S000016733 [Member] Annual Fund Operating Expenses - AMG River Road Small-Mid Cap Value Fund |
Oct. 31, 2025 |
|---|---|
| CLASS N SHARES | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.75% |
| Distribution and Service (12b-1) Fees | 0.25% |
| Other Expenses (as a percentage of Assets): | 0.28% |
| Expenses (as a percentage of Assets) | 1.28% |
| CLASS I SHARES | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.75% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.27% |
| Expenses (as a percentage of Assets) | 1.02% |
| CLASS Z Shares | |
| Prospectus [Line Items] | |
| Management Fees (as a percentage of Assets) | 0.75% |
| Distribution and Service (12b-1) Fees | 0.00% |
| Other Expenses (as a percentage of Assets): | 0.22% |
| Expenses (as a percentage of Assets) | 0.97% |