v3.26.1
S000093069 [Member] Investment Risks - AMG GW&K Securitized Bond SMA Shares
Dec. 31, 2025
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.
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.
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.
Changing Distribution Level Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Changing Distribution Level Risk—the Fund will normally receive income which may include interest, dividends and/or capital gains, depending upon its investments. The distribution amount paid by the Fund will vary and generally depends on the amount of income the Fund earns (less expenses) on its portfolio holdings, and capital gains or losses it recognizes. A decline in the Fund’s income or net capital gains arising from its investments may reduce its distribution level.
Derivatives Risks [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk—the use of derivatives involves costs, the risk that the value of derivatives may not correlate perfectly with their underlying assets, rates or indices, liquidity risk, and the risk of mispricing or improper valuation. The use of derivatives may not succeed for various reasons, and the complexity and rapidly changing structure of derivatives markets may increase the possibility of market losses.
Extension Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Extension Risk—during periods of rising interest rates, a debtor may pay back a bond or other fixed income security slower than expected or required, and the value of such security may fall.
Inflation Deflation Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Inflation/Deflation Risk—inflation risk is the risk that the value of assets or income from investments will be worth less in the future. Inflation rates may change frequently and drastically as a result of various factors and the Fund’s investments may not keep pace with inflation, which may result in losses to Fund investors or adversely affect the real value of shareholders’ investments in the Fund. As inflation rates increase, fixed income securities markets may experience heightened levels of interest rate volatility and liquidity risk. Deflation risk is the risk that the prices throughout the economy decline over time – the opposite of inflation. Deflation may have an adverse effect on the creditworthiness of issuers and may make issuer default more likely, which may result in a decline in the value of the Fund’s portfolio.
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.
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.
Prepayment Risks [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Prepayment Risk—a debtor may exercise its right to pay back a bond or other debt security earlier than expected or required during periods of decreasing interest rates.
Asset Backed and Mortgage Backed Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Asset-Backed and Mortgage-Backed Securities Risk—investments in asset-backed and mortgage-backed securities involve risk of severe credit downgrades, loss due to prepayments that occur earlier or later than expected, illiquidity and default.
Collateralized Loan Obligations and Other Collateralized Obligations Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Collateralized Loan Obligations and Other Collateralized Obligations Risk—the risks of investing in a CLO generally can be summarized as a combination of economic risks of the underlying loans combined with the risks associated with the CLO structure governing the priority of payments, and include interest rate risk, credit risk, liquidity risk, prepayment risk, and the risk of default of the underlying asset, among others.
Floating Rate Instrument Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Floating Rate Instrument Risk— changes in interest rates may affect the yield on the Fund’s investments in floating rate investments. Floating rate investments may decline in value if their interest rates do not rise as much, or as quickly, as interest rates in general. Conversely, a decline in interest rates may result in a reduction in income received from floating rate investments held by the Fund and may adversely affect the value of the Fund’s shares.
Leverage Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Leverage Risk—borrowing and some derivative investments such as futures, forward commitment transactions and swaps may increase volatility and magnify smaller adverse market movements into relatively larger losses.
U S Government Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Securities Risk—obligations issued by some U.S. Government agencies, authorities, instrumentalities, or sponsored enterprises such as Government National Mortgage Association (“GNMA”) are backed by the full faith and credit of the U.S. Government, while obligations issued by others, such as Federal National Mortgage Association (“FNMA”), Federal Home Loan Mortgage Corporation (“FHLMC”), and Federal Home Loan Banks (“FHLBs”), are not backed by the full faith and credit of the U.S. Government and are backed solely by the entity’s own resources or by the ability of the entity to borrow from the U.S. Treasury. If one of these agencies defaults on a loan, there is no guarantee that the U.S. Government will provide financial support.
Restricted Securities Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Restricted Securities Risk— investing in restricted securities (including, without limitation, Rule 144A securities) may reduce the liquidity of the Fund’s investments in the event that an adequate trading market does not exist for these securities. Limitations on the resale of restricted securities could adversely
affect the marketability of the securities, and the Fund may be unable to sell the security at the desired time or price, if at all. The purchase price and subsequent valuation of restricted securities normally reflect a discount, which may be significant, from the market price of comparable unrestricted securities for which a liquid trading market exists.
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.
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.