v3.26.1
S000009877 [Member] Expense Example - AMG TimesSquare Small Cap Growth Fund
Dec. 31, 2025
USD ($)
Class Z  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year $ 99
Expense Example, with Redemption, 3 Years 330
Expense Example, with Redemption, 5 Years 580
Expense Example, with Redemption, 10 Years 1,297
Class N  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 119
Expense Example, with Redemption, 3 Years 393
Expense Example, with Redemption, 5 Years 687
Expense Example, with Redemption, 10 Years 1,525
Class I  
Prospectus [Line Items]  
Expense Example, with Redemption, 1 Year 105
Expense Example, with Redemption, 3 Years 349
Expense Example, with Redemption, 5 Years 613
Expense Example, with Redemption, 10 Years $ 1,366