S000016733 [Member] Annual Total Returns |
12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
Dec. 31, 2019 |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|
| AMG River Road Small-Mid Cap Value Fund | CLASS N SHARES | ||||||||||
| Prospectus [Line Items] | ||||||||||
| Annual Return [Percent] | 4.01% | 12.46% | 14.40% | (8.53%) | 23.33% | 1.71% | 32.38% | (6.44%) | 15.35% | 27.13% |