Class I and Class Z [Member] Investment Strategy - Class I and Class Z [Member] - AMG Yacktman Special Opportunities Fund	Dec. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	In pursuing the objective of long-term capital appreciation, the Fund employs a value-oriented investment approach. The Fund’s investment strategy consists of purchasing securities where Yacktman Asset Management LP (“Yacktman” or the “Subadviser”) believes the current market price offers a meaningful discount to intrinsic value (with value measured on an absolute basis, rather than on a relative basis to the broader market). The Subadviser employs a fundamental, bottom-up selection process. The Subadviser’s fundamental analysis consists of examining such factors as a company’s history, business model, earnings potential, management team, and industry position. Typical investments will often take into account, but not be limited to, the following factors: •Businesses the Subadviser believes have a durable competitive position exhibited by high market share, profitability or returns on capital•Management teams with a track record of strong execution and rational capital allocation•Low purchase price in relation to a company’s asset value, earnings potential or cash generation ability Securities are purchased when the Subadviser believes they offer an attractive forward rate of return, after adjusting for business quality and risk. Investments are generally sold when the Subadviser believes the price of the security meets or exceeds its intrinsic value, the Subadviser’s investment criteria are no longer met, or the Subadviser believes more attractive investments become available. The Fund invests primarily in domestic and foreign equity securities, including emerging market securities, of any market capitalization range. The Fund, however, may also invest in domestic and foreign debt securities. The Fund is not precluded from investing in a growth stock if the Subadviser believes such security otherwise meets its investment criteria. The Fund’s investments in equity securities may include common stocks, preferred stocks, convertible preferred stocks, warrants, options, American Depositary Receipts (“ADRs”), Global Depositary Receipts (“GDRs”) and other depositary receipts of non-U.S. listed companies. The Fund’s investments in debt securities may include U.S. Treasury notes and bonds, investment grade corporate debt securities, convertible debt securities and debt securities below investment grade (high yield or junk bonds). The Fund may invest up to 20% of its assets in such debt securities, including junk bonds, in any proportion provided that the total invested does not exceed the 20% threshold at the time of investment. At times, depending on market and other conditions, and at the discretion of the Subadviser, the Fund may invest a substantial portion of its assets in a small number of issuers, business sectors or industries. The Fund is non-diversified. For hedging and investment purposes, the Fund may engage in short sales of securities, including short sales of securities the Fund does not own. The Subadviser will generally not hedge the Fund’s currency exposure. However, the Subadviser may hedge a portion of the Fund’s currency exposure on a selective basis as it deems appropriate in an effort to reduce currency risk with respect to specific securities transactions or currencies. In doing so, the Subadviser may use derivatives such as foreign exchange forwards and/or foreign currency options or similar instruments. Under normal market conditions, the majority of the Fund’s assets will be allocated to equity securities. However, the Fund may not be fully invested at all times, and may often hold a portion of total assets in cash and cash equivalents, which at times may be significant. The Fund’s cash level at any point typically relates to the Subadviser’s individual security selection, and therefore will be a function of the number of opportunities that meet the Subadviser’s investment criteria.

In pursuing the objective of long-term capital appreciation, the Fund employs a value-oriented investment approach. The Fund’s investment strategy consists of purchasing securities where Yacktman Asset Management LP (“Yacktman” or the “Subadviser”) believes the current market price offers a meaningful discount to intrinsic value (with value measured on an absolute basis, rather than on a relative basis to the broader market).

The Subadviser employs a fundamental, bottom-up selection process. The Subadviser’s fundamental analysis consists of examining such factors as a company’s history, business model, earnings potential, management team, and industry position. Typical investments will often take into account, but not be limited to, the following factors:

Securities are purchased when the Subadviser believes they offer an attractive forward rate of return, after adjusting for business quality and risk. Investments are generally sold when the Subadviser believes the price of the security meets or exceeds its intrinsic value, the Subadviser’s investment criteria are no longer met, or the Subadviser believes more attractive investments become available.

The Fund invests primarily in domestic and foreign equity securities, including emerging market securities, of any market capitalization range. The Fund, however, may also invest in domestic and foreign debt securities. The Fund is not precluded from investing in a growth stock if the Subadviser believes such security otherwise meets its investment criteria.

The Fund’s investments in equity securities may include common stocks, preferred stocks, convertible preferred stocks, warrants, options, American Depositary Receipts (“ADRs”), Global Depositary Receipts (“GDRs”) and other depositary receipts of non-U.S. listed companies.

The Fund’s investments in debt securities may include U.S. Treasury notes and bonds, investment grade corporate debt securities, convertible debt securities and debt securities below investment grade (high yield or junk bonds). The Fund may invest up to 20% of its assets in such debt securities, including junk bonds, in any proportion provided that the total invested does not exceed the 20% threshold at the time of investment.

At times, depending on market and other conditions, and at the discretion of the Subadviser, the Fund may invest a substantial portion of its assets in a small number of issuers, business sectors or industries. The Fund is non-diversified.

For hedging and investment purposes, the Fund may engage in short sales of securities, including short sales of securities the Fund does not own.

The Subadviser will generally not hedge the Fund’s currency exposure. However, the Subadviser may hedge a portion of the Fund’s currency exposure on a selective basis as it deems appropriate in an effort to reduce currency risk with respect to specific securities transactions or currencies. In doing so, the Subadviser may use derivatives such as foreign exchange forwards and/or foreign currency options or similar instruments.

Under normal market conditions, the majority of the Fund’s assets will be allocated to equity securities. However, the Fund may not be fully invested at all times, and may often hold a portion of total assets in cash and cash equivalents, which at times may be significant. The Fund’s cash level at any point typically relates to the Subadviser’s individual security selection, and therefore will be a function of the number of opportunities that meet the Subadviser’s investment criteria.