon securities, mortgage-backed securities, including mortgage dollar rolls, stripped mortgage-backed securities and collateralized mortgage obligations and other asset-backed securities, when-issued securities, convertible securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”) and structured notes. The Fund may also engage in foreign currency hedging transactions and swap transactions (including credit default swaps) for hedging or investment purposes. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, and swap transactions 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 traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Equity Securities Risk: The value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. 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 an unexpected 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. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2009, 12.65% Lowest Quarterly Return: Third Quarter 2008, -7.19% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the table for Class A shares prior to September 15, 2003 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class B and Class C shares (September 12, 2003), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B and Class C shares, respectively. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Investment Grade Bond Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.19%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.84%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.84%
1 year	rr_ExpenseExampleYear01	532
3 years	rr_ExpenseExampleYear03	706
5 years	rr_ExpenseExampleYear05	895
10 years	rr_ExpenseExampleYear10	1,440
Past 1 Year	rr_AverageAnnualReturnYear01	6.96%
Past 5 Years	rr_AverageAnnualReturnYear05	6.95%
Past 10 Years	rr_AverageAnnualReturnYear10	8.21%
Loomis Sayles Investment Grade Bond Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.19%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.59%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.59%
1 year	rr_ExpenseExampleYear01	662
3 years	rr_ExpenseExampleYear03	802
5 years	rr_ExpenseExampleYear05	1,066
10 years	rr_ExpenseExampleYear10	1,688
1 year	rr_ExpenseExampleNoRedemptionYear01	162
3 years	rr_ExpenseExampleNoRedemptionYear03	502
5 years	rr_ExpenseExampleNoRedemptionYear05	866
10 years	rr_ExpenseExampleNoRedemptionYear10	1,688
Past 1 Year	rr_AverageAnnualReturnYear01	6.10%
Past 5 Years	rr_AverageAnnualReturnYear05	6.77%
Past 10 Years	rr_AverageAnnualReturnYear10	7.82%
Loomis Sayles Investment Grade Bond Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.19%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.59%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.59%
1 year	rr_ExpenseExampleYear01	262
3 years	rr_ExpenseExampleYear03	502
5 years	rr_ExpenseExampleYear05	866
10 years	rr_ExpenseExampleYear10	1,889
1 year	rr_ExpenseExampleNoRedemptionYear01	162
3 years	rr_ExpenseExampleNoRedemptionYear03	502
5 years	rr_ExpenseExampleNoRedemptionYear05	866
10 years	rr_ExpenseExampleNoRedemptionYear10	1,889
Past 1 Year	rr_AverageAnnualReturnYear01	10.15%
Past 5 Years	rr_AverageAnnualReturnYear05	7.13%
Past 10 Years	rr_AverageAnnualReturnYear10	7.87%
Loomis Sayles Investment Grade Bond Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.07%	[1],[3]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.47%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.47%
1 year	rr_ExpenseExampleYear01	48
3 years	rr_ExpenseExampleYear03	151
5 years	rr_ExpenseExampleYear05	263
10 years	rr_ExpenseExampleYear10	591
Past 1 Year	rr_AverageAnnualReturnYear01	12.25%
Past 5 Years	rr_AverageAnnualReturnYear05	8.20%
Past 10 Years	rr_AverageAnnualReturnYear10	9.01%
Loomis Sayles Investment Grade Bond Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.19%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.59%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.59%
1 year	rr_ExpenseExampleYear01	60
3 years	rr_ExpenseExampleYear03	189
5 years	rr_ExpenseExampleYear05	329
10 years	rr_ExpenseExampleYear10	738
2003	rr_AnnualReturn2003	19.61%
2004	rr_AnnualReturn2004	9.91%
2005	rr_AnnualReturn2005	2.34%
2006	rr_AnnualReturn2006	8.07%
2007	rr_AnnualReturn2007	9.93%
2008	rr_AnnualReturn2008	(11.42%)
2009	rr_AnnualReturn2009	27.27%
2010	rr_AnnualReturn2010	11.52%
2011	rr_AnnualReturn2011	5.08%
2012	rr_AnnualReturn2012	12.25%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	12.65%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(7.19%)
Past 1 Year	rr_AverageAnnualReturnYear01	12.25%
Past 5 Years	rr_AverageAnnualReturnYear05	8.20%
Past 10 Years	rr_AverageAnnualReturnYear10	9.01%
Loomis Sayles Investment Grade Bond Fund | Admin Class
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.40%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.44%	[1]
Total annual fund operating expenses	rr_ExpensesOverAssets	1.09%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[2]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.09%
1 year	rr_ExpenseExampleYear01	111
3 years	rr_ExpenseExampleYear03	347
5 years	rr_ExpenseExampleYear05	601
10 years	rr_ExpenseExampleYear10	1,329
Past 1 Year	rr_AverageAnnualReturnYear01	14.90%
Past 5 Years	rr_AverageAnnualReturnYear05	8.19%
Past 10 Years	rr_AverageAnnualReturnYear10	8.53%
Loomis Sayles Investment Grade Bond Fund | Return After Taxes on Distributions | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	10.11%
Past 5 Years	rr_AverageAnnualReturnYear05	5.89%
Past 10 Years	rr_AverageAnnualReturnYear10	6.61%
Loomis Sayles Investment Grade Bond Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	8.11%
Past 5 Years	rr_AverageAnnualReturnYear05	5.67%
Past 10 Years	rr_AverageAnnualReturnYear10	6.39%
Loomis Sayles Investment Grade Bond Fund | Barclays U.S. Government/Credit Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	4.82%
Past 5 Years	rr_AverageAnnualReturnYear05	6.06%
Past 10 Years	rr_AverageAnnualReturnYear10	5.25%

[1] Other expenses include an administrative services fee of 0.25% for Admin Class shares.

[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 0.95%, 1.70%, 1.70%, 0.65%, 0.70% and 1.20% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 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 0.95%, 1.70%, 1.70%, 0.65%, 0.70% and 1.20% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

[3] Other expenses for Class N shares are estimated for the current fiscal year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Mid Cap Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Mid Cap Growth Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment objective is long-term capital growth from investments in common stocks or similar securities.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 191% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	191.00%
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are estimated for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in common stocks or other equity securities, including preferred stocks, warrants, securities convertible into common or preferred stocks and other equity-like interests in companies whose market capitalization falls within the Russell Midcap Growth Index. While the market capitalization range for this index fluctuates, at December 31, 2012, it was $337 million to $21 billion. The Fund may invest the rest of its assets in companies of any size. In deciding which securities to buy and sell, the Adviser seeks to identify companies that it believes have distinctive products, technologies or services, dynamic earnings growth, prospects for high levels of profitability and/or solid management. The Adviser typically does not consider current income when making buy/sell decisions. The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in other foreign securities, including emerging markets securities. The Fund may engage in foreign currency transactions, options for hedging and investment purposes and futures transactions, and may also engage in securities lending. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. The Fund also may invest in securities offered in the secondary markets or in initial public offerings, real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”). The Fund may engage in active and frequent trading of securities. Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts and options and futures transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Equity Securities Risk: The value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio manager may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund. Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2003, 19.49% Lowest Quarterly Return: Third Quarter 2008, -26.07%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	The Return After Taxes on Distributions & Sale of Fund Shares for the 5-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 Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the chart and table for Class A shares prior to February 1, 2009 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class C shares (February 2, 2009), performance is that of Retail Class shares, which were redesignated as Class A shares, restated to reflect the higher net expenses and sales loads of Class C shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. The Fund (formerly, Loomis Sayles Aggressive Growth Fund) changed its name and revised its investment strategies on February 1, 2007. The Fund’s performance may have been different had the current investment strategies been in place for all of the periods shown. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-deferred 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. The Return After Taxes on Distributions & Sale of Fund Shares for the 5-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. Index performance reflects no deduction for fees, expenses or taxes.
Loomis Sayles Mid Cap Growth Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.38%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.38%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.13%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.25%
1 year	rr_ExpenseExampleYear01	695
3 years	rr_ExpenseExampleYear03	975
5 years	rr_ExpenseExampleYear05	1,275
10 years	rr_ExpenseExampleYear10	2,127
2003	rr_AnnualReturn2003	39.71%
2004	rr_AnnualReturn2004	18.97%
2005	rr_AnnualReturn2005	15.16%
2006	rr_AnnualReturn2006	6.68%
2007	rr_AnnualReturn2007	39.39%
2008	rr_AnnualReturn2008	(45.66%)
2009	rr_AnnualReturn2009	26.44%
2010	rr_AnnualReturn2010	34.54%
2011	rr_AnnualReturn2011	(7.33%)
2012	rr_AnnualReturn2012	12.60%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2003
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.49%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(26.07%)
Past 1 Year	rr_AverageAnnualReturnYear01	6.14%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.89%)
Past 10 Years	rr_AverageAnnualReturnYear10	9.98%
Loomis Sayles Mid Cap Growth Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.38%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.13%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.13%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	2.00%
1 year	rr_ExpenseExampleYear01	303
3 years	rr_ExpenseExampleYear03	654
5 years	rr_ExpenseExampleYear05	1,132
10 years	rr_ExpenseExampleYear10	2,452
1 year	rr_ExpenseExampleNoRedemptionYear01	203
3 years	rr_ExpenseExampleNoRedemptionYear03	654
5 years	rr_ExpenseExampleNoRedemptionYear05	1,132
10 years	rr_ExpenseExampleNoRedemptionYear10	2,452
Past 1 Year	rr_AverageAnnualReturnYear01	10.77%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.46%)
Past 10 Years	rr_AverageAnnualReturnYear10	9.77%
Loomis Sayles Mid Cap Growth Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.22%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.97%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.02%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.95%
1 year	rr_ExpenseExampleYear01	97
3 years	rr_ExpenseExampleYear03	307
5 years	rr_ExpenseExampleYear05	534
10 years	rr_ExpenseExampleYear10	1,188
Past 1 Year	rr_AverageAnnualReturnYear01	12.93%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.46%)
Past 10 Years	rr_AverageAnnualReturnYear10	10.92%
Loomis Sayles Mid Cap Growth Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.38%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.13%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.13%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.00%
1 year	rr_ExpenseExampleYear01	102
3 years	rr_ExpenseExampleYear03	346
5 years	rr_ExpenseExampleYear05	610
10 years	rr_ExpenseExampleYear10	1,363
Past 1 Year	rr_AverageAnnualReturnYear01	12.93%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.46%)
Past 10 Years	rr_AverageAnnualReturnYear10	10.92%
Loomis Sayles Mid Cap Growth Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	6.14%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.89%)
Past 10 Years	rr_AverageAnnualReturnYear10	9.95%
Loomis Sayles Mid Cap Growth Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	3.99%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.59%)
Past 10 Years	rr_AverageAnnualReturnYear10	8.90%
Loomis Sayles Mid Cap Growth Fund | Russell Midcap Growth Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	15.81%
Past 5 Years	rr_AverageAnnualReturnYear05	3.23%
Past 10 Years	rr_AverageAnnualReturnYear10	10.32%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.25%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, C, N and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, C, N and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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

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Loomis Sayles Investment Grade Bond Fund

Loomis Sayles Investment Grade Bond Fund

Investment Goal

The Fund seeks high total investment return through a combination of current income and capital appreciation.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Investment Grade Bond Fund	Class A	Class B	Class C	Class N	Class Y	Admin Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%	none	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none	none	none
Redemption fees	none	none	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Investment Grade Bond Fund		Class A	Class B	Class C	Class N		Class Y	Admin Class
Management fees		0.40%	0.40%	0.40%	0.40%		0.40%	0.40%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none		none	0.25%
Other expenses	[1]	0.19%	0.19%	0.19%	0.07%	[2]	0.19%	0.44%
Total annual fund operating expenses		0.84%	1.59%	1.59%	0.47%		0.59%	1.09%
Fee waiver and/or expense reimbursement	[3]	none	none	none	none		none	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.84%	1.59%	1.59%	0.47%		0.59%	1.09%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If shares are redeemed:

Expense Example Loomis Sayles Investment Grade Bond Fund (USD $)	1 year	3 years	5 years	10 years
Class A	532	706	895	1,440
Class B	662	802	1,066	1,688
Class C	262	502	866	1,889
Class N	48	151	263	591
Class Y	60	189	329	738
Admin Class	111	347	601	1,329

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles Investment Grade Bond Fund (USD $)	1 year	3 years	5 years	10 years
Class B	162	502	866	1,688
Class C	162	502	866	1,889

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 19% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investment-grade fixed-income securities (for example, bonds and other investments that Loomis Sayles believes have similar economic characteristics, such as notes, debentures and loans). “Investment-grade” securities are those securities that are rated as such at the time of purchase by at least one of the three major rating agencies —  Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investor Services, Inc. (“Fitch”) or Standard & Poor’s Ratings Group (“S&P”) or, if unrated, are determined by the Adviser to be of comparable quality. Although the Fund invests primarily in investment-grade fixed-income securities, it may invest up to 10% of its assets in below investment-grade fixed-income securities (also known as “junk bonds”). The Fund has the flexibility to invest up to 10% of its assets in equity securities (such as common stocks, preferred stocks and investment companies), but will limit its investments in common stocks to 5% of its assets. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major rating agencies (Moody’s, Fitch or S&P) have rated the securities in one of their top four ratings categories) or, if unrated, are determined by the Adviser to be of comparable quality. There is no minimum rating for the securities in which the Fund may invest. The Fund may invest in fixed income-securities of any maturity.

In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.

Three themes typically drive the Fund’s investment approach. First, the Adviser generally seeks fixed-income securities of issuers whose credit profiles it believes are improving. Second, the Fund may invest significantly in securities the prices of which the Adviser believes are more sensitive to events related to the underlying issuer than to changes in general interest rates or overall market default rates. The Adviser believes that the Fund may generate positive returns by having a portion of the Fund’s assets invested in non-market-related securities, rather than by relying primarily on changes in interest rates to produce returns for the Fund. Third, the Adviser analyzes different sectors of the economy and differences in the yields (“spreads”) of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk. The Adviser generally prefers securities that are protected against calls (early redemption by the issuer).

In connection with its principal investment strategies, the Fund may also invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in securities of other foreign issuers, including emerging markets securities. The Fund may also invest in obligations of supranational entities without limit ( e.g. , the World Bank), corporate securities, U.S. government securities, commercial paper, zero-coupon securities, mortgage-backed securities, including mortgage dollar rolls, stripped mortgage-backed securities and collateralized mortgage obligations and other asset-backed securities, when-issued securities, convertible securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”) and structured notes. The Fund may also engage in foreign currency hedging transactions and swap transactions (including credit default swaps) for hedging or investment purposes. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, and swap transactions 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 traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

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

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities.

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

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

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 an unexpected 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. 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.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2009, 12.65%

Lowest Quarterly Return:
Third Quarter 2008, -7.19%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Investment Grade Bond Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class Y	12.25%	8.20%	9.01%
Class Y Return After Taxes on Distributions	10.11%	5.89%	6.61%
Class Y Return After Taxes on Distributions & Sale of Fund Shares	8.11%	5.67%	6.39%
Class A	6.96%	6.95%	8.21%
Class B	6.10%	6.77%	7.82%
Class C	10.15%	7.13%	7.87%
Class N	12.25%	8.20%	9.01%
Admin Class	14.90%	8.19%	8.53%
Barclays U.S. Government/Credit Bond Index	4.82%	6.06%	5.25%

The returns shown in the table for Class A shares prior to September 15, 2003 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class B and Class C shares (September 12, 2003), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B and Class C shares, respectively. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses.

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

[1] Other expenses include an administrative services fee of 0.25% for Admin Class shares.

[2] Other expenses for Class N shares 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 0.95%, 1.70%, 1.70%, 0.65%, 0.70% and 1.20% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 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 0.95%, 1.70%, 1.70%, 0.65%, 0.70% and 1.20% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles International Bond Fund

Loomis Sayles International Bond Fund

Investment Goal

The Fund seeks high total investment return through a combination of high current income and capital appreciation.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles International Bond Fund	Class A	Class C	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	1.00%	none
Redemption fees	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles International Bond Fund		Class A	Class C	Class Y
Management fees		0.60%	0.60%	0.60%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none
Other expenses		1.00%	1.01%	1.00%
Total annual fund operating expenses		1.85%	2.61%	1.60%
Fee waiver and/or expense reimbursement	[1]	0.80%	0.81%	0.80%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.05%	1.80%	0.80%

Example

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

If shares are redeemed:

Expense Example Loomis Sayles International Bond Fund (USD $)	1 year	3 years	5 years	10 years
Class A	552	931	1,334	2,459
Class C	283	735	1,313	2,884
Class Y	82	427	795	1,833

If shares are not redeemed:

Expense Example, No Redemption (USD $)	1 year	3 years	5 years	10 years
Loomis Sayles International Bond Fund Class C	183	735	1,313	2,884

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 169% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund expects to invest at least 80% of its net assets (plus any borrowings made for investment purposes) in fixed-income 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. The Fund invests primarily (at least 65% of its net assets) in fixed-income securities of issuers located outside the United States. Securities held by the Fund may be denominated in any currency and may be of issuers located in emerging market countries. The Fund invests primarily in investment-grade fixed-income securities. “Investment-grade” securities are those securities that are rated as such at the time of purchase by at least one of the three major rating agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)) or, if unrated, are determined by the Adviser to be of comparable quality, although the Fund may invest up to 35% of its assets in below investment-grade fixed-income securities (commonly known as “junk bonds”). There is no minimum rating for securities in which the Fund will invest. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s, Fitch or S&P) have rated the securities in one of its top four ratings categories) or, if unrated, are determined by the Adviser to be of comparable quality. The Fund may invest in fixed-income securities of any maturity. The Fund may also invest in foreign currencies and may engage in other foreign currency transactions for investment or for hedging purposes.

In deciding which securities to buy and sell, the Adviser may consider, among other things, the stability and volatility of a country’s bond markets, the financial strength of the issuer, current interest rates, current valuations, currency considerations, the Adviser’s expectations regarding general trends in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.

Three themes typically drive the Fund’s investment approach. First, the Adviser generally seeks fixed-income securities of issuers whose credit profiles it believes are improving. The Adviser’s credit research team provides deep fundamental and quantitative analysis as well as ratings on over 1,000 credits worldwide. The broad coverage combined with the objective to identify attractive investment opportunities makes this an important component of the investment approach. Second, the Adviser analyzes political, economic, and other fundamental factors and combines this analysis with a comparison of the yield spreads of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk. Third, if a security that is believed to be attractive is denominated in a foreign currency, the Adviser analyzes whether to accept or to hedge the currency risk. In certain instances, the Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

The fixed-income securities in which the Fund may invest include public or private debt obligations issued or guaranteed by U.S. or non-U.S. issuers, including, but not limited to, corporations, governments (including their agencies, instrumentalities and sponsored entities), supranational entities, partnerships and trusts. The Fund may also invest in preferred stocks, convertible securities, when-issued securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), mortgage- or asset-backed securities and zero-coupon securities issued by any of the above-named entities.

In connection with its principal investment strategies, the Fund may also invest in inflation- and index-linked securities, senior loans, structured notes, common stocks (limited to shares acquired as a result of a financial restructuring, bankruptcy or similar transaction or from an exchange or conversion of a permissible security held in the portfolio), and derivatives, including options, futures, options on futures, forward contracts and swap contracts (including credit default swaps). The Fund may also engage in active and frequent trading of securities. Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivatives instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, options and futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

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

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities.

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

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. 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.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

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 an unexpected 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. 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 (“NAV”).

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year and life-of-fund periods compare with those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Third Quarter 2010, 11.59%

Lowest Quarterly Return:
First Quarter 2009, -3.76%

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles International Bond Fund	Past 1 Year	Life of Fund	Inception Date
Class A	2.63%	5.14%	Feb. 01, 2008
Class A Return After Taxes on Distributions	1.35%	3.26%	Feb. 01, 2008
Class A Return After Taxes on Distributions & Sale of Fund Shares	1.87%	3.34%	Feb. 01, 2008
Class C	5.53%	5.31%	Feb. 01, 2008
Class Y	7.69%	6.37%	Feb. 01, 2008
Barclays Global Aggregate ex-USD Bond Index	4.09%	4.43%	Feb. 01, 2008

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

[1] 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% and 0.80% of the Fund's average daily net assets for Class A, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.05%, 1.80% and 0.80% of the Fund's average daily net assets for Class A, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Global Equity and Income Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Global Equity and Income Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment goal is high total investment return through a combination of capital appreciation and current income.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy 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 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	29.00%
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
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in equity and fixed-income securities of U.S. and foreign issuers. Equity securities purchased by the Fund may include common stocks, preferred stocks, depositary receipts, warrants, securities convertible into common or preferred stocks, interests in real estate investment trusts (“REITs”) and/or real estate-related securities and other equity-like interests in an issuer. The Fund will invest a significant portion of its assets outside the U.S., including securities of issuers located in emerging market countries. In deciding which domestic and international equity securities to buy and sell, the Adviser generally looks for companies that it believes have the potential for superior earnings growth relative to their current value. The Adviser also looks for companies that appear to be undervalued relative to the intrinsic value of the companies’ assets or cash flows. In deciding which domestic and international fixed-income securities to buy and sell, the Adviser generally looks for securities that it believes are undervalued and have the potential for credit upgrades, which may include securities that are below investment-grade (also known as “junk bonds”). The Fund may also invest in foreign currencies, collateralized mortgage obligations, zero-coupon securities, when-issued securities, REITs, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”) and mortgage-related securities. The Fund may also engage in active and frequent trading of securities and engage in options or foreign currency transactions for hedging and investment purposes and futures transactions, foreign currency transactions and swap transactions (including credit default swaps). Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. The Adviser may hedge currency risk for the Fund (including “cross hedging” between two or more foreign currencies) if it believes the outlook for a particular foreign currency is unfavorable. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Allocation Risk: The Fund’s investment performance depends on how its assets are allocated. The allocation, as set forth above, may not be optimal in every market condition. You could lose money on your investment in the Fund as a result of this allocation. 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 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives, such as forward currency contracts, options and futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Rule 144A securities may be more illiquid than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. Mortgage-Related Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity and valuation risk), mortgage-related securities are subject to the risks of the mortgages underlying the securities as well as prepayment risk, the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that an unexpected rise in interest rates will extend the life of a mortgage-related security beyond the expected prepayment time, typically reducing the security’s value. The Fund also may incur a loss when there is a prepayment of securities that were purchased at a premium. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class Y Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2009, 19.91% Lowest Quarterly Return: Third Quarter 2008, -19.64%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the table prior to the inception of Class A and Class C shares (February 1, 2006) are those of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class A and Class C shares, respectively. 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-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Global Equity and Income Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.21%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.21%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.21%
1 year	rr_ExpenseExampleYear01	691
3 years	rr_ExpenseExampleYear03	937
5 years	rr_ExpenseExampleYear05	1,202
10 years	rr_ExpenseExampleYear10	1,957
Past 1 Year	rr_AverageAnnualReturnYear01	8.54%
Past 5 Years	rr_AverageAnnualReturnYear05	2.40%
Past 10 Years	rr_AverageAnnualReturnYear10	10.14%
Loomis Sayles Global Equity and Income Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.21%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.96%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.96%
1 year	rr_ExpenseExampleYear01	299
3 years	rr_ExpenseExampleYear03	615
5 years	rr_ExpenseExampleYear05	1,057
10 years	rr_ExpenseExampleYear10	2,285
1 year	rr_ExpenseExampleNoRedemptionYear01	199
3 years	rr_ExpenseExampleNoRedemptionYear03	615
5 years	rr_ExpenseExampleNoRedemptionYear05	1,057
10 years	rr_ExpenseExampleNoRedemptionYear10	2,285
Past 1 Year	rr_AverageAnnualReturnYear01	13.31%
Past 5 Years	rr_AverageAnnualReturnYear05	2.84%
Past 10 Years	rr_AverageAnnualReturnYear10	9.97%
Loomis Sayles Global Equity and Income Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.75%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.21%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.96%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.96%
1 year	rr_ExpenseExampleYear01	98
3 years	rr_ExpenseExampleYear03	306
5 years	rr_ExpenseExampleYear05	531
10 years	rr_ExpenseExampleYear10	1,178
2003	rr_AnnualReturn2003	31.16%
2004	rr_AnnualReturn2004	14.12%
2005	rr_AnnualReturn2005	12.38%
2006	rr_AnnualReturn2006	11.06%
2007	rr_AnnualReturn2007	26.49%
2008	rr_AnnualReturn2008	(39.19%)
2009	rr_AnnualReturn2009	42.52%
2010	rr_AnnualReturn2010	21.69%
2011	rr_AnnualReturn2011	(0.73%)
2012	rr_AnnualReturn2012	15.49%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	19.91%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(19.64%)
Past 1 Year	rr_AverageAnnualReturnYear01	15.49%
Past 5 Years	rr_AverageAnnualReturnYear05	3.87%
Past 10 Years	rr_AverageAnnualReturnYear10	11.07%
Loomis Sayles Global Equity and Income Fund | Return After Taxes on Distributions | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	15.08%
Past 5 Years	rr_AverageAnnualReturnYear05	3.26%
Past 10 Years	rr_AverageAnnualReturnYear10	10.25%
Loomis Sayles Global Equity and Income Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class Y
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	10.37%
Past 5 Years	rr_AverageAnnualReturnYear05	2.99%
Past 10 Years	rr_AverageAnnualReturnYear10	9.41%
Loomis Sayles Global Equity and Income Fund | MSCI World Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	16.54%
Past 5 Years	rr_AverageAnnualReturnYear05	(0.60%)
Past 10 Years	rr_AverageAnnualReturnYear10	8.08%
Loomis Sayles Global Equity and Income Fund | Citigroup World Government Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	1.65%
Past 5 Years	rr_AverageAnnualReturnYear05	5.27%
Past 10 Years	rr_AverageAnnualReturnYear10	6.04%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.25%, 2.00% and 1.00% of the Fund's average daily net assets for Class A, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00% and 1.00% of the Fund's average daily net assets for Class A, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles Global Equity and Income Fund

Loomis Sayles Global Equity and Income Fund

Investment Goal

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

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Global Equity and Income Fund	Class A	Class C	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	1.00%	none
Redemption fees	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Global Equity and Income Fund		Class A	Class C	Class Y
Management fees		0.75%	0.75%	0.75%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none
Other expenses		0.21%	0.21%	0.21%
Total annual fund operating expenses		1.21%	1.96%	0.96%
Fee waiver and/or expense reimbursement	[1]	none	none	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.21%	1.96%	0.96%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If shares are redeemed:

Expense Example Loomis Sayles Global Equity and Income Fund (USD $)	1 year	3 years	5 years	10 years
Class A	691	937	1,202	1,957
Class C	299	615	1,057	2,285
Class Y	98	306	531	1,178

If shares are not redeemed:

Expense Example, No Redemption (USD $)	1 year	3 years	5 years	10 years
Loomis Sayles Global Equity and Income Fund Class C	199	615	1,057	2,285

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 29% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in equity and fixed-income securities of U.S. and foreign issuers. Equity securities purchased by the Fund may include common stocks, preferred stocks, depositary receipts, warrants, securities convertible into common or preferred stocks, interests in real estate investment trusts (“REITs”) and/or real estate-related securities and other equity-like interests in an issuer. The Fund will invest a significant portion of its assets outside the U.S., including securities of issuers located in emerging market countries.

In deciding which domestic and international equity securities to buy and sell, the Adviser generally looks for companies that it believes have the potential for superior earnings growth relative to their current value. The Adviser also looks for companies that appear to be undervalued relative to the intrinsic value of the companies’ assets or cash flows.

In deciding which domestic and international fixed-income securities to buy and sell, the Adviser generally looks for securities that it believes are undervalued and have the potential for credit upgrades, which may include securities that are below investment-grade (also known as “junk bonds”). The Fund may also invest in foreign currencies, collateralized mortgage obligations, zero-coupon securities, when-issued securities, REITs, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”) and mortgage-related securities. The Fund may also engage in active and frequent trading of securities and engage in options or foreign currency transactions for hedging and investment purposes and futures transactions, foreign currency transactions and swap transactions (including credit default swaps). Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. The Adviser may hedge currency risk for the Fund (including “cross hedging” between two or more foreign currencies) if it believes the outlook for a particular foreign currency is unfavorable. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

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

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

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives, such as forward currency contracts, options and futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Rule 144A securities may be more illiquid than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them.

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

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

Mortgage-Related Securities Risk: In addition to the risks associated with investments in fixed-income securities generally (for example, credit, liquidity and valuation risk), mortgage-related securities are subject to the risks of the mortgages underlying the securities as well as prepayment risk, the risk that the securities may be prepaid and result in the reinvestment of the prepaid amounts in securities with lower yields than the prepaid obligations. Conversely, there is a risk that an unexpected rise in interest rates will extend the life of a mortgage-related security beyond the expected prepayment time, typically reducing the security’s value. The Fund also may incur a loss when there is a prepayment of securities that were purchased at a premium.

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.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2009, 19.91%

Lowest Quarterly Return:
Third Quarter 2008, -19.64%

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Global Equity and Income Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class Y	15.49%	3.87%	11.07%
Class Y Return After Taxes on Distributions	15.08%	3.26%	10.25%
Class Y Return After Taxes on Distributions & Sale of Fund Shares	10.37%	2.99%	9.41%
Class A	8.54%	2.40%	10.14%
Class C	13.31%	2.84%	9.97%
MSCI World Index	16.54%	(0.60%)	8.08%
Citigroup World Government Bond Index	1.65%	5.27%	6.04%

The returns shown in the table prior to the inception of Class A and Class C shares (February 1, 2006) are those of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class A and Class C shares, respectively.

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-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.

[1] 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 1.25%, 2.00% and 1.00% of the Fund's average daily net assets for Class A, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00% and 1.00% of the Fund's average daily net assets for Class A, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Limited Term Government and Agency Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Limited Term Government and Agency Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high current return consistent with preservation of capital.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy 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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 56% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	56.00%
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
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in investments issued or guaranteed by the U.S. government, its agencies or instrumentalities. The Adviser follows a total return-oriented investment approach in selecting securities for the Fund. It seeks securities that will provide the Fund with an average credit quality equal to the credit rating of the U.S. Government’s long-term debt and an effective portfolio duration range of two to four years (although not all securities selected will have these characteristics and the Adviser may look for other characteristics if market conditions change). The Fund may invest in securities with credit quality above or below the credit rating of the U.S. Government’s long-term debt. In determining credit quality, the Adviser will look to the highest credit rating assigned by Standard & Poor’s Ratings Group (“S&P”), Fitch Investor Services, Inc. (“Fitch”) or Moody’s Investors Service, Inc. (“Moody’s”). In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments. In selecting investments for the Fund, the Adviser’s research analysts work closely with the Fund’s portfolio managers to develop an outlook on the economy from research produced by various financial firms and specific forecasting services or from economic data released by the U.S. and foreign governments as well as the Federal Reserve Bank. The analysts also conduct a thorough review of individual securities to identify what they consider attractive values in the U.S. government security marketplace through the use of quantitative tools such as internal and external computer systems and software. The Adviser continuously monitors an issuer’s creditworthiness to assess whether the obligation remains an appropriate investment for the Fund. The Adviser seeks to balance opportunities for yield and price performance by combining macroeconomic analysis with individual security selection. It emphasizes securities that tend to perform particularly well in response to interest rate changes, such as U.S. Treasury securities in a declining interest rate environment and mortgage-backed or U.S. government agency securities in a steady or rising interest rate environment. The Adviser seeks to increase the opportunity for higher yields while maintaining the greater price stability that intermediate-term bonds have compared to bonds with longer maturities. In connection with its principal investment strategies, the Fund may also invest in investment-grade corporate notes and bonds, zero-coupon bonds, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), foreign bonds denominated in U.S. dollars, asset-backed securities and mortgage-related securities including mortgage dollar rolls. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Agency Securities Risk: Agency securities are subject to fixed-income securities risk. Certain debt securities issued or guaranteed by agencies of the U.S. government are guaranteed as to the payment of principal and interest by the relevant entity but have not been backed by the full faith and credit of the U.S. government. Instead, they have been supported only by the discretionary authority of the U.S. government to purchase the agency’s obligations. An event affecting the guaranteeing entity could adversely affect the payment of principal or interest or both on the security and, therefore, these types of securities should be considered to be riskier than U.S. government securities. Credit Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities may be more illiquid than other fixed-income securities. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. 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 an unexpected 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. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Third Quarter 2009, 2.93% Lowest Quarterly Return: Second Quarter 2004, -1.76% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The Fund’s current adviser assumed that function on September 1, 2003. Prior to that, it served as subadviser to the Fund, a role it assumed in June 2001. The returns shown in the bar chart and table for periods prior to September 15, 2003 reflect the results of the CDC Nvest Limited Term U.S. Government Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Limited Term Government and Agency Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	3.00%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.20%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.90%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.85%
1 year	rr_ExpenseExampleYear01	384
3 years	rr_ExpenseExampleYear03	574
5 years	rr_ExpenseExampleYear05	779
10 years	rr_ExpenseExampleYear10	1,370
2003	rr_AnnualReturn2003	1.50%
2004	rr_AnnualReturn2004	2.00%
2005	rr_AnnualReturn2005	1.18%
2006	rr_AnnualReturn2006	3.80%
2007	rr_AnnualReturn2007	5.23%
2008	rr_AnnualReturn2008	4.61%
2009	rr_AnnualReturn2009	7.73%
2010	rr_AnnualReturn2010	5.13%
2011	rr_AnnualReturn2011	2.59%
2012	rr_AnnualReturn2012	3.16%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	2.93%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Jun. 30, 2004
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(1.76%)
Past 1 Year	rr_AverageAnnualReturnYear01	0.04%
Past 5 Years	rr_AverageAnnualReturnYear05	4.00%
Past 10 Years	rr_AverageAnnualReturnYear10	3.36%
Loomis Sayles Limited Term Government and Agency Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.20%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.65%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.60%
1 year	rr_ExpenseExampleYear01	663
3 years	rr_ExpenseExampleYear03	815
5 years	rr_ExpenseExampleYear05	1,092
10 years	rr_ExpenseExampleYear10	1,750
1 year	rr_ExpenseExampleNoRedemptionYear01	163
3 years	rr_ExpenseExampleNoRedemptionYear03	515
5 years	rr_ExpenseExampleNoRedemptionYear05	892
10 years	rr_ExpenseExampleNoRedemptionYear10	1,750
Past 1 Year	rr_AverageAnnualReturnYear01	(2.61%)
Past 5 Years	rr_AverageAnnualReturnYear05	3.53%
Past 10 Years	rr_AverageAnnualReturnYear10	2.92%
Loomis Sayles Limited Term Government and Agency Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.20%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.65%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.60%
1 year	rr_ExpenseExampleYear01	263
3 years	rr_ExpenseExampleYear03	515
5 years	rr_ExpenseExampleYear05	892
10 years	rr_ExpenseExampleYear10	1,950
1 year	rr_ExpenseExampleNoRedemptionYear01	163
3 years	rr_ExpenseExampleNoRedemptionYear03	515
5 years	rr_ExpenseExampleNoRedemptionYear05	892
10 years	rr_ExpenseExampleNoRedemptionYear10	1,950
Past 1 Year	rr_AverageAnnualReturnYear01	1.39%
Past 5 Years	rr_AverageAnnualReturnYear05	3.87%
Past 10 Years	rr_AverageAnnualReturnYear10	2.92%
Loomis Sayles Limited Term Government and Agency Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.45%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.20%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.65%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.05%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.60%
1 year	rr_ExpenseExampleYear01	61
3 years	rr_ExpenseExampleYear03	203
5 years	rr_ExpenseExampleYear05	357
10 years	rr_ExpenseExampleYear10	806
Past 1 Year	rr_AverageAnnualReturnYear01	3.41%
Past 5 Years	rr_AverageAnnualReturnYear05	4.90%
Past 10 Years	rr_AverageAnnualReturnYear10	3.94%
Loomis Sayles Limited Term Government and Agency Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	(0.74%)
Past 5 Years	rr_AverageAnnualReturnYear05	2.96%
Past 10 Years	rr_AverageAnnualReturnYear10	2.15%
Loomis Sayles Limited Term Government and Agency Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	0.03%
Past 5 Years	rr_AverageAnnualReturnYear05	2.81%
Past 10 Years	rr_AverageAnnualReturnYear10	2.15%
Loomis Sayles Limited Term Government and Agency Fund | Barclays U.S. 1-5 Year Government Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	0.97%
Past 5 Years	rr_AverageAnnualReturnYear05	3.39%
Past 10 Years	rr_AverageAnnualReturnYear10	3.38%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 0.85%, 1.60%, 1.60% and 0.60% of the Fund's average daily net assets for Class A, B, C 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 January 31, 2014 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 0.85%, 1.60%, 1.60% and 0.60% of the Fund's average daily net assets for Class A, B, C, and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles Growth Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund’s investment goal is long-term growth of capital.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 16% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	16.00%
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
Other Expenses, New Fund, Based on Estimates [Text]	rr_OtherExpensesNewFundBasedOnEstimates	Other expenses for Class N shares are estimated for the current fiscal year.
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks, convertible securities and warrants. The Fund focuses on stocks of large capitalization companies, but the Fund may invest in companies of any size. The Fund normally invests across a wide range of sectors and industries. The Fund’s portfolio manager employs a growth style of equity management that emphasizes companies with sustainable competitive advantages, secular long-term cash flow growth returns on invested capital above their cost of capital and the ability to manage for profitable growth that can create long-term value for shareholders. The Fund’s portfolio manager 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 the issuer’s investment fundamentals are beginning to deteriorate, when the investment no longer appears consistent with the portfolio manager’s investment methodology, when the Fund must meet redemptions, in order to take advantage of more attractive investment opportunities, or for other investment reasons which the portfolio manager deems appropriate. The Fund may also invest any portion of its assets in equity securities of Canadian issuers, up to 20% of its assets in other foreign securities, including emerging market securities, engage in foreign currency transactions, invest in options for hedging and investment purposes and invest in securities issued pursuant to Rule 144 under the securities Act of 1933 (“Rule 144A securities”). The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts and options transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio manager may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Third Quarter 2010, 14.73% Lowest Quarterly Return: Fourth Quarter 2008, -26.00% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Explanation after Tax Higher	rr_PerformanceTableExplanationAfterTaxHigher	The Return After Taxes on Distributions & Sale of Fund Shares for the 5-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 Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the chart and table for Class A shares prior to September 15, 2003 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class B and Class C shares (September 12, 2003), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B shares and Class C shares, respectively. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. The Return After Taxes on Distributions & Sale of Fund Shares for the 5-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles Growth Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.32%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.07%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.07%
1 year	rr_ExpenseExampleYear01	678
3 years	rr_ExpenseExampleYear03	896
5 years	rr_ExpenseExampleYear05	1,131
10 years	rr_ExpenseExampleYear10	1,806
2003	rr_AnnualReturn2003	32.17%
2004	rr_AnnualReturn2004	15.62%
2005	rr_AnnualReturn2005	10.53%
2006	rr_AnnualReturn2006	(3.49%)
2007	rr_AnnualReturn2007	21.88%
2008	rr_AnnualReturn2008	(50.07%)
2009	rr_AnnualReturn2009	32.16%
2010	rr_AnnualReturn2010	15.34%
2011	rr_AnnualReturn2011	0.32%
2012	rr_AnnualReturn2012	18.54%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	14.73%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(26.00%)
Past 1 Year	rr_AverageAnnualReturnYear01	11.82%
Past 5 Years	rr_AverageAnnualReturnYear05	(3.12%)
Past 10 Years	rr_AverageAnnualReturnYear10	5.41%
Loomis Sayles Growth Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.32%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.82%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.82%
1 year	rr_ExpenseExampleYear01	685
3 years	rr_ExpenseExampleYear03	873
5 years	rr_ExpenseExampleYear05	1,185
10 years	rr_ExpenseExampleYear10	1,940
1 year	rr_ExpenseExampleNoRedemptionYear01	185
3 years	rr_ExpenseExampleNoRedemptionYear03	573
5 years	rr_ExpenseExampleNoRedemptionYear05	985
10 years	rr_ExpenseExampleNoRedemptionYear10	1,940
Past 1 Year	rr_AverageAnnualReturnYear01	12.48%
Past 5 Years	rr_AverageAnnualReturnYear05	(3.10%)
Past 10 Years	rr_AverageAnnualReturnYear10	5.24%
Loomis Sayles Growth Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.32%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.82%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.82%
1 year	rr_ExpenseExampleYear01	285
3 years	rr_ExpenseExampleYear03	573
5 years	rr_ExpenseExampleYear05	985
10 years	rr_ExpenseExampleYear10	2,137
1 year	rr_ExpenseExampleNoRedemptionYear01	185
3 years	rr_ExpenseExampleNoRedemptionYear03	573
5 years	rr_ExpenseExampleNoRedemptionYear05	985
10 years	rr_ExpenseExampleNoRedemptionYear10	2,137
Past 1 Year	rr_AverageAnnualReturnYear01	16.71%
Past 5 Years	rr_AverageAnnualReturnYear05	(2.67%)
Past 10 Years	rr_AverageAnnualReturnYear10	5.26%
Loomis Sayles Growth Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.18%	[2]
Total annual fund operating expenses	rr_ExpensesOverAssets	0.68%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.68%
1 year	rr_ExpenseExampleYear01	69
3 years	rr_ExpenseExampleYear03	218
5 years	rr_ExpenseExampleYear05	379
10 years	rr_ExpenseExampleYear10	847
Past 1 Year	rr_AverageAnnualReturnYear01	18.75%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.63%)
Past 10 Years	rr_AverageAnnualReturnYear10	6.40%
Loomis Sayles Growth Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.50%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	0.32%
Total annual fund operating expenses	rr_ExpensesOverAssets	0.82%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	none	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.82%
1 year	rr_ExpenseExampleYear01	84
3 years	rr_ExpenseExampleYear03	262
5 years	rr_ExpenseExampleYear05	455
10 years	rr_ExpenseExampleYear10	1,014
Past 1 Year	rr_AverageAnnualReturnYear01	18.75%
Past 5 Years	rr_AverageAnnualReturnYear05	(1.63%)
Past 10 Years	rr_AverageAnnualReturnYear10	6.40%
Loomis Sayles Growth Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	11.67%
Past 5 Years	rr_AverageAnnualReturnYear05	(3.15%)
Past 10 Years	rr_AverageAnnualReturnYear10	5.39%
Loomis Sayles Growth Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	7.87%
Past 5 Years	rr_AverageAnnualReturnYear05	(2.63%)
Past 10 Years	rr_AverageAnnualReturnYear10	4.74%
Loomis Sayles Growth Fund | Russell 1000 Growth Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	15.26%
Past 5 Years	rr_AverageAnnualReturnYear05	3.12%
Past 10 Years	rr_AverageAnnualReturnYear10	7.52%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.25%, 2.00%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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

XML

Document and Entity Information	12 Months Ended
	Feb. 01, 2013
Risk/Return:
Document Type	485BPOS
Document Period End Date	Sep. 30, 2012
Registrant Name	LOOMIS SAYLES FUNDS II
Central Index Key	0000872649
Amendment Flag	false
Document Creation Date	Jan. 28, 2013
Document Effective Date	Feb. 01, 2013
Prospectus Date	Feb. 01, 2013

XML

Loomis Sayles Mid Cap Growth Fund

Loomis Sayles Mid Cap Growth Fund

Investment Goal

The Fund’s investment objective is long-term capital growth from investments in common stocks or similar securities.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Mid Cap Growth Fund	Class A	Class C	Class N	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	1.00%	none	none
Redemption fees	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Mid Cap Growth Fund		Class A	Class C	Class N		Class Y
Management fees		0.75%	0.75%	0.75%		0.75%
Distribution and/or service (12b-1) fees		0.25%	1.00%	none		none
Other expenses		0.38%	0.38%	0.22%	[1]	0.38%
Total annual fund operating expenses		1.38%	2.13%	0.97%		1.13%
Fee waiver and/or expense reimbursement	[2]	0.13%	0.13%	0.02%		0.13%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.25%	2.00%	0.95%		1.00%

Example

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

If shares are redeemed:

Expense Example Loomis Sayles Mid Cap Growth Fund (USD $)	1 year	3 years	5 years	10 years
Class A	695	975	1,275	2,127
Class C	303	654	1,132	2,452
Class N	97	307	534	1,188
Class Y	102	346	610	1,363

If shares are not redeemed:

Expense Example, No Redemption (USD $)	1 year	3 years	5 years	10 years
Loomis Sayles Mid Cap Growth Fund Class C	203	654	1,132	2,452

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 191% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in common stocks or other equity securities, including preferred stocks, warrants, securities convertible into common or preferred stocks and other equity-like interests in companies whose market capitalization falls within the Russell Midcap Growth Index. While the market capitalization range for this index fluctuates, at December 31, 2012, it was $337 million to $21 billion. The Fund may invest the rest of its assets in companies of any size.

In deciding which securities to buy and sell, the Adviser seeks to identify companies that it believes have distinctive products, technologies or services, dynamic earnings growth, prospects for high levels of profitability and/or solid management. The Adviser typically does not consider current income when making buy/sell decisions.

The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in other foreign securities, including emerging markets securities. The Fund may engage in foreign currency transactions, options for hedging and investment purposes and futures transactions, and may also engage in securities lending. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. The Fund also may invest in securities offered in the secondary markets or in initial public offerings, real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”). The Fund may engage in active and frequent trading of securities. Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts and options and futures transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

Equity Securities Risk: The value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. Securities issued in IPOs tend to involve greater market risk than other equity securities due, in part, to public perception and the lack of publicly available information and trading history. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.

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

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund.

Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Second Quarter 2003, 19.49%

Lowest Quarterly Return:
Third Quarter 2008, -26.07%

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Mid Cap Growth Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class A	6.14%	(1.89%)	9.98%
Class A Return After Taxes on Distributions	6.14%	(1.89%)	9.95%
Class A Return After Taxes on Distributions & Sale of Fund Shares	3.99%	(1.59%)	8.90%
Class C	10.77%	(1.46%)	9.77%
Class N	12.93%	(0.46%)	10.92%
Class Y	12.93%	(0.46%)	10.92%
Russell Midcap Growth Index	15.81%	3.23%	10.32%

The returns shown in the chart and table for Class A shares prior to February 1, 2009 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class C shares (February 2, 2009), performance is that of Retail Class shares, which were redesignated as Class A shares, restated to reflect the higher net expenses and sales loads of Class C shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses. The Fund (formerly, Loomis Sayles Aggressive Growth Fund) changed its name and revised its investment strategies on February 1, 2007. The Fund’s performance may have been different had the current investment strategies been in place for all of the periods shown.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their shares through tax-deferred 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. The Return After Taxes on Distributions & Sale of Fund Shares for the 5-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. Index performance reflects no deduction for fees, expenses or taxes.

[1] Other expenses for Class N shares 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 1.25%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, C, N and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, C, N and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Document Creation Date	dei_DocumentCreationDate	Jan. 28, 2013

XML

Loomis Sayles Strategic Income Fund

Loomis Sayles Strategic Income Fund

Investment Goal

The Fund seeks high current income

with a secondary objective of capital growth.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Strategic Income Fund	Class A	Class B	Class C	Class N	Class Y	Admin Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%	none	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none	none	none
Redemption fees	none	none	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Strategic Income Fund		Class A	Class B	Class C	Class N		Class Y	Admin Class
Management fees		0.56%	0.56%	0.56%	0.56%		0.56%	0.56%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none		none	0.25%
Other expenses	[1][2]	0.15%	0.15%	0.15%	0.06%	[3]	0.15%	0.40%
Total annual fund operating expenses		0.96%	1.71%	1.71%	0.62%		0.71%	1.21%
Fee waiver and/or expense reimbursement	[4]	none	none	none	none		none	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.96%	1.71%	1.71%	0.62%		0.71%	1.21%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If shares are redeemed:

Expense Example Loomis Sayles Strategic Income Fund (USD $)	1 year	3 years	5 years	10 years
Class A	544	742	957	1,575
Class B	674	839	1,128	1,821
Class C	274	539	928	2,019
Class N	63	199	346	774
Class Y	73	227	395	883
Admin Class	123	384	665	1,466

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles Strategic Income Fund (USD $)	1 year	3 years	5 years	10 years
Class B	174	539	928	1,821
Class C	174	539	928	2,019

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 30% the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest substantially all of its assets in income producing securities (including below investment-grade securities, or “junk bonds”) with a focus on U.S. corporate bonds, convertible securities, foreign debt instruments, including those in emerging markets and related foreign currency transactions, and U.S. government securities. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. The Fund may invest up to 35% of its assets in preferred stocks and dividend-paying common stocks. The portfolio managers may shift the Fund’s assets among various types of income-producing securities based upon changing market conditions. The Adviser performs its own extensive credit analyses to determine the creditworthiness and potential for capital appreciation of a security.

The Fund’s portfolio managers use a flexible approach to identify securities in the global marketplace with characteristics including discounted price compared to economic value, undervalued credit ratings with strong or improving credit profiles and yield premium relative to its benchmark (although not all of the securities selected will have these attributes).

In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.

In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser seeks to buy bonds that offer a positive yield advantage over the market and, in its view, have room to increase in price. It may also invest to take advantage of what the portfolio managers believe are temporary disparities in the yield of different segments of the market for U.S. government securities. The Adviser provides the portfolio managers with maximum flexibility to find investment opportunities in a wide range of markets, both domestic and foreign. This flexible approach provides the Fund with access to a wide array of investment opportunities. The three key sectors that the portfolio managers focus upon are U.S. corporate issues (including convertible securities), foreign debt securities and U.S. government securities. The Fund’s portfolio managers maintain a core of the Fund’s investments in corporate bond issues and shift its assets among other income-producing securities as opportunities develop. The Fund generally seeks to maintain a high level of diversification as a form of risk management.

In connection with its principal investment strategies, the Fund may also invest in securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), structured notes, zero-coupon bonds, pay-in-kind bonds, mortgage-related securities, stripped securities and futures, swaps (including credit default swaps) and foreign currency transactions for hedging and investment purposes. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

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

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities.

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

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

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 an unexpected 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. 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.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of two broad measures of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Second Quarter 2009, 18.02%

Lowest Quarterly Return:
Third Quarter 2008, -13.38%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Strategic Income Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class A	9.59%	6.60%	10.06%
Class A Return After Taxes on Distributions	7.73%	4.31%	7.75%
Class A Return After Taxes on Distributions & Sale of Fund Shares	6.33%	4.25%	7.38%
Class B	7.75%	6.23%	9.62%
Class C	11.70%	6.55%	9.63%
Class N	13.93%	7.63%	10.74%
Class Y	13.93%	7.63%	10.74%
Admin Class	13.33%	7.06%	10.13%
Barclays U.S. Aggregate Bond Index	4.21%	5.95%	5.18%
Barclays U.S. Universal Bond Index	5.53%	6.19%	5.59%

The returns shown in the bar chart and table for the periods prior to September 15, 2003 reflect the results of the CDC Nvest Strategic Income Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses.

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

[1] Other expenses include an administrative service fee of 0.25% for Admin Class shares.

[2] The expense information shown in the table above may differ from the expense information disclosed in the Fund's financial highlights table because the financial highlights table reflects the operating expenses of the Fund and does not include acquired fund fees and expenses (expenses indirectly borne by the Fund through investments in certain pooled investment vehicles).

[3] Other expenses for Class N shares are estimated for the current fiscal year.

[4] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.25%, 2.00%, 2.00%, 0.95%, 1.00% and 1.50 % of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 2.00%, 0.95%, 1.00% and 1.50 % of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles High Income Fund

Loomis Sayles High Income Fund

Investment Goal

The Fund seeks high current income plus the opportunity for capital appreciation to produce a high total return.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles High Income Fund	Class A	Class B	Class C	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none
Redemption fees	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles High Income Fund		Class A	Class B	Class C	Class Y
Management fees		0.60%	0.60%	0.60%	0.60%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none
Other expenses		0.34%	0.34%	0.34%	0.35%
Total annual fund operating expenses		1.19%	1.94%	1.94%	0.95%
Fee waiver and/or expense reimbursement	[1]	0.04%	0.04%	0.04%	0.05%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.15%	1.90%	1.90%	0.90%

Example

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

If shares are redeemed:

Expense Example Loomis Sayles High Income Fund (USD $)	1 year	3 years	5 years	10 years
Class A	562	807	1,071	1,825
Class B	693	905	1,243	2,066
Class C	293	605	1,043	2,261
Class Y	92	298	521	1,162

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles High Income Fund (USD $)	1 year	3 years	5 years	10 years
Class B	193	605	1,043	2,066
Class C	193	605	1,043	2,261

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 34% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest at least 65% of its assets in below investment-grade fixed-income securities (commonly known as “junk bonds”). Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. There is no minimum rating for the securities in which the Fund may invest. The Fund will normally invest at least 65% of its assets in U.S. corporate or U.S. dollar-denominated foreign fixed-income securities. The Fund may also invest up to 20% of its assets in foreign currency-denominated fixed-income securities, including those in emerging markets and related currency hedging transactions. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

The Adviser performs its own extensive credit analysis to determine the creditworthiness and potential for capital appreciation of a security. The Fund’s management minimizes both market timing and interest rate forecasting. Instead, it uses a strategy based on gaining a thorough understanding of industry and company dynamics as well as individual security characteristics such as issuer debt and debt maturity schedules, earnings prospects, responsiveness to changes in interest rates, experience and perceived strength of management, borrowing requirements and liquidation value, market price in relation to cash flow, interest and dividends.

In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.

In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser employs a selection strategy that focuses on a value-driven, bottom-up approach to identify securities that provide an opportunity for both generous yields and capital appreciation. The Adviser analyzes an individual company’s potential for positive financial news to determine if it has growth potential. Examples of positive financial news include an upward turn in the business cycle, improvement in cash flows, rising profits or the awarding of new contracts. The Adviser emphasizes in-depth credit analysis, appreciation potential and diversification in its bond selection. Each bond is evaluated to assess the ability of its issuer to pay interest and, ultimately, principal (which helps the Fund generate an ongoing flow of income). The Adviser also assesses a bond’s relation to market conditions within its industry and favors bonds whose prices may benefit from positive business developments. The Adviser seeks to diversify the Fund’s holdings to reduce the inherent risk in below investment-grade fixed-income securities.

In connection with its principal investment strategies, the Fund may also invest in structured notes, zero-coupon securities, pay-in-kind securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), futures and swaps (including credit default swaps). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations.

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities.

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

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Second Quarter 2009, 16.38%

Lowest Quarterly Return:
Fourth Quarter 2008, -18.10%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles High Income Fund	Past 1 Year	Past 5 Years	Past 10 Years	Life of Class Y	Inception Date
Class A	16.25%	7.15%	9.31%
Class A Return After Taxes on Distributions	14.00%	4.18%	6.48%
Class A Return After Taxes on Distributions & Sale of Fund Shares	10.58%	4.38%	6.38%
Class B	15.37%	7.03%	8.98%
Class C	19.69%	7.39%	9.00%
Class Y	21.70%			8.97%	Feb. 29, 2008
Barclays U.S. Corporate High-Yield Bond Index	15.81%	10.34%	10.62%	11.33%

The returns shown in the bar chart and table for the periods prior to September 15, 2003 reflect the results of the CDC Nvest High Income Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003.

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

[1] 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 1.15%, 1.90%, 1.90% and 0.90% of the Fund's average daily net assets for Class A, B, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.15%, 1.90%, 1.90% and 0.90% of the Fund's average daily net assets for Class A, B, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles Value Fund

Loomis Sayles Value Fund

Investment Goal

The Fund’s investment objective is long-term growth of capital and income.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Value Fund	Class A	Class B	Class C	Class N	Class Y	Admin Class
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%	none	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none	none	none
Redemption fees	none	none	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Value Fund		Class A	Class B	Class C	Class N		Class Y	Admin Class
Management fees		0.50%	0.50%	0.50%	0.50%		0.50%	0.50%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none		none	0.25%
Other expenses		0.23%	0.23%	0.23%	0.08%	[1]	0.23%	0.49%	[2]
Total annual fund operating expenses		0.98%	1.73%	1.73%	0.58%		0.73%	1.24%
Fee waiver and/or expense reimbursement	[3]	none	none	none	none		none	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.98%	1.73%	1.73%	0.58%		0.73%	1.24%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If shares are redeemed:

Expense Example Loomis Sayles Value Fund (USD $)	1 year	3 years	5 years	10 years
Class A	669	869	1,086	1,707
Class B	676	845	1,139	1,842
Class C	276	545	939	2,041
Class N	59	186	324	726
Class Y	75	233	406	906
Admin Class	126	393	681	1,500

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles Value Fund (USD $)	1 year	3 years	5 years	10 years
Class B	176	545	939	1,842
Class C	176	545	939	2,041

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 25% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

Under normal market conditions, the Fund will invest primarily in equity securities, including common stocks, convertible securities and warrants.

In deciding which securities to buy and sell, the Adviser generally looks for companies that it believes are undervalued by the market in relation to earnings, dividends, assets and/or growth prospects. The Fund’s investments may include companies that have suffered significant business problems but that the Adviser believes have favorable prospects for recovery. The Adviser seeks to identify companies that it believes are, among other things, attractively valued based on the Adviser’s estimate of intrinsic value. The Adviser generally seeks to find value by selecting individual stocks that it believes are attractive, rather than by attempting to achieve investment growth by rotating the Fund’s holdings among various sectors of the economy.

The Fund may also invest up to 20% of its assets in securities of foreign issuers including emerging market securities, invest in options for hedging and investment purposes, real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as options transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Value stocks can perform differently from the market as a whole and from other types of stocks. Value stocks also present the risk that their lower valuations fairly reflect their business prospects and that investors will not agree that the stocks represent favorable investment opportunities, and they may fall out of favor with investors and underperform growth stocks during any given period. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.

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

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

REITs Risk: Investments in the real estate industry, including REITs, are particularly sensitive to economic downturns and are sensitive to factors such as changes in real estate values, property taxes and tax laws, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use and rents and the management skill and creditworthiness of the issuer. Companies in the real estate industry also may be subject to liabilities under environmental and hazardous waste laws. In addition, the value of a REIT is affected by changes in the value of the properties owned by the REIT or mortgage loans held by the REIT. REITs are also subject to default and prepayment risk. Many REITs are highly leveraged, increasing their risk. The Fund will indirectly bear its proportionate share of expenses, including management fees, paid by each REIT in which it invests in addition to the expenses of the Fund.

Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class Y Shares

Highest Quarterly Return:
Second Quarter 2003, 18.11%

Lowest Quarterly Return:
Fourth Quarter 2008, -19.58%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Value Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class Y	19.70%	0.85%	8.52%
Class Y Return After Taxes on Distributions	19.42%	0.62%	8.02%
Class Y Return After Taxes on Distributions & Sale of Fund Shares	13.18%	0.69%	7.43%
Class A	12.52%	(0.62%)	7.57%
Class B	13.59%	(0.58%)	7.33%
Class C	17.49%	(0.18%)	7.33%
Class N	19.70%	0.85%	8.52%
Admin Class	19.04%	0.30%	7.92%
Russell 1000 Value Index	17.51%	0.59%	7.38%

The returns shown in the table for Class A shares prior to June 1, 2007 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Retail Class shares (June 30, 2006), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class A shares. Prior to the inception of Class B and Class C shares (June 1, 2007), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B and Class C shares, respectively. Prior to the inception of Admin Class shares (February 1, 2010), performance is that of Class A shares, restated to reflect the higher net expenses of Admin Class shares. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses.

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-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.

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

[2] Other expenses include an administrative services fee of 0.25% for Admin Class shares.

[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 1.10%, 1.85%, 1.85%, 0.80%, 0.85% and 1.35% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.10%, 1.85%, 1.85%, 0.80%, 0.85% and 1.35% of the Fund's average daily net assets for Class A, B, C, N, Y and Admin Class shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles International Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles International Bond Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high total investment return through a combination of high current income and capital appreciation.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 169% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	169.00%
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
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund expects to invest at least 80% of its net assets (plus any borrowings made for investment purposes) in fixed-income 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. The Fund invests primarily (at least 65% of its net assets) in fixed-income securities of issuers located outside the United States. Securities held by the Fund may be denominated in any currency and may be of issuers located in emerging market countries. The Fund invests primarily in investment-grade fixed-income securities. “Investment-grade” securities are those securities that are rated as such at the time of purchase by at least one of the three major rating agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)) or, if unrated, are determined by the Adviser to be of comparable quality, although the Fund may invest up to 35% of its assets in below investment-grade fixed-income securities (commonly known as “junk bonds”). There is no minimum rating for securities in which the Fund will invest. Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s, Fitch or S&P) have rated the securities in one of its top four ratings categories) or, if unrated, are determined by the Adviser to be of comparable quality. The Fund may invest in fixed-income securities of any maturity. The Fund may also invest in foreign currencies and may engage in other foreign currency transactions for investment or for hedging purposes. In deciding which securities to buy and sell, the Adviser may consider, among other things, the stability and volatility of a country’s bond markets, the financial strength of the issuer, current interest rates, current valuations, currency considerations, the Adviser’s expectations regarding general trends in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments. Three themes typically drive the Fund’s investment approach. First, the Adviser generally seeks fixed-income securities of issuers whose credit profiles it believes are improving. The Adviser’s credit research team provides deep fundamental and quantitative analysis as well as ratings on over 1,000 credits worldwide. The broad coverage combined with the objective to identify attractive investment opportunities makes this an important component of the investment approach. Second, the Adviser analyzes political, economic, and other fundamental factors and combines this analysis with a comparison of the yield spreads of various fixed-income securities in an effort to find securities that it believes may produce attractive returns for the Fund in comparison to their risk. Third, if a security that is believed to be attractive is denominated in a foreign currency, the Adviser analyzes whether to accept or to hedge the currency risk. In certain instances, the Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. The fixed-income securities in which the Fund may invest include public or private debt obligations issued or guaranteed by U.S. or non-U.S. issuers, including, but not limited to, corporations, governments (including their agencies, instrumentalities and sponsored entities), supranational entities, partnerships and trusts. The Fund may also invest in preferred stocks, convertible securities, when-issued securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), mortgage- or asset-backed securities and zero-coupon securities issued by any of the above-named entities. In connection with its principal investment strategies, the Fund may also invest in inflation- and index-linked securities, senior loans, structured notes, common stocks (limited to shares acquired as a result of a financial restructuring, bankruptcy or similar transaction or from an exchange or conversion of a permissible security held in the portfolio), and derivatives, including options, futures, options on futures, forward contracts and swap contracts (including credit default swaps). The Fund may also engage in active and frequent trading of securities. Frequent trading may produce high transaction costs and a high level of taxable capital gains, which may lower the Fund’s return. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivatives instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, options and futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Equity Securities Risk: The value of the Fund’s investments in equity securities could be subject to unpredictable declines in the value of individual securities and periods of below-average performance in individual securities or in the equity market as a whole. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. 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. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions. 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 an unexpected 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. 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 (“NAV”).
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
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 (“NAV”).
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year and life-of-fund periods compare with those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year and life-of-fund periods compare with those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Third Quarter 2010, 11.59% Lowest Quarterly Return: First Quarter 2009, -3.76%
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles International Bond Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	1.00%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.85%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.80%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.05%
1 year	rr_ExpenseExampleYear01	552
3 years	rr_ExpenseExampleYear03	931
5 years	rr_ExpenseExampleYear05	1,334
10 years	rr_ExpenseExampleYear10	2,459
2009	rr_AnnualReturn2009	17.28%
2010	rr_AnnualReturn2010	6.84%
2011	rr_AnnualReturn2011	4.41%
2012	rr_AnnualReturn2012	7.43%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2010
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	11.59%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2009
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.76%)
Past 1 Year	rr_AverageAnnualReturnYear01	2.63%
Life of Fund	rr_AverageAnnualReturnSinceInception	5.14%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008
Loomis Sayles International Bond Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	1.01%
Total annual fund operating expenses	rr_ExpensesOverAssets	2.61%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.81%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.80%
1 year	rr_ExpenseExampleYear01	283
3 years	rr_ExpenseExampleYear03	735
5 years	rr_ExpenseExampleYear05	1,313
10 years	rr_ExpenseExampleYear10	2,884
1 year	rr_ExpenseExampleNoRedemptionYear01	183
3 years	rr_ExpenseExampleNoRedemptionYear03	735
5 years	rr_ExpenseExampleNoRedemptionYear05	1,313
10 years	rr_ExpenseExampleNoRedemptionYear10	2,884
Past 1 Year	rr_AverageAnnualReturnYear01	5.53%
Life of Fund	rr_AverageAnnualReturnSinceInception	5.31%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008
Loomis Sayles International Bond Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	none
Other expenses	rr_OtherExpensesOverAssets	1.00%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.60%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.80%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.80%
1 year	rr_ExpenseExampleYear01	82
3 years	rr_ExpenseExampleYear03	427
5 years	rr_ExpenseExampleYear05	795
10 years	rr_ExpenseExampleYear10	1,833
Past 1 Year	rr_AverageAnnualReturnYear01	7.69%
Life of Fund	rr_AverageAnnualReturnSinceInception	6.37%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008
Loomis Sayles International Bond Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	1.35%
Life of Fund	rr_AverageAnnualReturnSinceInception	3.26%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008
Loomis Sayles International Bond Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	1.87%
Life of Fund	rr_AverageAnnualReturnSinceInception	3.34%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008
Loomis Sayles International Bond Fund | Barclays Global Aggregate ex-USD Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	4.09%
Life of Fund	rr_AverageAnnualReturnSinceInception	4.43%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 01, 2008

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.05%, 1.80% and 0.80% of the Fund's average daily net assets for Class A, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.05%, 1.80% and 0.80% of the Fund's average daily net assets for Class A, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	LOOMIS SAYLES FUNDS II
Prospectus Date	rr_ProspectusDate	Feb. 01, 2013
Loomis Sayles High Income Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Loomis Sayles High Income Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Goal
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks high current income plus the opportunity for capital appreciation to produce a high total return.
Expense [Heading]	rr_ExpenseHeading	Fund Fees & Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses that you may pay if you buy 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 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	January 31, 2014
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	Portfolio Turnover
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 34% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	34.00%
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
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same, except that the example is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Expense Example by, Year, Caption [Text]	rr_ExpenseExampleByYearCaption	If shares are redeemed:
Expense Example, No Redemption, By Year, Caption [Text]	rr_ExpenseExampleNoRedemptionByYearCaption	If shares are not redeemed:
Strategy [Heading]	rr_StrategyHeading	Investments, Risks and Performance Principal Investment Strategies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	Under normal market conditions, the Fund will invest at least 65% of its assets in below investment-grade fixed-income securities (commonly known as “junk bonds”). Below investment-grade fixed-income securities are rated below investment-grade quality ( i.e. , none of the three major ratings agencies (Moody’s Investors Service, Inc. (“Moody’s”), Fitch Investors Services, Inc. (“Fitch”) or Standard and Poor’s Ratings Group (“S&P”)), have rated the securities in one of its top four rating categories) or, if the security is unrated, are determined by the Adviser to be of comparable quality. There is no minimum rating for the securities in which the Fund may invest. The Fund will normally invest at least 65% of its assets in U.S. corporate or U.S. dollar-denominated foreign fixed-income securities. The Fund may also invest up to 20% of its assets in foreign currency-denominated fixed-income securities, including those in emerging markets and related currency hedging transactions. The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. The Adviser performs its own extensive credit analysis to determine the creditworthiness and potential for capital appreciation of a security. The Fund’s management minimizes both market timing and interest rate forecasting. Instead, it uses a strategy based on gaining a thorough understanding of industry and company dynamics as well as individual security characteristics such as issuer debt and debt maturity schedules, earnings prospects, responsiveness to changes in interest rates, experience and perceived strength of management, borrowing requirements and liquidation value, market price in relation to cash flow, interest and dividends. In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments. In selecting investments for the Fund, the Adviser utilizes the skills of its in-house team of more than 30 research analysts to cover a broad universe of industries, companies and markets. The Fund’s portfolio managers take advantage of these extensive resources to identify securities that meet the Fund’s investment criteria. The Adviser employs a selection strategy that focuses on a value-driven, bottom-up approach to identify securities that provide an opportunity for both generous yields and capital appreciation. The Adviser analyzes an individual company’s potential for positive financial news to determine if it has growth potential. Examples of positive financial news include an upward turn in the business cycle, improvement in cash flows, rising profits or the awarding of new contracts. The Adviser emphasizes in-depth credit analysis, appreciation potential and diversification in its bond selection. Each bond is evaluated to assess the ability of its issuer to pay interest and, ultimately, principal (which helps the Fund generate an ongoing flow of income). The Adviser also assesses a bond’s relation to market conditions within its industry and favors bonds whose prices may benefit from positive business developments. The Adviser seeks to diversify the Fund’s holdings to reduce the inherent risk in below investment-grade fixed-income securities. In connection with its principal investment strategies, the Fund may also invest in structured notes, zero-coupon securities, pay-in-kind securities, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), futures and swaps (including credit default swaps). Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The principal risks of investing in the Fund are summarized below. The Fund does not represent a complete investment program. You may lose money by investing in the Fund. Below Investment-Grade Fixed-Income Securities Risk: The Fund’s investments in below investment-grade fixed-income securities, also known as “junk bonds,” may be subject to greater risks than other fixed-income securities, including being subject to greater levels of interest rate risk, credit 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 Risk: Credit risk is the risk that the issuer or the guarantor of a fixed-income security, or the counterparty to a derivatives or other transaction, will be unable or unwilling to make timely payments of interest or principal or to otherwise honor its obligations. Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts, structured notes, futures transactions and swap transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts, swaps and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets. Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Below investment-grade fixed-income securities may be subject to these risks (including the risk of default) to a greater extent than other fixed-income securities. Rule 144A securities and structured notes may be more illiquid than other fixed-income securities. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. The Fund’s investments in foreign securities are also subject to foreign currency fluctuations. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities. Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services. 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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful. Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value. Management Risk: A strategy used by the Fund’s portfolio managers may fail to produce the intended result. Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose money by investing in the Fund.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Risk/Return Bar Chart and Table
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478. The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund’s shares. A sales charge will reduce your return.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-225-5478
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	ngam.natixis.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	The Fund's past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Total Returns for Class A Shares
Bar Chart Does Not Reflect Sales Loads [Text]	rr_BarChartDoesNotReflectSalesLoads	The chart does not reflect any sales charge that you may be required to pay when you buy or redeem the Fund's shares. A sales charge will reduce your return.
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Highest Quarterly Return: Second Quarter 2009, 16.38% Lowest Quarterly Return: Fourth Quarter 2008, -18.10% Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns (for the periods ended December 31, 2012)
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	After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts.
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	The returns shown in the bar chart and table for the periods prior to September 15, 2003 reflect the results of the CDC Nvest High Income Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003. After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.
Loomis Sayles High Income Fund | Class A
Risk/Return:	rr_RiskReturnAbstract
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	4.50%
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other expenses	rr_OtherExpensesOverAssets	0.34%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.19%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.04%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.15%
1 year	rr_ExpenseExampleYear01	562
3 years	rr_ExpenseExampleYear03	807
5 years	rr_ExpenseExampleYear05	1,071
10 years	rr_ExpenseExampleYear10	1,825
2003	rr_AnnualReturn2003	27.91%
2004	rr_AnnualReturn2004	10.35%
2005	rr_AnnualReturn2005	5.04%
2006	rr_AnnualReturn2006	13.86%
2007	rr_AnnualReturn2007	1.98%
2008	rr_AnnualReturn2008	(26.62%)
2009	rr_AnnualReturn2009	50.35%
2010	rr_AnnualReturn2010	13.69%
2011	rr_AnnualReturn2011	(2.98%)
2012	rr_AnnualReturn2012	21.65%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Highest Quarterly Return:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Jun. 30, 2009
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	16.38%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Lowest Quarterly Return:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2008
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(18.10%)
Past 1 Year	rr_AverageAnnualReturnYear01	16.25%
Past 5 Years	rr_AverageAnnualReturnYear05	7.15%
Past 10 Years	rr_AverageAnnualReturnYear10	9.31%
Life of Class Y	rr_AverageAnnualReturnSinceInception
Loomis Sayles High Income Fund | Class B
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	5.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.34%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.94%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.04%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.90%
1 year	rr_ExpenseExampleYear01	693
3 years	rr_ExpenseExampleYear03	905
5 years	rr_ExpenseExampleYear05	1,243
10 years	rr_ExpenseExampleYear10	2,066
1 year	rr_ExpenseExampleNoRedemptionYear01	193
3 years	rr_ExpenseExampleNoRedemptionYear03	605
5 years	rr_ExpenseExampleNoRedemptionYear05	1,043
10 years	rr_ExpenseExampleNoRedemptionYear10	2,066
Past 1 Year	rr_AverageAnnualReturnYear01	15.37%
Past 5 Years	rr_AverageAnnualReturnYear05	7.03%
Past 10 Years	rr_AverageAnnualReturnYear10	8.98%
Life of Class Y	rr_AverageAnnualReturnSinceInception
Loomis Sayles High Income Fund | Class C
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	1.00%
Redemption fees	rr_RedemptionFeeOverRedemption	none
Management fees	rr_ManagementFeesOverAssets	0.60%
Distribution and/or service (12b-1) fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other expenses	rr_OtherExpensesOverAssets	0.34%
Total annual fund operating expenses	rr_ExpensesOverAssets	1.94%
Fee waiver and/or expense reimbursement	rr_FeeWaiverOrReimbursementOverAssets	0.04%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	1.90%
1 year	rr_ExpenseExampleYear01	293
3 years	rr_ExpenseExampleYear03	605
5 years	rr_ExpenseExampleYear05	1,043
10 years	rr_ExpenseExampleYear10	2,261
1 year	rr_ExpenseExampleNoRedemptionYear01	193
3 years	rr_ExpenseExampleNoRedemptionYear03	605
5 years	rr_ExpenseExampleNoRedemptionYear05	1,043
10 years	rr_ExpenseExampleNoRedemptionYear10	2,261
Past 1 Year	rr_AverageAnnualReturnYear01	19.69%
Past 5 Years	rr_AverageAnnualReturnYear05	7.39%
Past 10 Years	rr_AverageAnnualReturnYear10	9.00%
Life of Class Y	rr_AverageAnnualReturnSinceInception
Loomis Sayles High Income Fund | Class Y
Risk/Return:	rr_RiskReturnAbstract
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_MaximumDeferredSalesChargeOverOfferingPrice	none
Redemption fees	rr_RedemptionFeeOverRedemption	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	0.05%	[1]
Total annual fund operating expenses after fee waiver and/or expense reimbursement	rr_NetExpensesOverAssets	0.90%
1 year	rr_ExpenseExampleYear01	92
3 years	rr_ExpenseExampleYear03	298
5 years	rr_ExpenseExampleYear05	521
10 years	rr_ExpenseExampleYear10	1,162
Past 1 Year	rr_AverageAnnualReturnYear01	21.70%
Past 5 Years	rr_AverageAnnualReturnYear05
Past 10 Years	rr_AverageAnnualReturnYear10
Life of Class Y	rr_AverageAnnualReturnSinceInception	8.97%
Inception Date	rr_AverageAnnualReturnInceptionDate	Feb. 29, 2008
Loomis Sayles High Income Fund | Return After Taxes on Distributions | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	14.00%
Past 5 Years	rr_AverageAnnualReturnYear05	4.18%
Past 10 Years	rr_AverageAnnualReturnYear10	6.48%
Life of Class Y	rr_AverageAnnualReturnSinceInception
Loomis Sayles High Income Fund | Return After Taxes on Distributions & Sale of Fund Shares | Class A
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	10.58%
Past 5 Years	rr_AverageAnnualReturnYear05	4.38%
Past 10 Years	rr_AverageAnnualReturnYear10	6.38%
Life of Class Y	rr_AverageAnnualReturnSinceInception
Loomis Sayles High Income Fund | Barclays U.S. Corporate High-Yield Bond Index
Risk/Return:	rr_RiskReturnAbstract
Past 1 Year	rr_AverageAnnualReturnYear01	15.81%
Past 5 Years	rr_AverageAnnualReturnYear05	10.34%
Past 10 Years	rr_AverageAnnualReturnYear10	10.62%
Life of Class Y	rr_AverageAnnualReturnSinceInception	11.33%

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 1.15%, 1.90%, 1.90% and 0.90% of the Fund's average daily net assets for Class A, B, C 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.15%, 1.90%, 1.90% and 0.90% of the Fund's average daily net assets for Class A, B, C and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles Growth Fund

Loomis Sayles Growth Fund

Investment Goal

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

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 34 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Growth Fund	Class A	Class B	Class C	Class N	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	5.75%	none	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none	none
Redemption fees	none	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Growth Fund		Class A	Class B	Class C	Class N		Class Y
Management fees		0.50%	0.50%	0.50%	0.50%		0.50%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none		none
Other expenses		0.32%	0.32%	0.32%	0.18%	[1]	0.32%
Total annual fund operating expenses		1.07%	1.82%	1.82%	0.68%		0.82%
Fee waiver and/or expense reimbursement	[2]	none	none	none	none		none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		1.07%	1.82%	1.82%	0.68%		0.82%

Example

This example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods (except where indicated). The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

If shares are redeemed:

Expense Example Loomis Sayles Growth Fund (USD $)	1 year	3 years	5 years	10 years
Class A	678	896	1,131	1,806
Class B	685	873	1,185	1,940
Class C	285	573	985	2,137
Class N	69	218	379	847
Class Y	84	262	455	1,014

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles Growth Fund (USD $)	1 year	3 years	5 years	10 years
Class B	185	573	985	1,940
Class C	185	573	985	2,137

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 16% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

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

The Fund normally invests across a wide range of sectors and industries. The Fund’s portfolio manager employs a growth style of equity management that emphasizes companies with sustainable competitive advantages, secular long-term cash flow growth returns on invested capital above their cost of capital and the ability to manage for profitable growth that can create long-term value for shareholders. The Fund’s portfolio manager 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 the issuer’s investment fundamentals are beginning to deteriorate, when the investment no longer appears consistent with the portfolio manager’s investment methodology, when the Fund must meet redemptions, in order to take advantage of more attractive investment opportunities, or for other investment reasons which the portfolio manager deems appropriate.

The Fund may also invest any portion of its assets in equity securities of Canadian issuers, up to 20% of its assets in other foreign securities, including emerging market securities, engage in foreign currency transactions, invest in options for hedging and investment purposes and invest in securities issued pursuant to Rule 144 under the securities Act of 1933 (“Rule 144A securities”). The Adviser may elect not to hedge currency risk, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

Currency Risk: Fluctuations in the exchange rates between different currencies may negatively affect an investment. The Fund may elect not to hedge currency risk, or may hedge such risk imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.

Derivatives Risk: Derivative instruments (such as those in which the Fund may invest) can be used to acquire or to transfer the risk and returns of a security or other asset without buying or selling the security or asset. Derivatives are subject to changes in the value of the underlying asset or indices on which such transactions are based. There is no guarantee that the use of derivatives will be effective or that suitable transactions will be available. Even a small investment in derivatives may give rise to leverage risk and can have a significant impact on the Fund’s exposure to securities markets values, interest rates or currency exchange rates. It is possible that the Fund’s liquid assets may be insufficient to support its obligations under its derivatives positions. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used. The Fund’s use of derivatives such as forward currency contracts and options transactions involves other risks, such as the credit risk relating to the other party to a derivative contract (which is greater for forward currency contracts and other over-the-counter traded derivatives), the risk of difficulties in pricing and valuation, the risk that changes in the value of a derivative may not correlate perfectly with 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. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund.

Emerging Markets Risk: Investing in emerging markets companies, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in companies in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more 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. Rule 144A securities may be less liquid than other equity securities. Growth stocks are generally more sensitive to market movements than other types of stocks primarily because their stock prices are based heavily on future expectations. If the Adviser’s assessment of the prospects for a company’s growth is wrong, or if the Adviser’s judgment of how other investors will value the company’s growth is wrong, then the price of the company’s stock may fall or not approach the value that the Adviser has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.

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

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

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. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. The use of leverage increases the impact of gains and losses on a fund’s returns, and may lead to significant losses if investments are not successful.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

Small Capitalization Risk: The general risks associated with corporate income-producing securities are particularly pronounced for securities issued by companies with smaller market capitalizations. These companies may have limited product lines, markets or financial resources or they may depend on a few key employees. As a result, they may be subject to greater levels of credit, market and issuer risk. Securities of smaller companies may trade less frequently and in lesser volume than more widely-held securities and their values may fluctuate more sharply than other securities. Further, securities of smaller companies may perform differently in different cycles than securities of larger companies. Companies with medium-sized market capitalizations may have risks similar to those of smaller companies.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Third Quarter 2010, 14.73%

Lowest Quarterly Return:
Fourth Quarter 2008, -26.00%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Growth Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class A	11.82%	(3.12%)	5.41%
Class A Return After Taxes on Distributions	11.67%	(3.15%)	5.39%
Class A Return After Taxes on Distributions & Sale of Fund Shares	7.87%	(2.63%)	4.74%
Class B	12.48%	(3.10%)	5.24%
Class C	16.71%	(2.67%)	5.26%
Class N	18.75%	(1.63%)	6.40%
Class Y	18.75%	(1.63%)	6.40%
Russell 1000 Growth Index	15.26%	3.12%	7.52%

The returns shown in the chart and table for Class A shares prior to September 15, 2003 are those of Retail Class shares, which were redesignated as Class A shares, restated to reflect the sales loads of Class A shares. Prior to the inception of Class B and Class C shares (September 12, 2003), performance is that of Institutional Class shares, which were redesignated as Class Y shares, restated to reflect the higher net expenses and sales loads of Class B shares and Class C shares, respectively. Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of Class Y shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Class Y shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Class Y shares because Class Y shares are subject to higher expenses.

After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their Fund shares through tax-deferred arrangements, such as 401(k) plans, qualified plans, education savings accounts, such as 529 plans, or individual retirement accounts. The after-tax returns are shown for only one class of the Fund. The Return After Taxes on Distributions & Sale of Fund Shares for the 5-year period exceeds the Return Before Taxes due to an assumed tax benefit from losses on a sale of Fund shares at the end of the measurement period. After-tax returns for the other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses, or taxes.

[1] Other expenses for Class N shares 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 1.25%, 2.00%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.25%, 2.00%, 2.00%, 0.95% and 1.00% of the Fund's average daily net assets for Class A, B, C, N and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles Limited Term Government and Agency Fund

Loomis Sayles Limited Term Government and Agency Fund

Investment Goal

The Fund seeks high current return consistent with preservation of capital.

Fund Fees & Expenses

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the Natixis Fund Complex. More information about these and other discounts is available from your financial professional and in the section “How Sales Charges Are Calculated” on page 55 of the Prospectus and on page 110 in the section “Reduced Sales Charges” of the Statement of Additional Information (“SAI”).

Shareholder Fees
(fees paid directly from your investment)

Shareholder Fees Loomis Sayles Limited Term Government and Agency Fund	Class A	Class B	Class C	Class Y
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	3.00%	none	none	none
Maximum deferred sales charge (load) (as a percentage of original purchase price or redemption proceeds, as applicable)	none	5.00%	1.00%	none
Redemption fees	none	none	none	none

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

Annual Fund Operating Expenses Loomis Sayles Limited Term Government and Agency Fund		Class A	Class B	Class C	Class Y
Management fees		0.45%	0.45%	0.45%	0.45%
Distribution and/or service (12b-1) fees		0.25%	1.00%	1.00%	none
Other expenses		0.20%	0.20%	0.20%	0.20%
Total annual fund operating expenses		0.90%	1.65%	1.65%	0.65%
Fee waiver and/or expense reimbursement	[1]	0.05%	0.05%	0.05%	0.05%
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.85%	1.60%	1.60%	0.60%

Example

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

If shares are redeemed:

Expense Example Loomis Sayles Limited Term Government and Agency Fund (USD $)	1 year	3 years	5 years	10 years
Class A	384	574	779	1,370
Class B	663	815	1,092	1,750
Class C	263	515	892	1,950
Class Y	61	203	357	806

If shares are not redeemed:

Expense Example, No Redemption Loomis Sayles Limited Term Government and Agency Fund (USD $)	1 year	3 years	5 years	10 years
Class B	163	515	892	1,750
Class C	163	515	892	1,950

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 56% of the average value of its portfolio.

Investments, Risks and Performance

Principal Investment Strategies

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

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

In deciding which securities to buy and sell, the Adviser will consider, among other things, the financial strength of the issuer, current interest rates, current valuations, the Adviser’s expectations regarding future changes in interest rates and comparisons of the level of risk associated with particular investments with the Adviser’s expectations concerning the potential return of those investments.

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

In connection with its principal investment strategies, the Fund may also invest in investment-grade corporate notes and bonds, zero-coupon bonds, securities issued pursuant to Rule 144 under the Securities Act of 1933 (“Rule 144A securities”), foreign bonds denominated in U.S. dollars, asset-backed securities and mortgage-related securities including mortgage dollar rolls. Except as provided above, the Fund is not limited in the percentage of its assets that it may invest in these instruments.

Principal Risks

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

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

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

Fixed-Income Securities Risk: Fixed-income securities are subject to credit risk, interest rate risk and liquidity risk. You may lose money on your investment due to unpredictable drops in a security’s value or periods of below-average performance in a given security or in the securities market as a whole. In addition, an economic downturn or period of rising interest rates could adversely affect the market of these securities and reduce the Fund’s ability to sell them. Zero-coupon bonds may be subject to these risks to a greater extent than other fixed-income securities. Rule 144A securities may be more illiquid than other fixed-income securities.

Foreign Securities Risk: Investments in foreign securities may be subject to greater political, economic, environmental, credit and information risks. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity.

Interest Rate Risk: Changes in interest rates may cause the value of the Fund’s investments to decrease. Generally, the value of fixed-income securities rises when prevailing interest rates fall and falls when interest rates rise. A prolonged period of low interest rates may cause the Fund to have a low or negative yield, potentially reducing the value of your investment. The value of zero-coupon bonds may be more sensitive to fluctuations in interest rates than other fixed income securities.

Issuer Risk: The value of the Fund’s investments may decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

Liquidity Risk: Liquidity risk exists when particular investments are difficult to purchase or sell, possibly preventing the Fund from selling these illiquid securities at an advantageous price or time. A lack of liquidity also may cause the value of investments to decline. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Illiquid investments also may be difficult to value.

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

Market Risk: The market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

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 an unexpected 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. 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.

Risk/Return Bar Chart and Table

The bar chart and table shown below provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year-to-year and by showing how the Fund’s average annual returns for the one-year, five-year and ten-year periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at ngam.natixis.com and/or by calling the Fund toll-free at 800-225-5478.

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

Total Returns for Class A Shares

Highest Quarterly Return:
Third Quarter 2009, 2.93%

Lowest Quarterly Return:
Second Quarter 2004, -1.76%

Class B total returns in the table below do not reflect the automatic conversion of Class B shares to Class A shares after eight years.

Average Annual Total Returns
(for the periods ended December 31, 2012)

Average Annual Total Returns Loomis Sayles Limited Term Government and Agency Fund	Past 1 Year	Past 5 Years	Past 10 Years
Class A	0.04%	4.00%	3.36%
Class A Return After Taxes on Distributions	(0.74%)	2.96%	2.15%
Class A Return After Taxes on Distributions & Sale of Fund Shares	0.03%	2.81%	2.15%
Class B	(2.61%)	3.53%	2.92%
Class C	1.39%	3.87%	2.92%
Class Y	3.41%	4.90%	3.94%
Barclays U.S. 1-5 Year Government Bond Index	0.97%	3.39%	3.38%

The Fund’s current adviser assumed that function on September 1, 2003. Prior to that, it served as subadviser to the Fund, a role it assumed in June 2001. The returns shown in the bar chart and table for periods prior to September 15, 2003 reflect the results of the CDC Nvest Limited Term U.S. Government Fund, whose assets and liabilities were reorganized into the Fund on September 12, 2003.

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

[1] Loomis, Sayles & Company, L.P. ("Loomis Sayles" or the "Adviser") has given a binding contractual undertaking to the Fund to limit the amount of the Fund's total annual fund operating expenses to 0.85%, 1.60%, 1.60% and 0.60% of the Fund's average daily net assets for Class A, B, C 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 January 31, 2014 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 0.85%, 1.60%, 1.60% and 0.60% of the Fund's average daily net assets for Class A, B, C, and Y shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.

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Loomis Sayles Small Cap Growth Fund

loomis sayles small cap growth fund

INVESTMENT OBJECTIVE

The Fund’s investment objective is long-term capital growth from investments in common stocks or other equity securities.

FUND FEES & EXPENSES

The following table describes the fees and expenses that you may pay if you buy and hold shares of the Fund.

The Fund does not impose a sales charge, a redemption fee or an exchange fee.

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

Annual Fund Operating Expenses Loomis Sayles Small Cap Growth Fund		Institutional Class	Retail Class	Class N
Management fees		0.75%	0.75%	0.75%
Distribution and/or service (12b-1) fees		none	0.25%	none
Other expenses		0.20%	0.28%	0.10%	[1]
Total annual fund operating expenses		0.95%	1.28%	0.85%
Fee waiver and/or expense reimbursement	[2]	none	0.03%	none
Total annual fund operating expenses after fee waiver and/or expense reimbursement		0.95%	1.25%	0.85%

Example

The 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. The example also assumes that your investment has a 5% return each year and the Fund’s operating expenses remain the same. The example for the Institutional Class shares and the Class N shares is based on Total Annual Fund Operating Expenses for all periods. The example for Retail Class shares is based on the Total Annual Fund Operating Expenses After Fee Waiver and/or Expense Reimbursement for the first year and on the Total Annual Fund Operating Expenses for the remaining years. Although your actual costs may be higher or lower, based on these assumptions your costs would be:

Expense Example Loomis Sayles Small Cap Growth Fund (USD $)	1 year	3 years	5 years	10 years
Institutional Class	97	303	525	1,166
Retail Class	127	403	699	1,543
Class N	87	271	471	1,049

Portfolio Turnover

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes for you if your Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During its most recently ended fiscal year, the Fund’s portfolio turnover rate was 77% of the average value of its portfolio.

INVESTMENTS, RISKS AND PERFORMANCE

Principal Investment Strategies

The Fund normally will invest at least 80% of its net assets (plus any borrowings made for investment purposes) in the equity securities of “small-cap companies,” including preferred stocks, warrants, securities convertible into common or preferred stocks and other equity-like interests in an entity. Currently, the Fund defines a small-cap company to be one whose market capitalization either falls within the capitalization range of the Russell 2000 Index, an index that tracks stocks of 2,000 of the smallest U.S. companies, or is $3 billion or less at the time of investment. The Fund may invest the rest of its assets in companies of any size, including large-capitalization companies.

In deciding which securities to buy and sell, Loomis Sayles typically seeks to identify companies that it believes have distinctive products, technologies, or services; dynamic earnings growth; prospects for high levels of profitability; and solid management. Loomis Sayles typically does not consider current income when making buy/sell decisions.

The Fund may invest any portion of its assets in securities of Canadian issuers and up to 20% of its assets in other foreign securities, including emerging markets securities. The Fund may also invest in securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”).

The Fund may engage, for hedging and investment purposes, in foreign currency transactions, options and futures transactions.

Principal Risks

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

Credit Risk is the risk that the issuer or guarantor of a fixed-income security in which the Fund invests, or the counterparty to a derivatives or other transaction will fail financially or otherwise be unwilling or unable to meet their obligations to the Fund.

Currency Risk is the risk that the value of the Fund’s investments will fall as a result of changes in exchange rates. Loomis Sayles may elect not to hedge currency risk or may hedge imperfectly, which may cause the Fund to incur losses that would not have been incurred had the risk been hedged.
Derivatives Risk is the risk that the value of the Fund’s derivative investments such as forward currency contracts, options and futures transactions will fall, for example, because of changes in the value of the underlying reference instruments, pricing difficulties or lack of correlation with the underlying investments. The use of derivatives for other than hedging purposes may be considered a speculative activity, and involves greater risks than are involved in hedging. There is also the risk that the Fund may be unable to terminate or sell a derivatives position at an advantageous time or price. Moreover, a number of broker-dealers and other financial institutions have recently experienced extreme financial difficulty, sometimes resulting in bankruptcy of the institution. There can be no assurance that the Fund’s derivative counterparties will not experience similar financial difficulties, possibly resulting in losses to the Fund. This risk is greater for forward currency contracts and other over-the-counter traded derivatives. Investing in derivatives gives rise to other risks, such as leverage risk, liquidity risk, credit risk, counterparty risk, interest rate risk and market risk. The use of derivatives may cause the Fund to incur losses greater than those which would have occurred had derivatives not been used.

Emerging Markets Risk is the risk that the Fund’s investments may face greater foreign securities risk. Investing in companies traded in emerging securities markets, which may be smaller and have shorter operating histories than companies in developed markets, involves risks in addition to, and greater than, those generally associated with investing in developed foreign markets. The extent of economic development, political stability, market depth, infrastructure, capitalization and regulatory oversight in emerging market economies is generally less than in more developed markets.

Equity Securities Risk is the risk that the value of a stock may decline for a number of reasons that relate directly to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services, or the equity markets generally. 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 Loomis Sayles’ assessment of the prospects for a company’s growth is wrong, or if Loomis Sayles’ 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 Loomis Sayles has placed on it. In the event an issuer is liquidated or declares bankruptcy, the claims of owners of the issuer’s bonds generally take precedence over the claims of those who own preferred stock or common stock.

Foreign Securities Risk is the risk that the value of the Fund’s foreign investments will fall as a result of foreign political, social, economic, environmental, credit, informational or currency changes or other issues relating to foreign investing generally. Foreign securities may be subject to higher volatility than U.S. securities, varying degrees of regulation and limited liquidity. The Fund’s investments in foreign securities may be subject to foreign withholding taxes, which would decrease the yield on those securities.

Issuer Risk is the risk that the value of securities may decline due to a number of reasons relating to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods and services.

Leverage Risk is the risk associated with securities or practices (e.g., borrowing and the use of certain derivatives) and investment in certain types of derivatives that multiply small index, market or asset price movements into larger changes in value. Use of derivative instruments may involve leverage. When a derivative is used as a hedge against an offsetting position that the Fund also holds, any loss generated by the derivative should be substantially offset by gains on the hedged instrument, and vice versa. To the extent that the Fund uses a derivative for purposes other than as a hedge, or if the Fund hedges imperfectly, the Fund is directly exposed to the risks of that derivative and any loss generated by the derivative will not be offset by a gain. Futures and forward currency contracts are derivatives and may be subject to this type of risk.
Liquidity Risk is the risk that the Fund may be unable to find a buyer for its investments when it seeks to sell them or to receive the price it expects. Securities acquired in a private placement, such as Rule 144A securities, generally are subject to strict restrictions on resale and there may be no liquid secondary market or ready purchaser for such securities. Therefore, the Fund may be unable to dispose of such securities when it desires to do so, or at the most advantageous time or price. Liquidity issues may also make it difficult to value the Fund’s investments.

Management Risk is the risk that Loomis Sayles’ investment techniques will be unsuccessful and cause the Fund to incur losses.

Market Risk is the risk that the market value of a security will move up and down, sometimes rapidly and unpredictably, based upon a change in an issuer’s financial condition, as well as overall market and economic conditions.

Small-Capitalization Companies Risk is the risk that the Fund’s investments may be subject to more abrupt price movements, limited markets, increased volatility and less liquidity than investments in larger, more established companies, which could adversely affect the value of the portfolio.

Risk/Return Bar Chart and Table

The following bar chart and table give an indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s average annual returns for the one-year, five-year, ten-year and life-of-fund periods compare to those of a broad measure of market performance. The Fund’s past performance (before and after taxes) does not necessarily indicate how the Fund will perform in the future. Updated performance information is available online at www.loomissayles.com and/or by calling the Fund toll-free at 800-633-3330.

Total Returns for Institutional Class Shares

The Fund’s best quarter was 25.29%, (second quarter of 2003), and the Fund’s worst quarter was -26.86%, (fourth quarter of 2008).

Average Annual Total Returns for the periods ended December 31, 2012

Because the Fund did not have Class N shares outstanding during the periods shown, performance is that of the Institutional Class shares of the Fund. Class N shares would have had substantially similar returns because they would have been invested in the same portfolio of securities as Institutional Class shares and would only differ to the extent the classes did not have the same expenses. The Class N returns may be higher than the returns of Institutional Class shares because Institutional Class shares are subject to higher expenses.

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-deferred 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 the Institutional Class of the Fund. After-tax returns for other classes of the Fund will vary. Index performance reflects no deduction for fees, expenses or taxes.

Average Annual Total Returns Loomis Sayles Small Cap Growth Fund	One Year	Five Years	Ten Years	Life of Fund	Inception Date
Institutional Class	10.29%	3.50%	11.34%	4.80%	Dec. 31, 1996
Institutional Class Return After Taxes on Distributions	10.29%	3.50%	11.34%	4.58%	Dec. 31, 1996
Institutional Class Return After Taxes on Distributions and Sale of Fund Shares	6.69%	3.00%	10.19%	4.12%	Dec. 31, 1996
Retail Class	9.96%	3.22%	11.04%	4.53%	Dec. 31, 1996
Class N	10.29%	3.50%	11.34%	4.80%	Dec. 31, 1996
Russell 2000 Growth Index	14.59%	3.49%	9.80%	4.58%	Dec. 31, 1996

[1] Other expenses for Class N shares are based on estimated amounts 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 1.00%, 1.25% and 0.95% of the Fund's average daily net assets for Institutional Class shares, Retail Class shares and Class N 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 January 31, 2014 and may be terminated before then only with the consent of the Fund's Board of Trustees. The Adviser will be permitted to recover, on a class by class basis, management fees waived and/or expenses reimbursed to the extent that expenses in later periods fall below 1.00%, 1.25% and 0.95% of the Fund's average daily net assets for Institutional Class shares, Retail Class shares and Class N shares, respectively. The Fund will not be obligated to repay any such waived/reimbursed fees and expenses more than one year after the end of the fiscal year in which the fees or expenses were waived/reimbursed.