S000041917 [Member] Investment Risks - AMG Boston Common Global Impact Fund |
Sep. 30, 2025 |
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| Foreign Investment Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Foreign Investment Risk—investments in foreign issuers involve additional risks (such as risks arising from less frequent trading, changes in political or social conditions, and less publicly available information about non-U.S. issuers) that differ from those associated with investments in U.S. issuers and may result in greater price volatility.
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| Emerging Markets Risk [Member] | |
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| Risk [Text Block] | Emerging Markets Risk—investments in emerging markets are subject to the general risks of foreign investments, as well as additional risks which can result in greater price volatility. Such additional risks include the risk that markets in emerging market countries are typically less developed and less liquid than markets in developed countries and such markets are subjected to increased economic, political, or regulatory uncertainties.
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| Currency Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Currency Risk—fluctuations in exchange rates may affect the total loss or gain on a non-U.S. dollar investment when converted back to U.S. dollars and exposure to non-U.S. currencies may subject the Fund to the risk that those currencies will decline in value relative to the U.S. dollar.
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| ESG Investing Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | ESG Investing Risk—because applying the Fund’s ESG investment criteria may result in the selection or exclusion of securities of certain issuers for reasons other than financial performance, the Fund’s investment returns may underperform funds that do not incorporate ESG factors into their investment process. The incorporation of ESG criteria into the investment process may affect the Fund’s investment exposure to certain companies, sectors, regions, countries or types of investments, which could negatively impact the Fund’s performance depending on whether such investments are in or out of favor. Applying ESG criteria to investment decisions is qualitative and subjective by nature, and there is no guarantee that the criteria utilized by the Subadviser or any judgment exercised by the Subadviser will improve the financial performance of the Fund or reflect the beliefs or values of any particular investor. ESG standards differ by region and industry, and a company’s ESG practices or the Subadviser’s assessment of a company’s ESG practices may change over time. The Subadviser’s evaluation of a company also may be dependent on the availability of timely, complete and accurate ESG data reported by issuers and/or third party data providers. Different methodologies may be used by the various issuers and third party sources that provide ESG data, and such ESG data often lacks standardization, consistency and transparency.
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| Growth Stock Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Growth Stock Risk—the prices of equity securities of companies that are expected to experience relatively rapid earnings growth, or “growth stocks,” may be more sensitive to market movements because the prices tend to reflect future investor expectations rather than just current profits.
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| Large Capitalization Stock Risk [Member] | |
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| Risk [Text Block] | Large-Capitalization Stock Risk—the stocks of large-capitalization companies are generally more mature and may not be able to reach the same levels of growth as the stocks of small- or mid-capitalization companies.
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| Liquidity Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Liquidity Risk—the Fund may not be able to dispose of particular investments, such as illiquid securities, readily at favorable times or prices or the Fund may have to sell them at a loss.
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| Management Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Management Risk—because the Fund is an actively managed investment portfolio, security selection or focus on securities in a particular style, market sector or group of companies may cause the Fund to incur losses or underperform relative to its benchmarks or other funds with a similar investment objective. There can be no guarantee that the Subadviser’s investment techniques and risk analysis will produce the desired result.
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| Mid Capitalization Stock Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Mid-Capitalization Stock Risk—Although the Fund may invest in securities in any capitalization range, securities of mid-capitalization companies may pose additional risks. The stocks of mid-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.
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| Political Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Political Risk—changes in the general political and social environment of a country can have substantial effects on the value of investments exposed to that country.
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| Sector Risk [Member] | |
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| Risk [Text Block] | Sector Risk—issuers and companies that are in similar industry sectors may be similarly affected by particular economic or market events; to the extent the Fund has substantial holdings within a particular sector, the risks associated with that sector increase. Stocks in the information technology sector may comprise a significant portion of the Fund’s portfolio. The information technology sector may be affected by technological obsolescence, short product cycles, falling prices and profits, competitive pressures and general market conditions.
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| Small Capitalization Stock Risk [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Small-Capitalization Stock Risk—although the Fund may invest in securities in any capitalization range, securities of small-capitalization companies may pose additional risks. The stocks of small-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.
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| Value Stock Risk [Member] | |
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| Risk [Text Block] | Value Stock Risk—value stocks may perform differently from the market as a whole and may be undervalued by the market for a long period of time.
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| Market Risks [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Market Risk—market prices of investments held by the Fund may fall rapidly or unpredictably due to a variety of factors, including economic or market conditions, or other factors including terrorism, war, natural disasters and the spread of infectious illness or other public health issues, including epidemics or pandemics, or in response to events that affect particular industries or companies. In addition, unexpected political, regulatory, trade and diplomatic events within the United States and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy, perhaps suddenly and to a significant degree.
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| Risk Lose Money [Member] | |
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| Risk [Text Block] | There is the risk that you may lose money on your investment. |
| Risk Not Insured Depository Institution [Member] | |
| Prospectus [Line Items] | |
| Risk [Text Block] | Aninvestment in the Fund is not a deposit or obligation of any bank,is not endorsed or guaranteed by any bank, and is not insured bythe Federal Deposit Insurance Corporation (“FDIC”) or any othergovernment agency. |