Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	AMG Funds I
Prospectus Date	rr_ProspectusDate	Mar. 01, 2020
AMG FQ Global Risk-Balanced Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	AMG FQ Global Risk-Balanced Fund
Objective [Heading]	rr_ObjectiveHeading	INVESTMENT OBJECTIVE
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The AMG FQ Global Risk-Balanced Fund’s (the “Fund”) investment objective is to maximize total return.
Expense [Heading]	rr_ExpenseHeading	FEES AND EXPENSES OF THE FUND
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The table below describes the fees and expenses that you may pay if you buy and hold shares of the Fund. If you transact in Class I shares of the Fund through a financial intermediary, you may be required to pay a commission to the financial intermediary for effecting such transactions. Such commissions are charged by the financial intermediary and are not reflected in the table or Expense Example below.
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination	rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination	March 1, 2021
Portfolio Turnover [Heading]	rr_PortfolioTurnoverHeading	PORTFOLIO TURNOVER
Portfolio Turnover [Text Block]	rr_PortfolioTurnoverTextBlock	The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 15% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	15.00%
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Expense information has been restated to reflect current fees.
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees	The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements do not correlate to the ratios of expenses to average net assets in the Financial Highlights section of this Prospectus, which reflect only the operating expenses of the Fund and do not include fees and expenses of any acquired fund.
Expense Example [Heading]	rr_ExpenseExampleHeading	EXPENSE EXAMPLE
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	This Example will help you compare the cost of investing in the Fund to the cost of investing in other mutual funds. The Example makes certain assumptions. It assumes that you invest $10,000 as an initial investment in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. It also assumes that your investment has a 5% total return each year and the Fund’s operating expenses remain the same. The Example includes the Fund’s contractual expense limitation through March 1, 2021. Although your actual costs may be higher or lower, based on the above assumptions, your costs would be:
Strategy [Heading]	rr_StrategyHeading	PRINCIPAL INVESTMENT STRATEGIES
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to provide a diversified, risk-balanced global market portfolio. The Fund attempts to balance risk and return by gaining exposure, generally through derivative instruments, to global equities, debt, currency markets, and commodities utilizing a proprietary dynamic asset allocation process. The Fund will invest in issuers, and/or have investments that expose the Fund to issuers, organized, located, or doing a substantial amount of business in a minimum of three countries, including the United States. Under normal circumstances, the Fund will invest at least 40% of its net assets, plus the amount of any borrowing for investment purposes, in issuers organized, located, or doing a substantial amount of business outside the United States, including investments (such as futures contracts or underlying funds) that provide the Fund with investment exposure to such issuers. First Quadrant, L.P.’s (“First Quadrant” or the “Subadviser”) proprietary investment process is designed to seek to provide a diversified, risk-balanced global market portfolio. First Quadrant utilizes a risk-based approach and seeks to rebalance the Fund to manage portfolio risk. Applying this process, the Fund seeks to provide greater capital loss protection during down markets than traditional balanced portfolios, as well as participate in market gains. Generally, the Fund intends to allocate a large portion of its investments across some or all of the following asset classes: Inflation-Protected Securities — Generally through investments in exchange traded funds (“ETFs”) and cash sovereign bonds. Sovereign (Foreign Country) Debt — Generally through futures on foreign country debt indices and cash sovereign bonds, which may be used to increase income or hedge against the Fund’s risks related to global equity exposure. Global (U.S. and Non-U.S.) Equities — Generally through equity investments and futures on equity country indices, although the Fund may also seek to gain exposure to various sectors by investing in ETFs. High Yield Bonds — Generally through investments in ETFs and derivative instruments such as total return swaps, which may be used for diversification or other purposes. Commodities — Generally through investments exposed to companies in the commodities sector and instruments linked to a commodity index or futures contract(s), particularly ETFs and exchange-traded notes (“ETNs”). Currency Markets — Generally through the use of derivative instruments such as foreign currency forwards on developed or emerging market currencies. In addition to the above, the Fund generally expects to have investment exposure to developed and emerging markets, small capitalization securities, and real estate investment trusts (“REITs”). In selecting equity investments for the Fund, First Quadrant is not constrained by any particular investment style or capitalization range. In selecting debt investments for the Fund, First Quadrant has the flexibility to invest in debt-related investments of any credit quality and with any duration. The Fund may achieve long and short exposure to global equity, bond, and currency markets through a wide range of derivative instruments and direct investments. The Fund may take short positions in futures, including futures on indices and interest rate futures. The Fund may also invest directly in global equity securities and global fixed-income securities. In addition, the Fund may invest in commodity-linked derivative instruments and investment vehicles that exclusively invest in various commodities or have economic exposure to commodities.
Risk [Heading]	rr_RiskHeading	PRINCIPAL RISKS
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	There is the risk that you may lose money on your investment. All investments carry a certain amount of risk, and the Fund cannot guarantee that it will achieve its investment objective. 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. Below are some of the risks of investing in the Fund. The Fund may be exposed to the following risks directly, by investing in securities, or indirectly, through the use of derivatives and ETFs. The risks are presented in an order intended to facilitate readability and their order does not imply that the realization of one risk is more likely to occur than another risk or likely to have a greater adverse impact than another risk. The significance of any specific risk to an investment in the Fund will vary over time, depending on the composition of the Fund’s portfolio, market conditions, and other factors. You should read all of the risk information presented below carefully, because any one or more of these risks may result in losses to the Fund. Market Risk—market prices of investments held by the Fund may fall rapidly or unpredictably due to a variety of factors, including economic, political, or market conditions or in response to events that affect particular industries or companies. Asset Allocation Risk—the Fund’s investments may not be allocated in the best performing asset classes. 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. 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, 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. Hedging Risk—there is no guarantee that hedging strategies will be successful. For example, changes in the value of a hedging transaction may not completely offset changes in the value of the assets and liabilities being hedged. Hedging transactions involve costs and may result in losses. Commodities Exposure Risk—exposure to commodities through investments exposed to companies in the commodities sector, commodity futures contracts, or otherwise, may result in losses for the Fund. Commodity prices, the value of stocks of companies exposed to commodities, and commodity futures prices, and therefore ETNs exposed to such commodity futures, can be extremely volatile and are affected by a wide range of factors, including market movements, supply and demand imbalances and inflationary trends. Credit and Counterparty Risk—the issuer of bonds, ETNs or other debt securities or a counterparty to a derivatives contract 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. 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—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. Exchange-Traded Fund Risk—because exchange-traded funds incur their own costs, investing in them could result in a higher cost to the investor. Exchange-Traded Note Risk—the value of an ETN may be influenced by fluctuations in the values of the underlying assets or instruments, time to maturity, level of supply and demand for the ETN, volatility and lack of liquidity in the underlying markets, changes in applicable interest rates, and changes in the issuer’s credit rating. The Fund bears any fees and expenses associated with investment in ETNs. There may be restrictions on the Fund’s right to redeem its investment in an ETN meant to be held to maturity, and it may be difficult for the Fund to sell its ETN holdings. 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. 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. Inflation Risk—the risk that the value of assets or income from investments will be worth less in the future. 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. 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. Leverage Risk—borrowing and some derivative investments such as futures, forward commitment transactions and swaps may magnify smaller adverse market movements into relatively larger losses. 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. Model and Data Risk—when a quantitative model (“Model”) or information or data (“Data”) used in managing the Fund contains an error, or is incorrect or incomplete, any investment decision made in reliance on the Model or Data may not produce the desired results and the Fund may realize losses. In addition, any hedging based on a faulty Model or Data may prove to be unsuccessful. Furthermore, the success of a Model that is predictive in nature is dependent largely on the accuracy and reliability of the supplied historical data. All Models are susceptible to input errors or errors in design, which may cause the resulting output to be faulty. 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. Real Estate Industry Risk—investments in the Fund may be subject to many of the same risks as a direct investment in real estate. The stock prices of companies in the real estate industry, including REITs, are typically sensitive to changes in real estate values, property taxes, interest rates, cash flow of underlying real estate assets, occupancy rates, government regulations affecting zoning, land use, and rents, as well as the management skill and creditworthiness of the issuer. REITs also depend generally on their ability to generate cash flow to make distributions to shareholders or unitholders and are subject to the risk of failing to qualify for favorable tax treatment under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”). Short Sales Risk—a short sale of a security involves the theoretical risk of unlimited loss because of potential unlimited increases in the market price of the security sold short. The Fund’s use of short sales, in certain circumstances, can result in significant losses. 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. Tax Risk—the Fund intends to qualify as a regulated investment company accorded special tax treatment under the Internal Revenue Code of 1986, as amended. The Fund’s investments in commodities or commodity-related investments can be limited by the Fund’s intention to qualify as a regulated investment company, and can limit the Fund’s ability to so qualify. 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.
Risk Lose Money [Text]	rr_RiskLoseMoney	There is the risk that you may lose money on your investment.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	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.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	PERFORMANCE
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following performance information illustrates the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s performance compares to that of a broad-based securities market index, the S&P 500 Index, and to a composite index, 60% MSCI World Index and 40% FTSE World Government Bond Index (“Composite Index”), which more accurately reflects the composition of the Fund’s portfolio. The Composite Index is calculated on both a hedged and unhedged basis, with respect to currency exchange rates, in the accompanying table. As always, past performance of the Fund (before and after taxes) is not an indication of how the Fund will perform in the future. Effective October 1, 2016, outstanding Institutional Class shares (formerly shares of the Managers Fremont Global Fund’s sole share class, which were reclassified and redesignated as Institutional Class shares on January 1, 2010), Investor Class shares, and Service Class shares of the Fund were renamed Class Z, Class N, and Class I shares, respectively. To obtain updated monthly performance information please visit www.amgfunds.com or call 800.548.4539.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following performance information illustrates the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and by showing how the Fund’s performance compares to that of a broad-based securities market index, the S&P 500 Index, and to a composite index, 60% MSCI World Index and 40% FTSE World Government Bond Index (“Composite Index”), which more accurately reflects the composition of the Fund’s portfolio.
Performance Additional Market Index [Text]	rr_PerformanceAdditionalMarketIndex	60% MSCI World Index and 40% FTSE World Government Bond Index (“Composite Index”), which more accurately reflects the composition of the Fund’s portfolio. The Composite Index is calculated on both a hedged and unhedged basis, with respect to currency exchange rates, in the accompanying table.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800.548.4539
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	www.amgfunds.com
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	As always, past performance of the Fund (before and after taxes) is not an indication of how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Calendar Year Total Returns as of 12/31/19 (Class Z)
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	Best Quarter: 10.76% (1st Quarter 2019) Worst Quarter: -8.70% (4th Quarter 2018)
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns as of 12/31/19
Performance Table Uses Highest Federal Rate	rr_PerformanceTableUsesHighestFederalRate	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes.
Performance Table Not Relevant to Tax Deferred	rr_PerformanceTableNotRelevantToTaxDeferred	Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”).
Performance Table One Class of after Tax Shown [Text]	rr_PerformanceTableOneClassOfAfterTaxShown	After-tax returns are shown for Class Z shares only, and after-tax returns for Class N and Class I  shares will vary.
Performance Table Narrative	rr_PerformanceTableNarrativeTextBlock	After-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on an investor’s tax situation and may differ from those shown. After-tax returns are not relevant to investors who hold their Fund shares through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts (“IRAs”). After-tax returns are shown for Class Z shares only, and after-tax returns for Class N and Class I  shares will vary.
AMG FQ Global Risk-Balanced Fund | Class N
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.60%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.55%	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.21%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.61%	[2]
Fee Waiver and Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements	rr_NetExpensesOverAssets	1.50%	[2],[3]
1 Year	rr_ExpenseExampleYear01	$ 153
3 Years	rr_ExpenseExampleYear03	497
5 Years	rr_ExpenseExampleYear05	866
10 Years	rr_ExpenseExampleYear10	$ 1,902
1 Year	rr_AverageAnnualReturnYear01	19.80%
5 Years	rr_AverageAnnualReturnYear05	5.67%
10 Years	rr_AverageAnnualReturnYear10
Since Inception	rr_AverageAnnualReturnSinceInception	5.92%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 01, 2010
AMG FQ Global Risk-Balanced Fund | Class I
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.60%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.55%	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.21%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.36%	[2]
Fee Waiver and Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements	rr_NetExpensesOverAssets	1.25%	[2],[3]
1 Year	rr_ExpenseExampleYear01	$ 127
3 Years	rr_ExpenseExampleYear03	420
5 Years	rr_ExpenseExampleYear05	734
10 Years	rr_ExpenseExampleYear10	$ 1,626
1 Year	rr_AverageAnnualReturnYear01	20.06%
5 Years	rr_AverageAnnualReturnYear05	6.03%
10 Years	rr_AverageAnnualReturnYear10
Since Inception	rr_AverageAnnualReturnSinceInception	6.30%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 01, 2010
AMG FQ Global Risk-Balanced Fund | Class Z
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.60%
Distribution and Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.40%	[1]
Acquired Fund Fees and Expenses	rr_AcquiredFundFeesAndExpensesOverAssets	0.21%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.21%	[2]
Fee Waiver and Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.11%)	[3]
Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements	rr_NetExpensesOverAssets	1.10%	[2],[3]
1 Year	rr_ExpenseExampleYear01	$ 112
3 Years	rr_ExpenseExampleYear03	373
5 Years	rr_ExpenseExampleYear05	654
10 Years	rr_ExpenseExampleYear10	$ 1,456
2010	rr_AnnualReturn2010	12.09%
2011	rr_AnnualReturn2011	7.94%
2012	rr_AnnualReturn2012	9.80%
2013	rr_AnnualReturn2013	(1.95%)
2014	rr_AnnualReturn2014	6.07%
2015	rr_AnnualReturn2015	(5.88%)
2016	rr_AnnualReturn2016	14.31%
2017	rr_AnnualReturn2017	15.87%
2018	rr_AnnualReturn2018	(10.13%)
2019	rr_AnnualReturn2019	20.31%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	Best Quarter:
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Mar. 31, 2019
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	10.76%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	Worst Quarter:
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Dec. 31, 2018
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(8.70%)
1 Year	rr_AverageAnnualReturnYear01	20.31%
5 Years	rr_AverageAnnualReturnYear05	6.16%
10 Years	rr_AverageAnnualReturnYear10	6.42%
Since Inception	rr_AverageAnnualReturnSinceInception		[4]
AMG FQ Global Risk-Balanced Fund | Return After Taxes on Distributions | Class Z
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.45%
5 Years	rr_AverageAnnualReturnYear05	5.28%
10 Years	rr_AverageAnnualReturnYear10	5.38%
Since Inception	rr_AverageAnnualReturnSinceInception		[4]
AMG FQ Global Risk-Balanced Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class Z
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	12.02%
5 Years	rr_AverageAnnualReturnYear05	4.42%
10 Years	rr_AverageAnnualReturnYear10	4.65%
Since Inception	rr_AverageAnnualReturnSinceInception		[4]
AMG FQ Global Risk-Balanced Fund | 60% MSCI World/40% FTSE World Government Bond - Hedged (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.53%
5 Years	rr_AverageAnnualReturnYear05	6.16%
10 Years	rr_AverageAnnualReturnYear10	6.74%
Since Inception	rr_AverageAnnualReturnSinceInception	6.74%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 01, 2010
AMG FQ Global Risk-Balanced Fund | 60% MSCI World/40% FTSE World Government Bond - UnHedged (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	18.68%
5 Years	rr_AverageAnnualReturnYear05	6.23%
10 Years	rr_AverageAnnualReturnYear10	6.61%
Since Inception	rr_AverageAnnualReturnSinceInception	6.61%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 01, 2010
AMG FQ Global Risk-Balanced Fund | S&P 500® Index (reflects no deduction for fees, expenses, or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	31.49%
5 Years	rr_AverageAnnualReturnYear05	11.70%
10 Years	rr_AverageAnnualReturnYear10	13.56%
Since Inception	rr_AverageAnnualReturnSinceInception	13.57%	[4]
Inception Date	rr_AverageAnnualReturnInceptionDate	Jan. 01, 2010

[1] Expense information has been restated to reflect current fees.

[2] The Total Annual Fund Operating Expenses and Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements do not correlate to the ratios of expenses to average net assets in the Financial Highlights section of this Prospectus, which reflect only the operating expenses of the Fund and do not include fees and expenses of any acquired fund.

[3] AMG Funds LLC (the “Investment Manager”) has contractually agreed, through at least March 1, 2021, to waive management fees and/or pay or reimburse the Fund’s expenses in order to limit Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements (exclusive of taxes, interest (including interest incurred in connection with bank and custody overdrafts and in connection with securities sold short), shareholder servicing fees, distribution and service (12b-1) fees, brokerage commissions and other transaction costs, dividends payable with respect to securities sold short, acquired fund fees and expenses, and extraordinary expenses) of the Fund to the annual rate of 0.89% of the Fund’s average daily net assets (this annual rate or such other annual rate that may be in effect from time to time, the “Expense Cap”), subject to later reimbursement by the Fund in certain circumstances. In general, for a period of up to 36 months after the date any amounts are paid, waived or reimbursed by the Investment Manager, the Investment Manager may recover such amounts from the Fund, provided that such repayment would not cause the Fund’s Total Annual Fund Operating Expenses After Fee Waiver and Expense Reimbursements (exclusive of the items noted in the parenthetical above) to exceed either (i) the Expense Cap in effect at the time such amounts were paid, waived or reimbursed, or (ii) the Expense Cap in effect at the time of such repayment by the Fund. The contractual expense limitation may only be terminated in the event the Investment Manager or a successor ceases to be the investment manager of the Fund or a successor fund, by mutual agreement between the Investment Manager and the AMG Funds I Board of Trustees or in the event of the Fund’s liquidation unless the Fund is reorganized or is a party to a merger in which the surviving entity is successor to the accounting and performance information of the Fund.

[4] Class N, Class I and Index performance shown reflects performance since the inception date of the Fund's Class N and Class I shares on January 1, 2010.