S000020207 [Member] Annual Fund Operating Expenses - AMG GW&K Small Cap Value Fund |
Dec. 31, 2025 |
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|---|---|---|---|---|---|---|
| Prospectus [Line Items] | ||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | May 1, 2027 | |||||
| Class N | ||||||
| Prospectus [Line Items] | ||||||
| Management Fees (as a percentage of Assets) | 0.70% | |||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||
| Other Expenses (as a percentage of Assets): | 0.50% | [1] | ||||
| Expenses (as a percentage of Assets) | 1.20% | |||||
| Fee Waiver or Reimbursement | (0.05%) | [2] | ||||
| Net Expenses (as a percentage of Assets) | 1.15% | [2] | ||||
| Class I | ||||||
| Prospectus [Line Items] | ||||||
| Management Fees (as a percentage of Assets) | 0.70% | |||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||
| Other Expenses (as a percentage of Assets): | 0.30% | [1] | ||||
| Expenses (as a percentage of Assets) | 1.00% | |||||
| Fee Waiver or Reimbursement | (0.05%) | [2] | ||||
| Net Expenses (as a percentage of Assets) | 0.95% | [2] | ||||
| Class Z | ||||||
| Prospectus [Line Items] | ||||||
| Management Fees (as a percentage of Assets) | 0.70% | |||||
| Distribution and Service (12b-1) Fees | 0.00% | |||||
| Other Expenses (as a percentage of Assets): | 0.25% | [1] | ||||
| Expenses (as a percentage of Assets) | 0.95% | |||||
| Fee Waiver or Reimbursement | (0.05%) | [2] | ||||
| Net Expenses (as a percentage of Assets) | 0.90% | [2] | ||||
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