S000009865 [Member] Investment Risks - AMG Veritas Asia Pacific Fund	Dec. 31, 2025
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.
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.
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.
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.
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.
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.
Focused Investment Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Focused Investment Risk—to the extent the Fund invests a substantial portion of its assets in a relatively small number of securities or a particular market, industry, group of industries, country, region, group of countries, asset class or sector, it generally will be subject to greater risk than a fund that invests in a more diverse investment portfolio. In addition, the value of the Fund would be more susceptible to any single economic, market, political or regulatory occurrence affecting, for example, that particular market, industry, region or sector.
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. Greater China. The Fund is particularly susceptible to risks in the Greater China region, which consists of Hong Kong, The People’s Republic of China and Taiwan, among other countries. Economies in the Greater China region are dependent on the economies of other countries and can be significantly affected by currency fluctuations and increasing competition from other emerging economies in Asia with lower costs. Adverse events in any one country within the region may impact the other countries in the region or Asia as a whole. Markets in the Greater China region can experience significant volatility due to social, economic, regulatory and political uncertainties. Significant portions of the Chinese securities markets may become rapidly illiquid, as Chinese issuers have the ability to suspend the trading of their equity securities, and have shown a willingness to exercise that option in response to market volatility and other events. U.S. or foreign government sanctions or other investment restrictions or intervention could negatively affect the implementation of the Fund’s investment strategies, for example by precluding the Fund from making certain investments or causing the Fund to sell investments at disadvantageous times. China has yet to develop comprehensive securities, corporate, or commercial laws, its market is relatively new and less developed, and its economy may be adversely impacted by a slowdown in export growth. 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 Cash Balance Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	High Cash Balance Risk— when the Fund has a significant cash balance for a sustained period, the benefit to the Fund of any market upswing may likely be reduced, and the Fund’s performance may be adversely affected.
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.
Participatory Notes Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Participatory Notes Risk—an investment in participatory notes is subject to market risk. The performance results of participatory notes may not exactly replicate the performance of the underlying securities. An investment in participatory notes is also subject to counterparty risk, relating to the non-U.S. bank or broker-dealer that issues the participatory notes, and may be subject to liquidity risk.
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.
PRC Tax Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	PRC Tax Risk—the application of the tax laws and regulations of the PRC to income, including capital gains, derived from certain investments of the Fund remains unclear, and may well continue to evolve, possibly with retroactive effect. Any taxes imposed on the investments of the Fund pursuant to such laws and regulations will reduce the Fund’s overall returns.
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. Stocks in the industrials and information technology sectors may comprise a significant portion of the Fund's portfolio. The industrials sector may be affected by general economic trends, including employment, economic growth and interest rates, changes in consumer confidence and spending, government regulation, commodity prices and competitive pressures. The information technology sector may be affected by technological obsolescence, short product cycles, falling prices and profits, competitive pressures and general market conditions.
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.
Stock Connect Risk Member]
Prospectus [Line Items]
Risk [Text Block]	Stock Connect Risk—trading in China A-Shares through Stock Connect is subject to sudden changes in quota limitations, application of trading suspensions, differences in trading days between the People's Republic of China and Stock Connect, operational risk, clearing and settlement risk and regulatory and taxation risk.
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.
Variable Interest Entity Risk [Member]
Prospectus [Line Items]
Risk [Text Block]	Variable Interest Entity Risk—the Fund may gain investment exposure to certain Chinese companies through variable interest entity (“VIE”) structures. A VIE structure enables foreign investors, such as the Fund, to obtain investment exposure to a Chinese company in situations in which the Chinese government has limited or prohibited non-Chinese ownership of such company. A VIE does not have equity ownership in its corresponding China-based company but has claims to the China-based company’s profits and control of its assets through contractual arrangements. VIEs are a common industry practice and well known to officials and regulators in China; however, VIEs are not formally recognized under Chinese law. If the Chinese government takes action adversely affecting VIEs, the market value of the Fund’s associated portfolio holdings would likely suffer significant, detrimental, and possibly permanent consequences, which could result in substantial investment losses.
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.
Risk Nondiversified Status [Member]
Prospectus [Line Items]
Risk [Text Block]	Non-Diversified Fund Risk—the Fund is non-diversified and therefore a greater percentage of holdings may be focused in a small number of issuers or a single issuer, which can place the Fund at greater risk. Notwithstanding the Fund’s status as a “non-diversified” investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund intends to qualify each year as a regulated investment company accorded favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), which imposes its own diversification requirements that are less restrictive than the requirements applicable to “diversified” investment companies under the 1940 Act. The Fund’s intention to qualify as a regulated investment company may limit its pursuit of its investment strategy and its investment strategy could limit its ability to so qualify.

S000009865 [Member] Investment Risks - AMG Veritas Asia Pacific Fund

Dec. 31, 2025

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.

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.

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.

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.

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.

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.

Focused Investment Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Focused Investment Risk—to the extent the Fund invests a substantial portion of its assets in a relatively small number of securities or a particular market, industry, group of industries, country, region, group of countries, asset class or sector, it generally will be subject to greater risk than a fund that invests in a more diverse investment portfolio. In addition, the value of the Fund would be more susceptible to any single economic, market, political or regulatory occurrence affecting, for example, that particular market, industry, region or sector.

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.

Greater China. The Fund is particularly susceptible to risks in the Greater China region, which consists of Hong Kong, The People’s Republic of China and Taiwan, among other countries. Economies in the Greater China region are dependent on the economies of other countries and can be significantly affected by currency fluctuations and increasing competition from other emerging economies in Asia with lower costs. Adverse events in any one country within the region may impact the other countries in the region or Asia as a whole. Markets in the Greater China region can experience significant volatility due to social, economic, regulatory and political uncertainties. Significant portions of the Chinese securities markets may become rapidly illiquid, as Chinese issuers have the ability to suspend the trading of their equity securities, and have shown a willingness to exercise that option in response to market volatility and other events. U.S. or foreign government sanctions or other investment restrictions or intervention could negatively affect the implementation of the Fund’s investment strategies, for example by precluding the Fund from making certain investments or causing the Fund to sell investments at disadvantageous times. China has yet to develop comprehensive securities, corporate, or commercial laws, its market is relatively new and less developed, and its economy may be adversely impacted by a slowdown in export growth.

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 Cash Balance Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

High Cash Balance Risk— when the Fund has a significant cash balance for a sustained period, the benefit to the Fund of any market upswing may likely be reduced, and the Fund’s performance may be adversely affected.

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.

Participatory Notes Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Participatory Notes Risk—an investment in participatory notes is subject to market risk. The performance results of participatory notes may not exactly replicate the performance of the underlying securities. An investment in participatory notes is also subject to counterparty risk, relating to the non-U.S. bank or broker-dealer that issues the participatory notes, and may be subject to liquidity risk.

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.

PRC Tax Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

PRC Tax Risk—the application of the tax laws and regulations of the PRC to income, including capital gains, derived from certain investments of the Fund remains unclear, and may well

continue to evolve, possibly with retroactive effect. Any taxes imposed on the investments of the Fund pursuant to such laws and regulations will reduce the Fund’s overall returns.

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. Stocks in the industrials and information technology sectors may comprise a significant portion of the Fund's portfolio. The industrials sector may be affected by general economic trends, including employment, economic growth and interest rates, changes in consumer confidence and spending, government regulation, commodity prices and competitive pressures. The information technology sector may be affected by technological obsolescence, short product cycles, falling prices and profits, competitive pressures and general market conditions.

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.

Stock Connect Risk Member]

Prospectus [Line Items]

Risk [Text Block]

Stock Connect Risk—trading in China A-Shares through Stock Connect is subject to sudden changes in quota limitations, application of trading suspensions, differences in trading days between the People's Republic of China and Stock Connect, operational risk, clearing and settlement risk and regulatory and taxation risk.

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.

Variable Interest Entity Risk [Member]

Prospectus [Line Items]

Risk [Text Block]

Variable Interest Entity Risk—the Fund may gain investment exposure to certain Chinese companies through variable interest entity (“VIE”) structures. A VIE structure enables foreign investors, such as the Fund, to obtain investment exposure to a Chinese company in situations in which the Chinese government has limited or prohibited non-Chinese ownership of such company. A VIE does not have equity ownership in its corresponding China-based company but has claims to the China-based company’s profits and control of its assets through contractual arrangements. VIEs are a common industry practice and well known to officials and regulators in China; however, VIEs are not formally recognized under Chinese law. If the Chinese government takes action adversely affecting VIEs, the market value of the Fund’s associated portfolio holdings would likely suffer significant, detrimental, and possibly permanent consequences, which could result in substantial investment losses.

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.

Risk Nondiversified Status [Member]

Prospectus [Line Items]

Risk [Text Block]

Non-Diversified Fund Risk—the Fund is non-diversified and therefore a greater percentage of holdings may be focused in a small number of issuers or a single issuer, which can place the Fund at greater risk. Notwithstanding the Fund’s status as a “non-diversified” investment company under the Investment Company Act of 1940 (the “1940 Act”), the Fund intends to qualify each year as a regulated investment company accorded favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), which imposes its own diversification requirements that are less restrictive than the requirements applicable to “diversified” investment companies under the 1940 Act. The Fund’s intention to qualify as a regulated investment company may limit its pursuit of its investment strategy and its investment strategy could limit its ability to so qualify.