Class I [Member] Investment Risks - Class I - AMG Yacktman Fund	Dec. 31, 2025
Large Capitalization Stock Risk [Member]
Prospectus [Line Items]
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.
Value Stock Risk [Member]
Prospectus [Line Items]
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.
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.
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. To the extent the Fund invests a substantial portion of its assets in a relatively small number of securities, the Fund’s net asset value may be more volatile and the Fund may involve more risk than a fund that invests in a greater number of securities. There can be no guarantee that the Subadviser’s investment techniques and risk analysis will produce the desired result.
Convertible Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Convertible Securities Risk— convertible preferred stocks, which are convertible into shares of the issuer’s common stock and pay regular dividends, and convertible debt securities, which are convertible into shares of the issuer’s common stock and bear interest, are subject to the risks of equity securities and fixed income securities. The lower the conversion premium, the more likely the price of the convertible security will follow the price of the underlying common stock. Conversely, higher premium convertible securities are more likely to exhibit the behavior of bonds because the likelihood of conversion is lower, which may cause their prices to fall as interest rates rise. There is the risk that the issuer of convertible preferred stock will not be able to make dividend payments or that the issuer of a convertible bond will not be able to make principal and/or interest payments.
Credit and Counterparty Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Credit and Counterparty Risk—the issuer of bonds or other debt securities or a counterparty to a derivatives contract (including over-the-counter counterparties as well as brokers and clearinghouses in respect of exchange-traded and/or cleared products) may be unable or unwilling, or may be perceived as unable or unwilling, to make timely interest, principal or settlement payments or otherwise honor its obligations. Changes in an issuer’s financial strength, credit rating or the market’s perception of an issuer's creditworthiness may also affect the value of the Fund’s investment in that issuer.
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.
Debt Securities Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Debt Securities Risk—the value of a debt security changes in response to various factors, including, for example, market-related factors, such as changes in interest rates or changes in the actual or perceived ability of an issuer to meet its obligations. Investments in debt securities are subject to, among other risks, credit risk, interest rate risk, extension risk, prepayment risk and liquidity risk.
Emerging Markets Risk [Member]
Prospectus [Line Items]
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.
Geographic Focus Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Geographic Focus Risk—to the extent the Fund focuses its investments in a particular country, group of countries or geographic region, the Fund is particularly susceptible to economic, political, regulatory or other events or conditions affecting such countries or region, and the Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund and may result in losses. South Korea. Investments in South Korean issuers will subject the Fund to legal, regulatory, political, currency, security, and economic risks that are specific to South Korea. In addition, economic and political developments of South Korea’s neighbors, including escalated tensions involving North Korea and any outbreak of hostilities involving North Korea, or the threat of an outbreak of such hostilities, may have a severe adverse effect on the South Korean economy. The South Korean economy is reliant on trading exports, and disruptions or decreases in trade activity could lead to declines in South Korea’s economic growth potential.
High Yield Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	High Yield Risk—below investment grade debt securities and unrated securities of similar credit quality (commonly known as “junk bonds” or “high yield securities”) may be subject to greater levels of interest rate, credit, liquidity, and market risk than higher-rated securities. These securities are considered predominately speculative with respect to the issuer’s continuing ability to make principal and interest payments.
Interest Rate Risks [Member]
Prospectus [Line Items]
Risk [Text Block]	Interest Rate Risk—fixed coupon payments (cash flows) of bonds and debt securities may become less competitive with the market in periods of rising interest rates and cause bond prices to decline. During periods of increasing interest rates, the Fund may experience high levels of volatility and shareholder redemptions, and may have to sell securities at times when it would otherwise not do so, and at unfavorable prices, which could reduce the returns of the Fund.
Sector Risk [Member]
Prospectus [Line Items]
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.
Small and Mid Capitalization Stock Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Small- and Mid-Capitalization Stock Risk—the stocks of small- and mid-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.
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.
Risk Lose Money [Member]
Prospectus [Line Items]
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]	An investment in the Fund is not a deposit or obligation of any bank, is not endorsed or guaranteed by any bank, and is not insured by the Federal Deposit Insurance Corporation (“FDIC”) or any other government agency.

Class I [Member] Investment Risks - Class I - AMG Yacktman Fund

Dec. 31, 2025

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.

Prospectus [Line Items]

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.

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.

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. To the extent the Fund invests a substantial portion of its assets in a relatively small number of securities, the Fund’s net asset value may be more volatile and the Fund may involve more risk than a fund that invests in a greater number of securities. There can be no guarantee that the Subadviser’s investment techniques and risk analysis will produce the desired result.

Convertible Securities Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Convertible Securities Risk— convertible preferred stocks, which are convertible into shares of the issuer’s common stock and pay regular dividends, and convertible debt securities, which are convertible into shares of the issuer’s common stock and bear interest, are subject to the risks of equity securities and fixed income securities. The lower the conversion premium, the more likely the price of the convertible security will follow the price of the underlying common stock. Conversely, higher premium convertible securities are more likely to exhibit the behavior of bonds because the likelihood of conversion is lower, which may cause their prices to fall as interest rates rise. There is the risk that the issuer of convertible preferred stock will not be able to make dividend payments or that the issuer of a convertible bond will not be able to make principal and/or interest payments.

Credit and Counterparty Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Credit and Counterparty Risk—the issuer of bonds or other debt securities or a counterparty to a derivatives contract (including over-the-counter counterparties as well as brokers and

clearinghouses in respect of exchange-traded and/or cleared products) may be unable or unwilling, or may be perceived as unable or unwilling, to make timely interest, principal or settlement payments or otherwise honor its obligations. Changes in an issuer’s financial strength, credit rating or the market’s perception of an issuer's creditworthiness may also affect the value of the Fund’s investment in that issuer.

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.

Debt Securities Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Debt Securities Risk—the value of a debt security changes in response to various factors, including, for example, market-related factors, such as changes in interest rates or changes in the actual or perceived ability of an issuer to meet its obligations. Investments in debt securities are subject to, among other risks, credit risk, interest rate risk, extension risk, prepayment risk and liquidity risk.

Emerging Markets Risk [Member]

Prospectus [Line Items]

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.

Geographic Focus Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Geographic Focus Risk—to the extent the Fund focuses its investments in a particular country, group of countries or geographic region, the Fund is particularly susceptible to economic, political, regulatory or other events or conditions affecting such countries or region, and the Fund’s NAV may be more volatile than the NAV of a more geographically diversified fund and may result in losses.

South Korea. Investments in South Korean issuers will subject the Fund to legal, regulatory, political, currency, security, and economic risks that are specific to South Korea. In addition, economic and political developments of South Korea’s neighbors, including escalated tensions involving North Korea and any outbreak of hostilities involving North Korea, or the threat of an outbreak of such hostilities, may have a severe adverse effect on the South Korean economy. The South Korean economy is reliant on trading exports, and disruptions or decreases in trade activity could lead to declines in South Korea’s economic growth potential.

High Yield Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

High Yield Risk—below investment grade debt securities and unrated securities of similar credit quality (commonly known as “junk bonds” or “high yield securities”) may be subject to greater levels of interest rate, credit, liquidity, and market risk than higher-rated securities. These securities are considered predominately speculative with respect to the issuer’s continuing ability to make principal and interest payments.

Interest Rate Risks [Member]

Prospectus [Line Items]

Risk [Text Block]

Interest Rate Risk—fixed coupon payments (cash flows) of bonds and debt securities may become less competitive with the market in periods of rising interest rates and cause bond prices to decline. During periods of increasing interest rates, the Fund

may experience high levels of volatility and shareholder redemptions, and may have to sell securities at times when it would otherwise not do so, and at unfavorable prices, which could reduce the returns of the Fund.

Sector Risk [Member]

Prospectus [Line Items]

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.

Small and Mid Capitalization Stock Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Small- and Mid-Capitalization Stock Risk—the stocks of small- and mid-capitalization companies often have greater price volatility, lower trading volume, and less liquidity than the stocks of larger, more established companies.

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.

Risk Lose Money [Member]

Prospectus [Line Items]

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]

An investment in the Fund is not a deposit or obligation of any bank, is not endorsed or guaranteed by any bank, and is not insured by the Federal Deposit Insurance Corporation (“FDIC”) or any other government agency.