Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Supplement to Prospectus [Text Block]	rr_SupplementToProspectusTextBlock	Supplement dated February 22, 2023, to the Prospectus and Summary Prospectus of the Loomis Sayles Growth Fund (the “Fund”), each dated February 1, 2023, as may be revised or supplemented from time to time. Effective immediately, the fourth paragraph within the sub‑section “Principal Investment Strategies” within the “Fund Summary” and the “More About Goals and Strategies” section of the Fund’s prospectus is hereby amended and restated with regard to the Fund: The Fund may also invest up to 20% of its assets in foreign securities, including depositary receipts and emerging market securities. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in the U.S. equity indices published by S&P Global Ratings or Russell Investments or if the security’s country of risk defined by Bloomberg is the United States. The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in interests in real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”). Except as provided above or as required by applicable law, the Fund is not limited in the percentage of its assets that it may invest in these instruments. Effective immediately, the following paragraph is added to the “Principal Investment Risks” sub‑section within the “Fund Summary” with regard to the Fund: 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.
Loomis Sayles Growth Fund
Risk/Return:	rr_RiskReturnAbstract
Supplement to Prospectus [Text Block]	rr_SupplementToProspectusTextBlock	Supplement dated February 22, 2023, to the Prospectus and Summary Prospectus of the Loomis Sayles Growth Fund (the “Fund”), each dated February 1, 2023, as may be revised or supplemented from time to time. Effective immediately, the fourth paragraph within the sub‑section “Principal Investment Strategies” within the “Fund Summary” and the “More About Goals and Strategies” section of the Fund’s prospectus is hereby amended and restated with regard to the Fund: The Fund may also invest up to 20% of its assets in foreign securities, including depositary receipts and emerging market securities. Although certain equity securities purchased by the Fund may be issued by domestic companies incorporated outside of the United States, the Adviser does not consider these securities to be foreign if they are included in the U.S. equity indices published by S&P Global Ratings or Russell Investments or if the security’s country of risk defined by Bloomberg is the United States. The Fund may also engage in foreign currency transactions (including foreign currency forwards and foreign currency futures) for hedging purposes, invest in options for hedging and investment purposes and invest in interests in real estate investment trusts (“REITs”) and securities issued pursuant to Rule 144A under the Securities Act of 1933 (“Rule 144A securities”). Except as provided above or as required by applicable law, the Fund is not limited in the percentage of its assets that it may invest in these instruments. Effective immediately, the following paragraph is added to the “Principal Investment Risks” sub‑section within the “Fund Summary” with regard to the Fund: 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.