Mirova Global Megatrends Fund Mirova Global Megatrends Fund Vaughan Nelson Small Cap Fund Vaughan Nelson Small Cap Fund Natixis Oakmark International Fund Natixis Oakmark International Fund Natixis U.S. Equity Opportunities Fund Natixis U.S. Equity Opportunities Fund Dmultiaffiliatestatutoryprospectus_4824 Natixis Funds Trust I Dloomisharrisstatutoryprospectus_4833 Natixis Funds Trust I Dmultiaffiliatefundssai_4823 5-1 Multi-Affiliate Funds_SAI Dloomisharrisfundssai_4822 5-1 Loomis Harris Funds_SAI Class A - C000167845 Class A Class C - C000167846 Class C Class N - C000190736 Class N Class T - C000188563 Class T Class Y - C000167847 Class Y Class A - C000018172 Class A Class B - C000018173 B Class C - C000018174 Class C Class N - C000190733 Class N Class T - C000188561 Class T Class Y - C000069268 Class Y Class A - C000094872 Class A Class C - C000094873 Class C Class N - C000190734 Class N Class T - C000188562 Class T Class Y - C000190735 Class Y Class A - C000018161 Class A Class B - C000018162 B Class C - C000018163 Class C Class N - C000190732 Class N Class T - C000188559 Class T Class Y - C000018164 Class Y S&P 500® Index S&P 500® Index ESG Investing Risk ESG Investing Risk [Member] Currency Risk Currency Risk [Member] MSCI World Index (Net) MSCI World Index (Net) Small- and Mid-Capitalization Companies Risk Small- and Mid-Capitalization Companies Risk [Member] Equity Securities Risk Equity Securities Risk [Member] Small-Capitalization Companies Risk Small-Capitalization Companies Risk [Member] Market/Issuer Risk Market/Issuer Risk [Member] Management Risk Management Risk [Member] Liquidity Risk Liquidity Risk [Member] Convertible Securities Risk Convertible Securities Risk [Member] Cybersecurity and Technology Risk Cybersecurity and Technology Risk [Member] Emerging Markets Risk Emerging Markets Risk [Member] Foreign Securities Risk Foreign Securities Risk [Member] Large Shareholder Transaction Risk Large Shareholder Transaction Risk [Member] REITs Risk REITs Risk [Member] Russell 3000® Index Russell 3000® Index Russell 2000 Value Index Russell 2000 Value Index Focused Investment Risk Focused Investment Risk [Member] Value Style Risk Value Style Risk [Member] MSCI World ex USA Index (Net) MSCI World ex USA Index (Net) Allocation Risk Allocation Risk [Member] Credit/Counterparty Risk Credit/Counterparty Risk [Member] Russell 1000® Index Russell 1000® Index