2.2.0.25truefalse000601 - Document - Risk/Return Summary {Unlabeled} - (Loomis Sayles Core Plus Bond Fund)falsefalsefalse1falsefalsetruefalse{dei_DocumentInformationDocumentAxis} : Class B And C Member 2/1/2011 - 2/1/2011 Duration_2_1_2011_To_2_1_2011_dei_DocumentInformationDocumentAxis_cik000770540_ClassBAndCMemberhttp://www.sec.gov/CIK0000770540duration2011-02-01T00:00:002011-02-01T00:00:00falsefalseClass A, B and Cdei_DocumentInformationDocumentAxisxbrldihttp://xbrl.org/2006/xbrldicik000770540_ClassBAndCMemberdei_DocumentInformationDocumentAxisexplicitMember3false0cik000770540_SupplementTextBlockcik000770540falsenadurationSupplement [Text Block]falsefalsefalsefalsefalsefalsefalsefalsefalsefalselabel1falsefalsefalse00<div> NATIXIS FUNDS Supplement dated May 2, 2011 to the Class A, B and C Prospectus, as applicable, each dated February 1, 2011, as may be revised or supplemented from time to time, for the following funds:   <table border="0" cellspacing="0" cellpadding="0" width="100%" align="center"> <tr><td width="50%"> </td> <td valign="bottom" width="2%"> </td> <td width="48%"> </td></tr> <tr><td valign="top"> Loomis Sayles Core Plus Bond Fund Loomis Sayles High Income Fund</td> <td valign="bottom"> </td> <td valign="bottom"> Loomis Sayles Limited Term Government and Agency Fund</td></tr> <tr><td valign="top">Loomis Sayles International Bond Fund</td> <td valign="bottom"> </td> <td valign="bottom">Loomis Sayles Strategic Income Fund</td></tr> <tr><td valign="top">Loomis Sayles Investment Grade Bond Fund</td> <td valign="bottom"> </td> <td valign="bottom"> </td></tr></table> Effective immediately, the following paragraph under the section "Fund Fees & Expenses" within each Fund Summary is amended and restated as follows: 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 53 of the Prospectus and on page 106 in the section "Reduced Sales Charges" of the Statement of Additional Information ("SAI"). Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles Core Plus Bond Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 1.71%. Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles High Income Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 4.94%. Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles International Bond Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 2.70%. Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles Investment Grade Bond Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 2.15%. Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles Limited Term Government and Agency Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 0.44%. Effective immediately, the following sentence is added under the bar chart in the section "Risk/Return Bar Chart and Table" within the section "Investments, Risks and Performance" with regard to Loomis Sayles Strategic Income Fund: The Fund's Class A shares total return year to date as of March 31, 2011 was 3.63%. </div>falsefalsefalsefalsefalseOtherus-types:textBlockItemTypestringSupplement [Text Block]No authoritative reference available.falsefalseSupplement [Text Block]11Risk/Return Summary - (Loomis Sayles Core Plus Bond Fund) (Class A, B and C)UnKnownUnKnownUnKnownUnKnownfalsetrue