v3.26.1
Expense Example - Natixis Funds Trust I
Dec. 31, 2025
USD ($)
Mirova Global Megatrends Fund | Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 690
Expense Example, with Redemption, 3 Years 946
Expense Example, with Redemption, 5 Years 1,221
Expense Example, with Redemption, 10 Years 2,005
Mirova Global Megatrends Fund | Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 298
Expense Example, with Redemption, 3 Years 625
Expense Example, with Redemption, 5 Years 1,077
Expense Example, with Redemption, 10 Years 2,140
Mirova Global Megatrends Fund | Class N  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 91
Expense Example, with Redemption, 3 Years 286
Expense Example, with Redemption, 5 Years 497
Expense Example, with Redemption, 10 Years 1,107
Mirova Global Megatrends Fund | Class Y  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 97
Expense Example, with Redemption, 3 Years 316
Expense Example, with Redemption, 5 Years 552
Expense Example, with Redemption, 10 Years 1,231
Vaughan Nelson Small Cap Fund | Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 696
Expense Example, with Redemption, 3 Years 964
Expense Example, with Redemption, 5 Years 1,251
Expense Example, with Redemption, 10 Years 2,069
Vaughan Nelson Small Cap Fund | Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 304
Expense Example, with Redemption, 3 Years 643
Expense Example, with Redemption, 5 Years 1,108
Expense Example, with Redemption, 10 Years 2,203
Vaughan Nelson Small Cap Fund | Class N  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 97
Expense Example, with Redemption, 3 Years 303
Expense Example, with Redemption, 5 Years 525
Expense Example, with Redemption, 10 Years 1,166
Vaughan Nelson Small Cap Fund | Class Y  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 103
Expense Example, with Redemption, 3 Years 334
Expense Example, with Redemption, 5 Years 584
Expense Example, with Redemption, 10 Years 1,300
Natixis Oakmark International Fund | Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 685
Expense Example, with Redemption, 3 Years 973
Expense Example, with Redemption, 5 Years 1,282
Expense Example, with Redemption, 10 Years 2,157
Natixis Oakmark International Fund | Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 293
Expense Example, with Redemption, 3 Years 653
Expense Example, with Redemption, 5 Years 1,140
Expense Example, with Redemption, 10 Years 2,291
Natixis Oakmark International Fund | Class N  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 87
Expense Example, with Redemption, 3 Years 361
Expense Example, with Redemption, 5 Years 657
Expense Example, with Redemption, 10 Years 1,497
Natixis Oakmark International Fund | Class Y  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 92
Expense Example, with Redemption, 3 Years 345
Expense Example, with Redemption, 5 Years 618
Expense Example, with Redemption, 10 Years 1,396
Natixis U.S. Equity Opportunities Fund | Class A  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 677
Expense Example, with Redemption, 3 Years 893
Expense Example, with Redemption, 5 Years 1,126
Expense Example, with Redemption, 10 Years 1,795
Natixis U.S. Equity Opportunities Fund | Class C  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 284
Expense Example, with Redemption, 3 Years 569
Expense Example, with Redemption, 5 Years 980
Expense Example, with Redemption, 10 Years 1,930
Natixis U.S. Equity Opportunities Fund | Class N  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 77
Expense Example, with Redemption, 3 Years 248
Expense Example, with Redemption, 5 Years 435
Expense Example, with Redemption, 10 Years 974
Natixis U.S. Equity Opportunities Fund | Class Y  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 83
Expense Example, with Redemption, 3 Years 259
Expense Example, with Redemption, 5 Years 450
Expense Example, with Redemption, 10 Years $ 1,002