v3.26.1
Expense Example, No Redemption - Natixis Funds Trust I - Class C
Dec. 31, 2025
USD ($)
Mirova Global Megatrends Fund  
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year $ 198
Expense Example, No Redemption, 3 Years 625
Expense Example, No Redemption, 5 Years 1,077
Expense Example, No Redemption, 10 Years 2,140
Vaughan Nelson Small Cap Fund  
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year 204
Expense Example, No Redemption, 3 Years 643
Expense Example, No Redemption, 5 Years 1,108
Expense Example, No Redemption, 10 Years 2,203
Natixis Oakmark International Fund  
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year 193
Expense Example, No Redemption, 3 Years 653
Expense Example, No Redemption, 5 Years 1,140
Expense Example, No Redemption, 10 Years 2,291
Natixis U.S. Equity Opportunities Fund  
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year 184
Expense Example, No Redemption, 3 Years 569
Expense Example, No Redemption, 5 Years 980
Expense Example, No Redemption, 10 Years $ 1,930