v3.26.1
Investment Risks
Aug. 25, 2026
F/m Accumulator BDC Fund | Active Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Active Management Risk. The Fund is actively managed using proprietary investment strategies and processes. There can be no guarantee that these strategies and processes will be successful or that the Fund will achieve its investment objective.
F/m Accumulator BDC Fund | Affiliated Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
Affiliated Fund Risk. Affiliated fund risk is the risk that the Adviser may select Underlying Funds and/or investments for the Fund based on its own financial interests or other business considerations rather than the Fund’s interests. The Adviser may be subject to potential conflicts of interest in selecting the Underlying Funds because affiliated Underlying Funds pay an advisory fee to the Adviser based on their assets, the fees paid to the Adviser by some affiliated Underlying Funds may be higher than those paid by other Underlying Funds or the Underlying Funds may be in need of assets to enhance their appeal to other investors, liquidity and trading and/or to enable them to carry out their investment strategies. However, the Adviser is a fiduciary to the Fund and is legally obligated to act in the Fund’s best interest when selecting Underlying Funds.
F/m Accumulator BDC Fund | Asset Class Risk  
Prospectus [Line Items]  
Risk [Text Block]
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market, or other asset classes.
F/m Accumulator BDC Fund | BDC Risk  
Prospectus [Line Items]  
Risk [Text Block]
BDC Risk. Although many BDC loans and investments are to mature companies, a BDC may also invest in and lend to smaller and developing companies as well as companies that are experiencing financial crises. Investments in these types of companies may present a greater risk of loss due to the companies’ youth, limited track records and limited access to capital markets, and these companies also may be susceptible to competition and economic and market changes due to limited products and market shares. In addition, the securities of smaller and developing companies and companies experiencing financial crises typically have limited liquidity and may be more difficult to value. Those companies with limited capital resources may have a greater risk of default on their debt and may not be able to distribute dividends on any preferred and common stock. BDCs typically use leverage (e.g., borrowing and the issuance of fixed income and preferred securities) to finance their own operations, which magnifies gains and losses on amounts invested by the BDC and increases the risks that a BDC may suffer significant losses during periods of acute market fluctuation. The Fund has no control over management of a BDC or the investments made by BDCs, and BDCs are subject to additional risks, including periods when their shares trade at a discount to their net asset value, or conditions when public market liquidity is low. Some BDCs invest substantially, or even exclusively, in one sector or industry group and therefore carry risk of being susceptible to adverse conditions and economic or regulatory circumstances affecting the specific sector or industry group, which may increase volatility and risk. The Fund may be limited by provisions of the 1940 Act that generally limit the amount the Fund can invest in any one closed-end fund, including any single BDC, to 3% of the closed-end fund’s total outstanding stock, and the Fund may be required to vote shares of the BDC held by the Fund in the same general proportion as shares held by other shareholders of the BDC. The Fund will indirectly bear its proportionate share of any management and other operating expenses, and of any performance-based or incentive fees, charged by the BDCs in which it invests, in addition to the management fee and other expenses of the Fund.

 

BDCs generally invest in less mature U.S. private companies or thinly-traded U.S. public companies which involve greater risk than well-established publicly-traded companies. While BDCs are generally expected to generate income in the form of dividends, certain BDCs during certain periods of time may not generate such income. A BDC’s incentive fee may be very high, vary from year-to-year and be payable even if the value of the BDC’s portfolio declines in a given time period. Incentive fees may create an incentive for a BDC’s manager to make investments that are risky or more speculative than would be the case in the absence of such compensation arrangements, and may also encourage the BDC’s manager to use a greater degree of leverage to increase the return on the BDC’s investments. The use of leverage by BDCs magnifies gains and losses on amounts invested and increases the risks associated with investing in BDCs. A BDC may make investments with a larger amount of risk of volatility and loss of principal than other investment options and may also be highly speculative and aggressive.

F/m Accumulator BDC Fund | Call Risk  
Prospectus [Line Items]  
Risk [Text Block]
Call Risk. During periods of falling interest rates, an issuer of a callable bond held by an Underlying Fund may “call” or repay the security before its stated maturity, and the Underlying Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund’s performance, or in securities with greater risks or with other less favorable features.
F/m Accumulator BDC Fund | Cash or Cash Equivalents Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cash or Cash Equivalents Risk. At any time, the Fund may have significant investments in cash or cash equivalents. When a substantial portion of a portfolio is held in cash or cash equivalents, there is the risk that the value of the cash account, including interest, will not keep pace with inflation, thus reducing purchasing power over time. Additionally, in rising markets, holding cash or cash equivalents may adversely affect the Fund’s performance and the Fund may not achieve its investment objectives.
F/m Accumulator BDC Fund | Common Stock Risk  
Prospectus [Line Items]  
Risk [Text Block]
Common Stock Risk. The Fund will invest in common stock issued by BDCs. Common stock represents an ownership interest in a company. The value of a company’s stock, including a BDC, may fall or fail to rise as a result of factors directly relating to that company, such as decisions made by its management or lower demand for the company’s products or services. A stock’s value may also fall because of factors affecting not just the company, but also other companies in the same industry or in a number of different industries, such as increases in production costs. The value of a BDC’s stock may also be affected by changes in financial markets that are relatively unrelated to the company or its industry, such as changes in interest rates, currency exchange rates or inflation rates. In addition, a BDC’s stock generally pays dividends only after the BDC has invested in other companies and makes required payments to holders of its bonds and other debt. For this reason, the value of a company’s stock will usually react more strongly than its bonds and other debt to actual or perceived changes in the company’s financial condition or prospects.
F/m Accumulator BDC Fund | Concentration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in a particular issue, issuer or issuers, country, market segment, or asset class.
F/m Accumulator BDC Fund | Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Credit Risk. The value of your investment in the Fund may change in response to changes in the credit ratings of the Fund’s portfolio securities, including with respect to BDCs and Underlying Funds. Generally, investment risk and price volatility increase as a security’s credit rating declines. The financial condition of an issuer of a fixed income security held by the Fund or a BDC or Underlying Fund may cause it to default or become unable to pay interest or principal due on the security.
F/m Accumulator BDC Fund | Cyber Security Risk  
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Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to the Fund’s assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent the Fund’s investors from purchasing, redeeming or exchanging Shares or receiving distributions. While the Fund and the Adviser have established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Further, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, or issuers of securities in which the Fund invests. The Fund and the Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or the Adviser. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders. Issuers of securities in which the Fund invests are also subject to cyber security risks, and the value of these securities could decline if the issuers experience cyberattacks or other cyber-failures.
F/m Accumulator BDC Fund | Derivatives Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk. Derivatives and other similar instruments (referred to collectively as “derivatives”) are financial instruments whose values are based on the value of one or more reference assets or indicators, such as a security, currency, interest rate, or index. The Fund’s use of derivatives involves risks different from, and possibly greater than, the risks associated with investing directly in securities and other more traditional investments. Moreover, although the value of a derivative is based on an underlying asset or indicator, a derivative typically does not carry the same rights as would be the case if the Fund invested directly in the underlying securities, currencies or other assets.

 

Derivatives are subject to a number of risks, such as potential changes in value in response to market developments or, in the case of “over-the-counter” derivatives, as a result of a counterparty’s credit quality and the risk that a derivative transaction may not have the effect the Adviser anticipated. Derivatives also involve the risk of mispricing or improper valuation and the risk that changes in the value of a derivative may not achieve the desired correlation with the underlying asset or indicator. Derivative transactions can create investment leverage and may be highly volatile, and the Fund could lose more than the amount it invests. The use of derivatives may increase the amount and affect the timing and character of taxes payable by shareholders of the Fund.

 

Many derivative transactions are entered into “over-the-counter” without a central clearinghouse; as a result, the value of such a derivative transaction will depend on, among other factors, the ability and the willingness of the Fund’s counterparty to perform its obligations under the transaction. If a counterparty were to default on its obligations, the Fund’s contractual remedies against such counterparty may be subject to bankruptcy and insolvency laws, which could affect the Fund’s rights as a creditor (e.g., the Fund may not receive the net amount of payments that it is contractually entitled to receive). Counterparty risk also refers to the related risks of having concentrated exposure to such a counterparty. A liquid secondary market may not always exist for the Fund’s derivative positions at any time, and the Fund may not be able to initiate or liquidate a swap position at an advantageous time or price, which may result in significant losses. The Fund may also face the risk that it may not be able to meet margin and payment requirements and maintain a derivatives position.

 

Derivatives are also subject to operational and legal risks. Operational risk generally refers to risk related to potential operational issues, including documentation issues, settlement issues, system failures, inadequate controls, and human errors. Legal risk generally refers to insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract.

F/m Accumulator BDC Fund | Derivatives Counterparty Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Counterparty Risk. A loss may be sustained as a result of the failure of another party to a contract (usually referred to as a “counterparty”) to make required payments, fulfill its contractual obligations or otherwise comply with a contract’s terms because of the financial condition of the counterparty (i.e., financial difficulties or insolvency), market activities and developments, the counterparty being unable or unwilling to perform under the contract or other reasons. In a swap agreement, the Fund bears the risk of loss of the amount expected to be received under the agreement in the event of the default or bankruptcy of a counterparty. These risks are heightened and may materially impact the Fund’s ability to achieve its investment objective given that the Fund may enter into swap agreements with one or a limited number of counterparties. The Fund’s use of one or a limited number of counterparties increases the Fund’s exposure to counterparty credit risk. Credit risk refers to the possibility that the counterparty will be unable and/or unwilling to honor its obligations and/or default completely on the derivative transaction. Swap agreements also may be considered to be illiquid. Further, there is a risk that no suitable counterparties are willing to enter into, or continue to enter into, transactions with the Fund and, as a result, the Fund may not be able to achieve its investment objective.
F/m Accumulator BDC Fund | Duration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Duration Risk. Duration is a measure of the price sensitivity of a debt security or portfolio to interest rate changes. Duration risk is the risk that longer-duration debt securities will be more volatile and thus more likely to decline in price, and to a greater extent, in a rising interest rate environment than shorter-duration debt securities.
F/m Accumulator BDC Fund | Equity Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Equity Securities Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the markets in which the issuers of securities held by the Fund participate, or factors relating to specific issuers in which the Fund invests. Equity securities are subordinated to preferred securities and debt in a company’s capital structure with respect to priority to a share of corporate income, and therefore will be subject to greater dividend risk than preferred securities or debt instruments. In addition, while broad market measures of equity securities have historically generated higher average returns than fixed income securities, equity securities have generally also experienced significantly more volatility in those returns.
F/m Accumulator BDC Fund | ETF Risk  
Prospectus [Line Items]  
Risk [Text Block]
ETF Risk. The Fund is an ETF, and, as a result of an ETF’s structure, it is exposed to the following risks:

 

oAuthorized Participants, Market Makers and Liquidity Providers Concentration Risk. Only an authorized participant (“AP”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that are institutional investors and may act as APs. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent either of the following events occur, there may be significantly diminished trading in Fund Shares, Fund Shares may trade at a material discount to net asset value (“NAV”), and Fund Shares may possibly face delisting: (i) if APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services, or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform their functions. These events, among others, may lead to Fund Shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than the NAV when you buy Shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those Shares in the secondary market. A diminished market for an ETF’s shares substantially increases the risk that a shareholder may pay considerably more or receive significantly less than the underlying value of the ETF shares bought or sold. In periods of market volatility, APs, market makers and/or liquidity providers may be less willing to transact in Fund Shares.

 

oSecondary Market Trading Risk. Although Shares are intended to be listed on a national securities exchange, The Nasdaq Stock Market LLC (the “Exchange”), and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Shares on the Exchange may be halted. During periods of market stress, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines.

 

oShares May Trade at Prices Other Than NAV Risk. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Shares trade on a stock exchange at prices at, above, or below the Fund’s most recent NAV. The Fund’s NAV is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings. The trading price of the Shares fluctuates continuously throughout trading hours on the exchange, based on both the relative market supply of, and demand for, the Shares and the underlying value of the Fund’s portfolio holdings. As a result, the trading prices of the Shares may deviate from the Fund’s NAV. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. Any of these factors, among others, may lead to the Shares trading at a premium or discount to NAV.

 

To the extent the Fund invests in Underlying Funds that are ETFs, the Fund will be further exposed to the above ETF risks.

F/m Accumulator BDC Fund | Floating Rate Risk for BDCs  
Prospectus [Line Items]  
Risk [Text Block]
Floating Rate Risk for BDCs. The BDCs in which the Fund invests or in which an Underlying Fund invests may invest in floating rate securities, which are instruments in which the interest rate payable on an obligation fluctuates on a periodic basis based upon changes in an interest rate benchmark. As a result, the yield on such a security will generally decline in a falling interest rate environment, causing the BDC, and by extension, the Fund, to experience a reduction in the income it receives from the security.
F/m Accumulator BDC Fund | Futures Risk  
Prospectus [Line Items]  
Risk [Text Block]
Futures Risk. Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.
F/m Accumulator BDC Fund | High Portfolio Turnover Risk  
Prospectus [Line Items]  
Risk [Text Block]
High Portfolio Turnover Risk. Active and frequent trading of the Fund’s portfolio securities may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.
F/m Accumulator BDC Fund | Income Risk  
Prospectus [Line Items]  
Risk [Text Block]
Income Risk. Under certain market conditions, the Fund may invest in BDCs or Underlying Funds that are subject to income risk. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
F/m Accumulator BDC Fund | Industry Sector Risk  
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Risk [Text Block]
Industry Sector Risk. From time to time, the Fund may invest a significant portion of its assets in companies in one or more related industries or sectors, which would make the Fund more vulnerable to adverse developments affecting those industries or sectors. BDCs, as financial services companies, may be affected by the availability and cost of capital; changes in interest rates; insurance claims activity; industry consolidation; reduced profitability from limitations on loans; proprietary trading; interest rates and fees charged as a result of extensive government regulations; and general market conditions.

 

oFinancial Sector Risk. Financial services companies are subject to extensive government regulation and, as a result, their profitability may be affected by new regulations or regulatory interpretations. Changes in interest rates can have a disproportionate effect on the financial sector and financial services companies whose securities the Fund may purchase may themselves have concentrated portfolios, which makes them vulnerable to economic conditions that affect that sector. Financial services companies have also been affected by increased competition, which could adversely affect the profitability or viability of such companies.
F/m Accumulator BDC Fund | Inflation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Inflation Risk. Under certain market conditions, the Fund may invest in a BDC or Underlying Fund that is subject to inflation risk. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets may decline.
F/m Accumulator BDC Fund | Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Interest-Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt instruments tend to fall, and if interest rates fall, the values of debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates, which may negatively affect the value of debt instruments held by the Fund and have a negative impact on the Fund’s performance and NAV. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. The historically low-interest rate environment in recent years heightens the risks associated with rising interest rates.
F/m Accumulator BDC Fund | Investment Restriction Risk  
Prospectus [Line Items]  
Risk [Text Block]
Investment Restriction Risk. The Fund is subject to the conditions set forth in certain provisions of the Investment Company Act and SEC regulations thereunder that limit the amount that the Fund and its affiliates, in the aggregate, can invest in the outstanding voting securities of an unaffiliated investment company or business development company. The Fund and its affiliates may not actively acquire “control” of an investment company or business development company, which is presumed once ownership of an investment company’s outstanding voting securities exceeds 25%. Also, to comply with provisions of the Investment Company Act of 1940 and regulations thereunder, the Adviser may be required to vote shares of an investment company or business development company in the same general proportion as shares held by other shareholders of the investment company or business development company.
F/m Accumulator BDC Fund | Issuer Risk  
Prospectus [Line Items]  
Risk [Text Block]
Issuer Risk. The performance of the Fund’s investment in BDCs and Underlying Funds depends on the performance of individual securities or other assets to which the BDC or Underlying Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
F/m Accumulator BDC Fund | Liquidity Risk  
Prospectus [Line Items]  
Risk [Text Block]
Liquidity Risk. Certain securities held by a BDC or Underlying Fund may be difficult (or impossible) to sell at the time and at the price the Adviser would like. As a result, a BDC or Underlying Fund may have to hold these securities longer than it would like and may forego other investment opportunities. There is the possibility that a BDC or Underlying Fund may lose money or be prevented from realizing capital gains if it cannot sell a security at a particular time and price.
F/m Accumulator BDC Fund | Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Management Risk. The Fund is subject to management risk, which is the risk that the Adviser’s analysis of economic conditions and expectations regarding interest rate changes may fail to produce the intended results. In other words, the individual investments of the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.
F/m Accumulator BDC Fund | Market Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Risk. Economies and financial markets throughout the world are becoming increasingly interconnected, which increases the likelihood that events or conditions in one country or region will adversely impact markets or issuers in other countries or regions. The value of the Fund and/or the BDC’s or Underlying Fund’s investments may be negatively affected by adverse changes in overall economic or market conditions, such as the level of economic activity and productivity, unemployment and labor force participation rates, inflation or deflation (and expectations for inflation or deflation), interest rates, demand and supply for particular products or resources including labor, and debt levels and credit ratings, among other factors. Such adverse conditions may contribute to an overall economic contraction across entire economies or markets, which may negatively impact the profitability of issuers operating in those economies or markets. The Fund and the BDCs and Underlying Funds are subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. The Fund’s, the BDCs’, and the Underlying Funds’ NAVs and market prices may fluctuate significantly in response to these and other factors including economic, political, or financial events, public health crises (such as epidemics or pandemics), or other disruptive events (whether real, expected or perceived) in the U.S. and global markets. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. As a result, an investor could lose money over short or long periods of time.
F/m Accumulator BDC Fund | Market Price Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Price Risk. Fund Shares are listed for trading on an exchange and are bought and sold in the secondary market at market prices. The market prices of Shares will fluctuate, in some cases materially, in response to changes in the NAV and supply and demand for Shares. As a result, the trading prices of Shares may deviate significantly from the NAV during periods of market volatility. The Adviser cannot predict whether Shares will trade above, below or at their NAV. Given the fact that Shares can be created and redeemed in Creation Units (defined below), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained in the long term. If market makers exit the business or are unable to continue making markets in Fund Shares, Shares may trade at a discount to NAV like closed-end fund shares and may even face delisting (that is, investors would no longer be able to trade Shares in the secondary market). Further, while the creation/redemption feature is designed to make it likely that Shares normally will trade close to the value of the Fund’s holdings, disruptions to creations and redemptions, including disruptions at market makers, APs or market participants, or during periods of significant market volatility, may result in market prices that differ significantly from the value of the Fund’s holdings. Although market makers will generally take advantage of differences between the NAV and the market price of Fund Shares through arbitrage opportunities, there is no guarantee that they will do so. In addition, the securities held by the Fund may be traded in markets that close at a different time than the exchange on which the Fund’s Shares trade. Liquidity in those securities may be reduced after the applicable closing times. Accordingly, during the time when the exchange is open but after the applicable market closing, fixing or settlement times, bid-ask spreads and the resulting premium or discount to the Shares’ NAV are likely to widen. Further, secondary markets may be subject to irregular trading activity, wide bid-ask spreads and extended trade settlement periods, which could cause a material decline in the Fund’s NAV. The Fund’s investment results are measured based upon the daily NAV of the Fund. Investors purchasing and selling Shares in the secondary market may not experience investment results consistent with those experienced by those APs creating and redeeming Shares directly with the Fund.
F/m Accumulator BDC Fund | Market Trading Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund Shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund Shares. Any of these factors, among others, may lead to the Fund’s Shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund Shares at a time when the market price is at a premium to NAV or sell Fund Shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund Shares.
F/m Accumulator BDC Fund | New Fund Risk  
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Risk [Text Block]
New Fund Risk. The Fund is a newly-organized management investment company with a limited operating history. In addition, there can be no assurance that the Fund will grow to, or maintain, an economically viable size, in which case the Board of Directors (the “Board”) of The RBB Fund, Inc. (the “Company”) may determine to liquidate the Fund.
F/m Accumulator BDC Fund | Operational Risk  
Prospectus [Line Items]  
Risk [Text Block]
Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties, or other third parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
F/m Accumulator BDC Fund | Options Risk  
Prospectus [Line Items]  
Risk [Text Block]
Options Risk. If the Fund purchases a call option, it receives, in return for the premium it pays, the right to buy from the writer of the option the underlying security at a specified price at any time before the option expires. The Fund purchases call options in anticipation of an increase in the market value of securities that it intends ultimately to buy. During the life of the call option, the Fund is able to buy the underlying security at the exercise price regardless of any increase in the market price of the underlying security. In order for a call option to result in a gain, the market price of the underlying security must exceed the sum of the exercise price, the premium paid, and transaction costs.
F/m Accumulator BDC Fund | Premium/Discount Risk  
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Risk [Text Block]
Premium/Discount Risk. The market price of the Fund’s Shares will generally fluctuate in accordance with changes in the Fund’s NAV as well as the relative supply of and demand for Shares on the Exchange. The Adviser cannot predict whether Shares will trade below, at, or above their NAV because the Shares trade on the Exchange at market prices and not at NAV. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for Shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that Shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAV), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained. During stressed market conditions, the market for the Fund’s Shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying holdings, which could in turn lead to differences between the market price of the Fund’s Shares and their NAV and the bid/ask spread on the Fund’s Shares may widen.
F/m Accumulator BDC Fund | Prepayment and Extension Risk  
Prospectus [Line Items]  
Risk [Text Block]
Prepayment and Extension Risk. When interest rates fall, issuers of high interest debt obligations may pay off the debts earlier than expected (prepayment risk), and the Fund may have to reinvest the proceeds at lower yields. When interest rates rise, issuers of lower interest debt obligations may pay off the debts later than expected (extension risk), thus keeping the Fund’s assets tied up in lower interest debt obligations. Ultimately, any unexpected behavior in interest rates could increase the volatility of the Fund’s Share price and yield and could hurt Fund performance. Prepayments could also create capital gains tax liability in some instances.
F/m Accumulator BDC Fund | Pricing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Pricing Risk. If market conditions make it difficult to value some investments, the Fund may value these investments using more subjective methods, such as fair value pricing. In such cases, the value determined for an investment could be different from the value realized upon such investment’s sale. As a result, you could pay more than the market value when buying Fund Shares or receive less than the market value when selling Fund Shares.
F/m Accumulator BDC Fund | Rating Agencies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Rating Agencies Risk. Ratings are not an absolute standard of quality, but rather general indicators that reflect only the view of the originating rating agencies from which an explanation of the significance of such ratings may be obtained. There is no assurance that a particular rating will continue for any given period of time or that any such rating will not be revised downward or withdrawn entirely if, in the judgment of the agency establishing the rating, circumstances so warrant. A downward revision or withdrawal of such ratings, or either of them, may have an effect on the liquidity or market price of the securities in which a BDC or Underlying Fund invests.
F/m Accumulator BDC Fund | Regulatory Risk  
Prospectus [Line Items]  
Risk [Text Block]
Regulatory Risk. Changes in the laws or regulations of the United States, including any changes to applicable tax laws and regulations, could impair the ability of the Fund to achieve its investment objective and could increase the operating expenses of the Fund. The Adviser is operating under an exemption from the U.S. Commodity Exchange Act and the rules of the Commodity Futures Trading Commission (the “CFTC”); however, it may register as a commodity pool operator at a future date, at which time it would be subject to CFTC regulation with respect to the Fund. To the extent that the Adviser is required to register with the CFTC, the CFTC has adopted rules regarding the disclosure, reporting and recordkeeping requirements that will apply with respect to applicable funds. Generally, these rules allow for substituted compliance with CFTC disclosure and shareholder reporting requirements, based on the Adviser’s compliance with comparable SEC requirements. This means that for most of the CFTC’s disclosure and shareholder reporting applicable to the Adviser as a fund’s commodity pool operator, the Adviser’s compliance with SEC disclosure and shareholder reporting would be deemed to fulfill the Adviser’s CFTC obligations. However, if a fund is regulated by the CFTC, such fund may incur additional compliance and other expenses.
F/m Accumulator BDC Fund | Reinvestment Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reinvestment Risk. Reinvestment risk is the risk that the Fund’s portfolio will decline if and when the Fund reinvests the proceeds from the disposition of its portfolio securities at market interest rates that are below the portfolio’s current earnings rate. A decline in income could negatively affect the market price of the Shares.
F/m Accumulator BDC Fund | Reverse Repurchase Agreements Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reverse Repurchase Agreements Risk. Reverse repurchase agreements are a form of secured borrowing and subject the Fund to the risks associated with leverage, including exposure to potential gains and losses in excess of the amount invested, resulting in an increase in the speculative character of the Fund’s outstanding Shares. Reverse repurchase agreements involve the risk that the investment return earned by the Fund (from the investment of the proceeds) will be less than the interest expense of the transaction, that the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities, and that the other party may fail to return the securities in a timely manner or at all.
F/m Accumulator BDC Fund | Risk of Investing in the U.S.  
Prospectus [Line Items]  
Risk [Text Block]
Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
F/m Accumulator BDC Fund | Securities Lending Risk  
Prospectus [Line Items]  
Risk [Text Block]
Securities Lending Risk. The Fund may engage in securities lending (i.e., lend portfolio securities to institutions, such as certain broker-dealers). Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investment made with cash collateral. These events could also trigger adverse tax consequences for the Fund. The Fund could also experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.
F/m Accumulator BDC Fund | Swaps Risk  
Prospectus [Line Items]  
Risk [Text Block]
Swaps Risk. The Fund will invest in swap agreements, which may be less liquid than other types of investments. The illiquidity of swap agreements could have a negative effect on the Fund’s ability to achieve its investment objective and may result in losses to Fund shareholders. In stressed market conditions, the liquidity of the Fund’s Shares may begin to mirror those of the underlying portfolio holdings, which can be significantly less liquid than the Fund’s Shares.
F/m Accumulator BDC Fund | Tax Risk  
Prospectus [Line Items]  
Risk [Text Block]
Tax Risk. Because the Fund is expected to invest in the Underlying Funds, distributions of short-term capital gains by an Underlying Fund will be recognized as ordinary income by the Fund and would not be offset by the Fund’s capital loss carryforwards, if any. Capital loss carryforwards of an Underlying Fund, if any, will not be available to offset net capital gains of the Fund. Further, the Fund’s realized losses on sales of shares of an Underlying Fund may be indefinitely or permanently deferred as “wash sales” to the extent it re-acquires shares of the same Underlying Fund within the 61-day period beginning 30 days prior to the disposition date. Additionally, the Fund intends to qualify annually to be treated as a RIC under the Code. To qualify as a RIC under the Code, the Fund must invest in assets which produce the types of income specified in the Code and the Treasury regulations (“Qualifying Income”). Whether the income from certain derivatives, swaps, commodity-linked derivatives and other commodity/natural resource-related securities is Qualifying Income is unclear. The Internal Revenue Service (“IRS”) has issued a ruling that income realized from certain types of commodity-linked derivatives would not be Qualifying Income. If the Fund’s income is determined to not be Qualifying Income, it may cause the Fund to fail to qualify as a RIC under the Code.
F/m Accumulator BDC Fund | Underlying Funds Risk  
Prospectus [Line Items]  
Risk [Text Block]
Underlying Funds Risk. The Fund’s investment in shares of Underlying Funds subjects it to the risks of owning the securities of the Underlying Fund, as well as the same structural risks faced by an investor purchasing shares of the Underlying Fund, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses. Since the Fund invests in the Underlying Funds, the Fund’s investment performance and risks are likely to be directly related to those of the Underlying Funds. The Fund’s NAV will change with changes in the value of the Underlying Funds and other assets that the Fund holds. The shares of an Underlying Fund may trade at a premium or discount to the Underlying Fund’s NAV. Investors in the Fund will indirectly bear the expenses charged by the Underlying Funds, and an investment in the Fund may entail more expenses than a direct investment in the Underlying Funds.
F/m Accumulator BDC Fund | U.S. Government Obligations Risk  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.
F/m Accumulator BDC Fund | Valuation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Valuation Risk. The prices provided by the Fund’s pricing services or independent dealers or the fair value determinations made by the valuation committee of the Adviser may be different from the prices used by other funds or from the prices at which securities are actually bought and sold. The prices of certain securities provided by pricing services may be subject to frequent and significant change, and will vary depending on the information that is available.
F/m Accumulator BDC Fund | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] As a result, you may lose money on your investment in the Fund, and there can be no assurance that the Fund will achieve its investment objective.
F/m Accumulator BDC Fund | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Non-Diversification Risk. The Fund is classified as “non-diversified” under the Investment Company Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Code. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers. Additionally, to the extent that the Fund invests a significant percentage of its assets in a single asset class or industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified. Because the Fund expects to invest a significant portion of its assets in the financial sector, it may be more susceptible to adverse economic or regulatory occurrences affecting this sector, such as changes in interest rates, loan concentration, government regulation and competition.
F/m Accumulator Mortgage REIT Fund | Active Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Active Management Risk. The Fund is actively managed using proprietary investment strategies and processes. There can be no guarantee that these strategies and processes will be successful or that the Fund will achieve its investment objective.
F/m Accumulator Mortgage REIT Fund | Affiliated Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
Affiliated Fund Risk. Affiliated fund risk is the risk that the Adviser may select Underlying Funds and/or investments for the Fund based on its own financial interests or other business considerations rather than the Fund’s interests. The Adviser may be subject to potential conflicts of interest in selecting the Underlying Funds because affiliated Underlying Funds pay an advisory fee to the Adviser based on their assets, the fees paid to the Adviser by some affiliated Underlying Funds may be higher than those paid by other Underlying Funds or the Underlying Funds may be in need of assets to enhance their appeal to other investors, liquidity and trading and/or to enable them to carry out their investment strategies. However, the Adviser is a fiduciary to the Fund and is legally obligated to act in the Fund’s best interest when selecting Underlying Funds.
F/m Accumulator Mortgage REIT Fund | Asset Class Risk  
Prospectus [Line Items]  
Risk [Text Block]
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market, or other asset classes.
F/m Accumulator Mortgage REIT Fund | Call Risk  
Prospectus [Line Items]  
Risk [Text Block]
Call Risk. During periods of falling interest rates, an issuer of a callable bond held by an Underlying Fund may “call” or repay the security before its stated maturity, and the Underlying Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund’s performance, or in securities with greater risks or with other less favorable features.
F/m Accumulator Mortgage REIT Fund | Cash or Cash Equivalents Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cash or Cash Equivalents Risk. At any time, the Fund may have significant investments in cash or cash equivalents. When a substantial portion of a portfolio is held in cash or cash equivalents, there is the risk that the value of the cash account, including interest, will not keep pace with inflation, thus reducing purchasing power over time. Additionally, in rising markets, holding cash or cash equivalents may adversely affect the Fund’s performance and the Fund may not achieve its investment objectives.
F/m Accumulator Mortgage REIT Fund | Concentration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in a particular issue, issuer or issuers, country, market segment, or asset class.
F/m Accumulator Mortgage REIT Fund | Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Credit Risk. The value of your investment in the Fund may change in response to changes in the credit ratings of the Fund’s portfolio securities, including with respect to Underlying Funds. Generally, investment risk and price volatility increase as a security’s credit rating declines. The financial condition of an issuer of a fixed income security held by such Fund or an Underlying Fund may cause it to default or become unable to pay interest or principal due on the security.
F/m Accumulator Mortgage REIT Fund | Cyber Security Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to the Fund’s assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent the Fund’s investors from purchasing, redeeming or exchanging Shares or receiving distributions. While the Fund and the Adviser have established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Further, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, or issuers of securities in which the Fund invests. The Fund and the Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or the Adviser. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders. Issuers of securities in which the Fund invests are also subject to cyber security risks, and the value of these securities could decline if the issuers experience cyberattacks or other cyber-failures.
F/m Accumulator Mortgage REIT Fund | Derivatives Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk. Derivatives and other similar instruments (referred to collectively as “derivatives”) are financial instruments whose values are based on the value of one or more reference assets or indicators, such as a security, currency, interest rate, or index. The Fund’s use of derivatives involves risks different from, and possibly greater than, the risks associated with investing directly in securities and other more traditional investments. Moreover, although the value of a derivative is based on an underlying asset or indicator, a derivative typically does not carry the same rights as would be the case if the Fund invested directly in the underlying securities, currencies or other assets.

 

Derivatives are subject to a number of risks, such as potential changes in value in response to market developments or, in the case of “over-the-counter” derivatives, as a result of a counterparty’s credit quality and the risk that a derivative transaction may not have the effect the Adviser anticipated. Derivatives also involve the risk of mispricing or improper valuation and the risk that changes in the value of a derivative may not achieve the desired correlation with the underlying asset or indicator. Derivative transactions can create investment leverage and may be highly volatile, and the Fund could lose more than the amount it invests. The use of derivatives may increase the amount and affect the timing and character of taxes payable by shareholders of the Fund.

 

Many derivative transactions are entered into “over-the-counter” without a central clearinghouse; as a result, the value of such a derivative transaction will depend on, among other factors, the ability and the willingness of the Fund’s counterparty to perform its obligations under the transaction. If a counterparty were to default on its obligations, the Fund’s contractual remedies against such counterparty may be subject to bankruptcy and insolvency laws, which could affect the Fund’s rights as a creditor (e.g., the Fund may not receive the net amount of payments that it is contractually entitled to receive). Counterparty risk also refers to the related risks of having concentrated exposure to such a counterparty. A liquid secondary market may not always exist for the Fund’s derivative positions at any time, and the Fund may not be able to initiate or liquidate a swap position at an advantageous time or price, which may result in significant losses. The Fund may also face the risk that it may not be able to meet margin and payment requirements and maintain a derivatives position.

 

Derivatives are also subject to operational and legal risks. Operational risk generally refers to risk related to potential operational issues, including documentation issues, settlement issues, system failures, inadequate controls, and human errors. Legal risk generally refers to insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract.

F/m Accumulator Mortgage REIT Fund | Derivatives Counterparty Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Counterparty Risk. A loss may be sustained as a result of the failure of another party to a contract (usually referred to as a “counterparty”) to make required payments, fulfill its contractual obligations or otherwise comply with a contract’s terms because of the financial condition of the counterparty (i.e., financial difficulties or insolvency), market activities and developments, the counterparty being unable or unwilling to perform under the contract or other reasons. In a swap agreement, the Fund bears the risk of loss of the amount expected to be received under the agreement in the event of the default or bankruptcy of a counterparty. These risks are heightened and may materially impact the Fund’s ability to achieve its investment objective given that the Fund may enter into swap agreements with one or a limited number of counterparties. The Fund’s use of one or a limited number of counterparties increases the Fund’s exposure to counterparty credit risk. Credit risk refers to the possibility that the counterparty will be unable and/or unwilling to honor its obligations and/or default completely on the derivative transaction. Swap agreements also may be considered to be illiquid. Further, there is a risk that no suitable counterparties are willing to enter into, or continue to enter into, transactions with the Fund and, as a result, the Fund may not be able to achieve its investment objective.
F/m Accumulator Mortgage REIT Fund | Duration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Duration Risk. Duration is a measure of the price sensitivity of a debt security or portfolio to interest rate changes. Duration risk is the risk that longer-duration debt securities will be more volatile and thus more likely to decline in price, and to a greater extent, in a rising interest rate environment than shorter-duration debt securities.
F/m Accumulator Mortgage REIT Fund | Equity Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Equity Securities Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the markets in which the issuers of securities held by the Fund participate, or factors relating to specific issuers in which the Fund invests. Equity securities are subordinated to preferred securities and debt in a company’s capital structure with respect to priority to a share of corporate income, and therefore will be subject to greater dividend risk than preferred securities or debt instruments. In addition, while broad market measures of equity securities have historically generated higher average returns than fixed income securities, equity securities have generally also experienced significantly more volatility in those returns.
F/m Accumulator Mortgage REIT Fund | ETF Risk  
Prospectus [Line Items]  
Risk [Text Block]
ETF Risk. The Fund is an ETF, and, as a result of an ETF’s structure, it is exposed to the following risks:

 

oAuthorized Participants, Market Makers and Liquidity Providers Concentration Risk. Only an authorized participant (“AP”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that are institutional investors and may act as APs. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent either of the following events occur, there may be significantly diminished trading in Fund Shares, Fund Shares may trade at a material discount to net asset value (“NAV”), and Fund Shares may possibly face delisting: (i) if APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services, or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform their functions. These events, among others, may lead to Fund Shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than the NAV when you buy Shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those Shares in the secondary market. A diminished market for an ETF’s shares substantially increases the risk that a shareholder may pay considerably more or receive significantly less than the underlying value of the ETF shares bought or sold. In periods of market volatility, APs, market makers and/or liquidity providers may be less willing to transact in Fund Shares.

 

oSecondary Market Trading Risk. Although Shares are intended to be listed on a national securities exchange, The Nasdaq Stock Market LLC (the “Exchange”), and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Shares on the Exchange may be halted. During periods of market stress, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines.

 

oShares May Trade at Prices Other Than NAV Risk. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Shares trade on a stock exchange at prices at, above, or below the Fund’s most recent NAV. The Fund’s NAV is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings. The trading price of the Shares fluctuates continuously throughout trading hours on the exchange, based on both the relative market supply of, and demand for, the Shares and the underlying value of the Fund’s portfolio holdings. As a result, the trading prices of the Shares may deviate from the Fund’s NAV. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. Any of these factors, among others, may lead to the Shares trading at a premium or discount to NAV.

 

To the extent the Fund invests in Underlying Funds, which are also ETFs, the Fund will be further exposed to the above ETF risks.

F/m Accumulator Mortgage REIT Fund | Futures Risk  
Prospectus [Line Items]  
Risk [Text Block]
Futures Risk. Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.
F/m Accumulator Mortgage REIT Fund | High Portfolio Turnover Risk  
Prospectus [Line Items]  
Risk [Text Block]
High Portfolio Turnover Risk. Active and frequent trading of the Fund’s portfolio securities may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.
F/m Accumulator Mortgage REIT Fund | Income Risk  
Prospectus [Line Items]  
Risk [Text Block]
Income Risk. Under certain market conditions, the Fund may invest in Underlying Funds that are subject to income risk. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
F/m Accumulator Mortgage REIT Fund | Inflation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Inflation Risk. Under certain market conditions, the Fund may invest in an Underlying Fund that is subject to inflation risk. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets may decline.
F/m Accumulator Mortgage REIT Fund | Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Interest-Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt instruments tend to fall, and if interest rates fall, the values of debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates, which may negatively affect the value of debt instruments held by the Fund and have a negative impact on the Fund’s performance and NAV. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. The historically low-interest rate environment in recent years heightens the risks associated with rising interest rates.
F/m Accumulator Mortgage REIT Fund | Investment Restriction Risk  
Prospectus [Line Items]  
Risk [Text Block]
Investment Restriction Risk. The Fund is subject to the conditions set forth in certain provisions of the 1940 Act and SEC regulations thereunder that limit the amount that the Fund and its affiliates, in the aggregate, can invest in the outstanding voting securities of an unaffiliated investment company or business development company. The Fund and its affiliates may not actively acquire “control” of an investment company or business development company, which is presumed once ownership of an investment company’s outstanding voting securities exceeds 25%. Also, to comply with provisions of the 1940 Act and regulations thereunder, the Adviser may be required to vote shares of an investment company or business development company in the same general proportion as shares held by other shareholders of the investment company or business development company.
F/m Accumulator Mortgage REIT Fund | Issuer Risk  
Prospectus [Line Items]  
Risk [Text Block]
Issuer Risk. The performance of the Fund’s investment in Underlying Funds depends on the performance of individual securities or other assets to which the Underlying Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
F/m Accumulator Mortgage REIT Fund | Liquidity Risk  
Prospectus [Line Items]  
Risk [Text Block]
Liquidity Risk. Certain securities held by an Underlying Fund may be difficult (or impossible) to sell at the time and at the price the Adviser would like. As a result, an Underlying Fund may have to hold these securities longer than it would like and may forego other investment opportunities. There is the possibility that an Underlying Fund may lose money or be prevented from realizing capital gains if it cannot sell a security at a particular time and price.
F/m Accumulator Mortgage REIT Fund | Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Management Risk. The Fund is subject to management risk, which is the risk that the Adviser’s analysis of economic conditions and expectations regarding interest rate changes may fail to produce the intended results. In other words, the individual investments of the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.
F/m Accumulator Mortgage REIT Fund | Market Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Risk. Economies and financial markets throughout the world are becoming increasingly interconnected, which increases the likelihood that events or conditions in one country or region will adversely impact markets or issuers in other countries or regions. The value of the Fund and/or the Underlying Fund’s investments may be negatively affected by adverse changes in overall economic or market conditions, such as the level of economic activity and productivity, unemployment and labor force participation rates, inflation or deflation (and expectations for inflation or deflation), interest rates, demand and supply for particular products or resources including labor, and debt levels and credit ratings, among other factors. Such adverse conditions may contribute to an overall economic contraction across entire economies or markets, which may negatively impact the profitability of issuers operating in those economies or markets. The Fund and the Underlying Funds are subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. The Fund’s and the Underlying Funds’ NAVs and market prices may fluctuate significantly in response to these and other factors including economic, political, or financial events, public health crises (such as epidemics or pandemics), or other disruptive events (whether real, expected or perceived) in the U.S. and global markets. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. As a result, an investor could lose money over short or long periods of time.
F/m Accumulator Mortgage REIT Fund | Market Price Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Price Risk. Fund Shares are listed for trading on an exchange and are bought and sold in the secondary market at market prices. The market prices of Shares will fluctuate, in some cases materially, in response to changes in the NAV and supply and demand for Shares. As a result, the trading prices of Shares may deviate significantly from the NAV during periods of market volatility. The Adviser cannot predict whether Shares will trade above, below or at their NAV. Given the fact that Shares can be created and redeemed in Creation Units (defined below), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained in the long term. If market makers exit the business or are unable to continue making markets in Fund Shares, Shares may trade at a discount to NAV like closed-end fund shares and may even face delisting (that is, investors would no longer be able to trade Shares in the secondary market). Further, while the creation/redemption feature is designed to make it likely that Shares normally will trade close to the value of the Fund’s holdings, disruptions to creations and redemptions, including disruptions at market makers, APs or market participants, or during periods of significant market volatility, may result in market prices that differ significantly from the value of the Fund’s holdings. Although market makers will generally take advantage of differences between the NAV and the market price of Fund Shares through arbitrage opportunities, there is no guarantee that they will do so. In addition, the securities held by the Fund may be traded in markets that close at a different time than the exchange on which the Fund’s Shares trade. Liquidity in those securities may be reduced after the applicable closing times. Accordingly, during the time when the exchange is open but after the applicable market closing, fixing or settlement times, bid-ask spreads and the resulting premium or discount to the Shares’ NAV are likely to widen. Further, secondary markets may be subject to irregular trading activity, wide bid-ask spreads and extended trade settlement periods, which could cause a material decline in the Fund’s NAV. The Fund’s investment results are measured based upon the daily NAV of the Fund. Investors purchasing and selling Shares in the secondary market may not experience investment results consistent with those experienced by those APs creating and redeeming Shares directly with the Fund.
F/m Accumulator Mortgage REIT Fund | Market Trading Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund Shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund Shares. Any of these factors, among others, may lead to the Fund’s Shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund Shares at a time when the market price is at a premium to NAV or sell Fund Shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund Shares.
F/m Accumulator Mortgage REIT Fund | New Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
New Fund Risk. The Fund is a newly-organized management investment company with a limited operating history. In addition, there can be no assurance that the Fund will grow to, or maintain, an economically viable size, in which case the Board of Directors (the “Board”) of The RBB Fund, Inc. (the “Company”) may determine to liquidate the Fund.
F/m Accumulator Mortgage REIT Fund | Operational Risk  
Prospectus [Line Items]  
Risk [Text Block]
Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties, or other third parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
F/m Accumulator Mortgage REIT Fund | Options Risk  
Prospectus [Line Items]  
Risk [Text Block]
Options Risk. If the Fund purchases a call option, it receives, in return for the premium it pays, the right to buy from the writer of the option the underlying security at a specified price at any time before the option expires. The Fund purchases call options in anticipation of an increase in the market value of securities that it intends ultimately to buy. During the life of the call option, the Fund is able to buy the underlying security at the exercise price regardless of any increase in the market price of the underlying security. In order for a call option to result in a gain, the market price of the underlying security must exceed the sum of the exercise price, the premium paid, and transaction costs.
F/m Accumulator Mortgage REIT Fund | Premium/Discount Risk  
Prospectus [Line Items]  
Risk [Text Block]
Premium/Discount Risk. The market price of the Fund’s Shares will generally fluctuate in accordance with changes in the Fund’s NAV as well as the relative supply of and demand for Shares on the Exchange. The Adviser cannot predict whether Shares will trade below, at, or above their NAV because the Shares trade on the Exchange at market prices and not at NAV. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for Shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that Shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAV), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained. During stressed market conditions, the market for the Fund’s Shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying holdings, which could in turn lead to differences between the market price of the Fund’s Shares and their NAV and the bid/ask spread on the Fund’s Shares may widen.
F/m Accumulator Mortgage REIT Fund | Prepayment and Extension Risk  
Prospectus [Line Items]  
Risk [Text Block]
Prepayment and Extension Risk. When interest rates fall, issuers of high interest debt obligations may pay off the debts earlier than expected (prepayment risk), and the Fund may have to reinvest the proceeds at lower yields. When interest rates rise, issuers of lower interest debt obligations may pay off the debts later than expected (extension risk), thus keeping the Fund’s assets tied up in lower interest debt obligations. Ultimately, any unexpected behavior in interest rates could increase the volatility of the Fund’s Share price and yield and could hurt Fund performance. Prepayments could also create capital gains tax liability in some instances.
F/m Accumulator Mortgage REIT Fund | Pricing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Pricing Risk. If market conditions make it difficult to value some investments, the Fund may value these investments using more subjective methods, such as fair value pricing. In such cases, the value determined for an investment could be different from the value realized upon such investment’s sale. As a result, you could pay more than the market value when buying Fund Shares or receive less than the market value when selling Fund Shares.
F/m Accumulator Mortgage REIT Fund | Rating Agencies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Rating Agencies Risk. Ratings are not an absolute standard of quality, but rather general indicators that reflect only the view of the originating rating agencies from which an explanation of the significance of such ratings may be obtained. There is no assurance that a particular rating will continue for any given period of time or that any such rating will not be revised downward or withdrawn entirely if, in the judgment of the agency establishing the rating, circumstances so warrant. A downward revision or withdrawal of such ratings, or either of them, may have an effect on the liquidity or market price of the securities in which an Underlying Fund invests.
F/m Accumulator Mortgage REIT Fund | Regulatory Risk  
Prospectus [Line Items]  
Risk [Text Block]
Regulatory Risk. Changes in the laws or regulations of the United States, including any changes to applicable tax laws and regulations, could impair the ability of the Fund to achieve its investment objective and could increase the operating expenses of the Fund. The Adviser is operating under an exemption from the U.S. Commodity Exchange Act and the rules of the Commodity Futures Trading Commission (the “CFTC”); however, it may register as a commodity pool operator at a future date, at which time it would be subject to CFTC regulation with respect to the Fund. To the extent that the Adviser is required to register with the CFTC, the CFTC has adopted rules regarding the disclosure, reporting and recordkeeping requirements that will apply with respect to applicable funds. Generally, these rules allow for substituted compliance with CFTC disclosure and shareholder reporting requirements, based on the Adviser’s compliance with comparable SEC requirements. This means that for most of the CFTC’s disclosure and shareholder reporting applicable to the Adviser as a fund’s commodity pool operator, the Adviser’s compliance with SEC disclosure and shareholder reporting would be deemed to fulfill the Adviser’s CFTC obligations. However, if a fund is regulated by the CFTC, such fund may incur additional compliance and other expenses.
F/m Accumulator Mortgage REIT Fund | Reinvestment Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reinvestment Risk. Reinvestment risk is the risk that the Fund’s portfolio will decline if and when the Fund reinvests the proceeds from the disposition of its portfolio securities at market interest rates that are below the portfolio’s current earnings rate. A decline in income could negatively affect the market price of the Shares.
F/m Accumulator Mortgage REIT Fund | Reverse Repurchase Agreements Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reverse Repurchase Agreements Risk. Reverse repurchase agreements are a form of secured borrowing and subject the Fund to the risks associated with leverage, including exposure to potential gains and losses in excess of the amount invested, resulting in an increase in the speculative character of the Fund’s outstanding Shares. Reverse repurchase agreements involve the risk that the investment return earned by the Fund (from the investment of the proceeds) will be less than the interest expense of the transaction, that the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities, and that the other party may fail to return the securities in a timely manner or at all.
F/m Accumulator Mortgage REIT Fund | Risk of Investing in the U.S.  
Prospectus [Line Items]  
Risk [Text Block]
Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
F/m Accumulator Mortgage REIT Fund | Securities Lending Risk  
Prospectus [Line Items]  
Risk [Text Block]
Securities Lending Risk. The Fund may engage in securities lending (i.e., lend portfolio securities to institutions, such as certain broker-dealers). Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investment made with cash collateral. These events could also trigger adverse tax consequences for the Fund. The Fund could also experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.
F/m Accumulator Mortgage REIT Fund | Swaps Risk  
Prospectus [Line Items]  
Risk [Text Block]
Swaps Risk. The Fund will invest in swap agreements, which may be less liquid than other types of investments. The illiquidity of swap agreements could have a negative effect on the Fund’s ability to achieve its investment objective and may result in losses to Fund shareholders. In stressed market conditions, the liquidity of the Fund’s Shares may begin to mirror those of the underlying portfolio holdings, which can be significantly less liquid than the Fund’s Shares.
F/m Accumulator Mortgage REIT Fund | Tax Risk  
Prospectus [Line Items]  
Risk [Text Block]
Tax Risk. Because the Fund is expected to invest in the Underlying Funds, distributions of short-term capital gains by an Underlying Fund will be recognized as ordinary income by the Fund and would not be offset by the Fund’s capital loss carryforwards, if any. Capital loss carryforwards of an Underlying Fund, if any, will not be available to offset net capital gains of the Fund. Further, the Fund’s realized losses on sales of shares of an Underlying Fund may be indefinitely or permanently deferred as “wash sales” to the extent it re-acquires shares of the same Underlying Fund within the 61-day period beginning 30 days prior to the disposition date.
F/m Accumulator Mortgage REIT Fund | Underlying Funds Risk  
Prospectus [Line Items]  
Risk [Text Block]
Underlying Funds Risk. The Fund’s investment in shares of Underlying Funds subjects it to the risks of owning the securities of the Underlying Fund, as well as the same structural risks faced by an investor purchasing shares of the Underlying Fund, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses. Since the Fund invests in the Underlying Funds, the Fund’s investment performance and risks are likely to be directly related to those of the Underlying Funds. The Fund’s NAV will change with changes in the value of the Underlying Funds and other assets that the Fund holds. The shares of an Underlying Fund may trade at a premium or discount to the Underlying Fund’s NAV. Investors in the Fund will indirectly bear the expenses charged by the Underlying Funds, and an investment in the Fund may entail more expenses than a direct investment in the Underlying Funds.
F/m Accumulator Mortgage REIT Fund | U.S. Government Obligations Risk  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.
F/m Accumulator Mortgage REIT Fund | Valuation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Valuation Risk. The prices provided by the Fund’s pricing services or independent dealers or the fair value determinations made by the valuation committee of the Adviser may be different from the prices used by other funds or from the prices at which securities are actually bought and sold. The prices of certain securities provided by pricing services may be subject to frequent and significant change, and will vary depending on the information that is available.
F/m Accumulator Mortgage REIT Fund | Large Capitalization Company Risk  
Prospectus [Line Items]  
Risk [Text Block]
Large Capitalization Company Risk. Large capitalization (“Large-cap”) companies are generally more mature and the securities issued by these companies may not be able to reach the same levels of growth as the securities issued by small- or middle-capitalization companies.
F/m Accumulator Mortgage REIT Fund | Market Capitalization Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Capitalization Risk. Securities issued by companies of different market capitalizations tend to go in and out of favor based on market and economic conditions. During a period when securities of a particular market capitalization fall behind other types of investments, the Fund’s performance could be impacted.
F/m Accumulator Mortgage REIT Fund | Mortgage-Backed Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Mortgage-Backed Securities Risk. The value of mortgage-backed securities may be affected by, among other things, changes or perceived changes in: interest rates; factors concerning the interests in and structure of the issuer or the originator of the mortgages; the creditworthiness of the entities that provide any supporting letters of credit, surety bonds or other credit enhancements; or the market’s assessment of the quality of underlying assets. Payment of principal and interest on some mortgage-backed securities (but not the market value of the securities themselves) may be guaranteed by the full faith and credit of a particular U.S. Government agency, authority, enterprise or instrumentality, and some, but not all, are also insured or guaranteed by the U.S. Government. Mortgage-backed securities issued by non-governmental issuers (such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers) may entail greater risk than obligations guaranteed by the U.S. Government. Mortgage-backed securities are subject to liquidity risk and prepayment risk. A decline or flattening of housing values may cause delinquencies in mortgages (especially sub-prime or non-prime mortgages) underlying mortgage-backed securities and thereby adversely affect the ability of the mortgage-backed securities issuer to make principal and/or interest payments to mortgage-backed securities holders, including the Fund. Rising or high interest rates tend to extend the duration of mortgage-backed securities, making their prices more volatile and more sensitive to changes in interest rates.
F/m Accumulator Mortgage REIT Fund | Mortgage REIT Risk  
Prospectus [Line Items]  
Risk [Text Block]
Mortgage REIT Risk. Mortgage REITs are exposed to risks specific to the real estate market, including, but not limited to, credit risk, interest rate risk and leverage risk and other risks that relate specifically to the way in which Mortgage REITs are organized and operated. Mortgage REITs receive principal and interest payments from the owners of the mortgaged properties. Accordingly, Mortgage REITs are subject to the credit risk of the borrowers. Credit risk refers to the possibility that the borrower will be unable and/or unwilling to make timely interest payments and/or repay the principal on the loan to a Mortgage REIT when due. To the extent that a Mortgage REIT invests in mortgage-backed securities offered by private issuers, such as commercial banks, savings and loan institutions, private mortgage insurance companies, mortgage bankers and other secondary market issuers, the Mortgage REIT may be subject to additional risks. Timely payment of interest and principal of non-governmental issuers may be supported by various forms of private insurance or guarantees, including individual loan, title, pool and hazard insurance purchased by the issuer. However, there can be no assurance that the private insurers can or will meet their obligations under such policies. Unexpected high rates of default on the mortgages held by a mortgage pool may adversely affect the value of a mortgage-backed security and could result in losses to a Mortgage REIT. The risk of such defaults is generally higher in the case of mortgage pools that include subprime mortgages. To the extent that a Mortgage REIT’s portfolio is exposed to lower-rated, unsecured or subordinated instruments, the risk of loss may increase, which may have a negative impact on the Fund.

 

Mortgage REITs also are subject to the risk that the value of mortgaged properties may be less than the amounts owed on the properties. If a Mortgage REIT is required to foreclose on a borrower, the amount recovered in connection with the foreclosure may be less than the amount owed to the Mortgage REIT. Mortgage REITs are subject to significant interest rate risk. Interest rate risk refers to fluctuations in the value of a Mortgage REIT’s investment in fixed rate obligations resulting from changes in the general level of interest rates. When the general level of interest rates goes up, the value of a Mortgage REIT’s investment in fixed rate obligations goes down. Mortgage REITs typically use leverage and many are highly leveraged, which exposes them to leverage risk and the risks generally associated with debt financing. Leverage risk refers to the risk that leverage created from borrowing may impair a Mortgage REIT’s liquidity, cause it to liquidate positions at an unfavorable time and increase the volatility of the values of securities issued by the Mortgage REIT. The use of leverage may not be advantageous to a Mortgage REIT. The success of using leverage is dependent on whether the return earned on the investments made using the proceeds of leverage exceed the cost of using leverage. To the extent that a Mortgage REIT incurs significant leverage, it may incur substantial losses if its borrowing costs increase. Borrowing costs may increase for any of the following reasons: short-term interest rates increase; the market value of a Mortgage REIT’s assets decrease; interest rate volatility increases; or the availability of financing in the market decreases. During periods of adverse market conditions, downturns in the economy or deterioration in the conditions of the Mortgage REIT’s mortgage-related assets, the use of leverage may cause a Mortgage REIT to lose more money than would have been the case if leverage was not used.

 

Mortgage REITs are subject to prepayment risk, which is the risk that borrowers may prepay their mortgage loans at faster than expected rates. Prepayment rates generally increase when interest rates fall and decrease when interest rates rise. These faster than expected payments may adversely affect a Mortgage REIT’s profitability because the Mortgage REIT may be forced to replace investments that have been redeemed or repaid early with other investments having a lower yield. Additionally, rising interest rates may cause the duration of a Mortgage REIT’s investments to be longer than anticipated and increase such investments’ interest rate sensitivity. REITs generally are subject to special U.S. federal tax requirements. A REIT’s failure to comply with these requirements may negatively affect its performance. Mortgage REITs may be dependent upon the management skills and may have limited financial resources. Mortgage REITs are generally not diversified and may be subject to heavy cash flow dependency, default by borrowers and self-liquidation. In addition, transactions between Mortgage REITs and their affiliates may be subject to conflicts of interest which may adversely affect a Mortgage REIT’s shareholders.

F/m Accumulator Mortgage REIT Fund | Mortgage Finance Companies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Mortgage Finance Companies Risk. Mortgage finance companies are subject to the credit risk of their borrowers, the risk that the value of a mortgaged property may be less than the amount owed on the property, and interest rate risk, among other risks.
F/m Accumulator Mortgage REIT Fund | Real Estate Company Risk  
Prospectus [Line Items]  
Risk [Text Block]
Real Estate Company Risk. Real estate companies, which include REITs, real estate holding and operating companies, and real estate management or development companies, expose investors to the risks of owning real estate directly as well as to the risks from the way that such companies operate. Real estate is highly sensitive to general and local economic conditions and can be subject to intense competition and periodic overbuilding. Other real estate risks include decreases in property values, tax increases, zoning changes, casualty or condemnation losses, environmental liabilities, regulatory limitations on rent or eviction, and defaults by borrowers or tenants. Real estate companies may be heavily invested in one geographic region, industry or property type. They also may be highly leveraged, which can magnify losses, and interest rate increases can make it difficult to obtain financing and service debt.
F/m Accumulator Mortgage REIT Fund | REITs Risk  
Prospectus [Line Items]  
Risk [Text Block]
REITs Risk. Investing in REITs exposes investors to the risks of owning real estate directly, as well as to risks that relate specifically to the way in which REITs are organized and operated. REITs generally invest directly in real estate, in mortgages or in some combination of the two. Operating REITs requires specialized management skills and the Fund indirectly bears management expenses along with the direct expenses of the Fund. Individual REITs may own a limited number of properties and may concentrate in a particular region or property type. REITs may also be subject to heavy cash flow dependency, default by borrowers or tenants and self-liquidation. REITs also must satisfy specific requirements of the Internal Revenue Code in order to qualify for tax-free pass-through income. The failure of a company to qualify as a REIT could have adverse consequences for the Fund, including significantly reducing the return to the Fund on its investment in such company. In addition, REITs, like mutual funds, have expenses, including management and administration fees, that are paid by their shareholders. As a result, shareholders will absorb their proportionate share of duplicate levels of fees when the Fund invests in REITs.
F/m Accumulator Mortgage REIT Fund | Sector Risk  
Prospectus [Line Items]  
Risk [Text Block]
Sector Risk. To the extent the Fund invests more heavily in particular sectors of the economy, its performance will be especially sensitive to developments that significantly affect those sectors.

 

oFinancial Sector Risk. The Fund may be sensitive to, and its performance may depend to a greater extent on, the overall condition of the financial sector. Companies in the financial sector may be subject to extensive government regulation that affects the scope of their activities, the prices they can charge and the amount of capital they must maintain. The profitability of companies in the financial sector may be adversely affected by increases in interest rates, by loan losses, which usually increase in economic downturns, and by credit rating downgrades. In addition, the financial sector is undergoing numerous changes, including continuing consolidations, development of new products and structures and changes to its regulatory framework. Furthermore, some companies in the financial sector perceived as benefiting from government intervention in the past may be subject to future government-imposed restrictions on their businesses or face increased government involvement in their operations. Increased government involvement in the financial sector, including measures such as taking ownership positions in financial institutions, could result in a dilution of the Fund’s investments in financial institutions.

 

oReal Estate Sector Risk. Companies in the real estate sector include companies that invest in real estate, such as REITs and real estate management and development companies. The Fund may be sensitive to changes in, and its performance may depend to a greater extent on, the overall condition of the real estate sector. Companies that invest in real estate are subject to the risks of owning real estate directly as well as to risks that relate specifically to the way that such companies operate, including management risk (such companies are dependent upon the management skills of a few key individuals and may have limited financial resources). Adverse economic, business or political developments affecting real estate could have a major effect on the values of the Fund’s investments. Investing in real estate is subject to such risks as decreases in real estate values, overbuilding, increased competition and other risks related to local or general economic conditions, increases in operating costs and property taxes, changes in zoning laws, casualty or condemnation losses, possible environmental liabilities, regulatory limitations on rent, possible lack of availability of mortgage financing, market saturation, fluctuations in rental income and the value of underlying properties and extended vacancies of properties. Certain real estate securities have a relatively small market capitalization, which may tend to increase the volatility of the market price of these securities. Real estate securities have limited diversification and are, therefore, subject to risks inherent in operating and financing a limited number of projects. Real estate securities are also subject to heavy cash flow dependency and defaults by borrowers or tenants.
F/m Accumulator Mortgage REIT Fund | Small and Medium Capitalization Companies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Small and Medium Capitalization Companies Risk. The Fund may invest in small and medium capitalization companies and, therefore, will be subject to certain risks associated with small and medium capitalization companies. These companies are often subject to less analyst coverage and may be in early and less predictable periods of their corporate existences, with little or no record of profitability. In addition, these companies often have greater price volatility, lower trading volume and less liquidity than larger, more established companies. These companies tend to have smaller revenues, narrower product lines, less management depth and experience, smaller shares of their product or service markets, fewer financial resources and less competitive strength than large-capitalization companies. Returns on investments in securities of small and medium capitalization companies could trail the returns on investments in securities of larger companies.
F/m Accumulator Mortgage REIT Fund | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] As a result, you may lose money on your investment in the Fund, and there can be no assurance that the Fund will achieve its investment objective.
F/m Accumulator Mortgage REIT Fund | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Non-Diversification Risk. The Fund is classified as “non-diversified” under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Code. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers. Additionally, to the extent that the Fund invests a significant percentage of its assets in a single asset class or industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified. Because the Fund expects to invest a significant portion of its assets in the real estate sector, it may be more susceptible to adverse economic or regulatory occurrences affecting this sector, such as changes in interest rates, loan concentration, government regulation and competition.
F/m Accumulator Equity REIT Fund | Active Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Active Management Risk. The Fund is actively managed using proprietary investment strategies and processes. There can be no guarantee that these strategies and processes will be successful or that the Fund will achieve its investment objective.
F/m Accumulator Equity REIT Fund | Affiliated Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
Affiliated Fund Risk. Affiliated fund risk is the risk that the Adviser may select Underlying Funds and/or investments for the Fund based on its own financial interests or other business considerations rather than the Fund’s interests. The Adviser may be subject to potential conflicts of interest in selecting the Underlying Funds because affiliated Underlying Funds pay an advisory fee to the Adviser based on their assets, the fees paid to the Adviser by some affiliated Underlying Funds may be higher than those paid by other Underlying Funds or the Underlying Funds may be in need of assets to enhance their appeal to other investors, liquidity and trading and/or to enable them to carry out their investment strategies. However, the Adviser is a fiduciary to the Fund and is legally obligated to act in the Fund’s best interest when selecting Underlying Funds.
F/m Accumulator Equity REIT Fund | Asset Class Risk  
Prospectus [Line Items]  
Risk [Text Block]
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market, or other asset classes.
F/m Accumulator Equity REIT Fund | Call Risk  
Prospectus [Line Items]  
Risk [Text Block]
Call Risk. During periods of falling interest rates, an issuer of a callable bond held by an Underlying Fund may “call” or repay the security before its stated maturity, and the Underlying Fund may have to reinvest the proceeds in securities with lower yields, which would result in a decline in the Fund’s performance, or in securities with greater risks or with other less favorable features.
F/m Accumulator Equity REIT Fund | Cash or Cash Equivalents Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cash or Cash Equivalents Risk. At any time, the Fund may have significant investments in cash or cash equivalents. When a substantial portion of a portfolio is held in cash or cash equivalents, there is the risk that the value of the cash account, including interest, will not keep pace with inflation, thus reducing purchasing power over time. Additionally, in rising markets, holding cash or cash equivalents may adversely affect the Fund’s performance and the Fund may not achieve its investment objectives.
F/m Accumulator Equity REIT Fund | Concentration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in a particular issue, issuer or issuers, country, market segment, or asset class.
F/m Accumulator Equity REIT Fund | Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Credit Risk. The value of your investment in the Fund may change in response to changes in the credit ratings of the Fund’s portfolio securities, including with respect to Underlying Funds. Generally, investment risk and price volatility increase as a security’s credit rating declines. The financial condition of an issuer of a fixed income security held by such Fund or an Underlying Fund may cause it to default or become unable to pay interest or principal due on the security.
F/m Accumulator Equity REIT Fund | Cyber Security Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to the Fund’s assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent the Fund’s investors from purchasing, redeeming or exchanging Shares or receiving distributions. While the Fund and the Adviser have established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Further, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, or issuers of securities in which the Fund invests. The Fund and the Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or the Adviser. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders. Issuers of securities in which the Fund invests are also subject to cyber security risks, and the value of these securities could decline if the issuers experience cyberattacks or other cyber-failures.
F/m Accumulator Equity REIT Fund | Derivatives Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk. Derivatives and other similar instruments (referred to collectively as “derivatives”) are financial instruments whose values are based on the value of one or more reference assets or indicators, such as a security, currency, interest rate, or index. The Fund’s use of derivatives involves risks different from, and possibly greater than, the risks associated with investing directly in securities and other more traditional investments. Moreover, although the value of a derivative is based on an underlying asset or indicator, a derivative typically does not carry the same rights as would be the case if the Fund invested directly in the underlying securities, currencies or other assets.

 

Derivatives are subject to a number of risks, such as potential changes in value in response to market developments or, in the case of “over-the-counter” derivatives, as a result of a counterparty’s credit quality and the risk that a derivative transaction may not have the effect the Adviser anticipated. Derivatives also involve the risk of mispricing or improper valuation and the risk that changes in the value of a derivative may not achieve the desired correlation with the underlying asset or indicator. Derivative transactions can create investment leverage and may be highly volatile, and the Fund could lose more than the amount it invests. The use of derivatives may increase the amount and affect the timing and character of taxes payable by shareholders of the Fund.

 

Many derivative transactions are entered into “over-the-counter” without a central clearinghouse; as a result, the value of such a derivative transaction will depend on, among other factors, the ability and the willingness of the Fund’s counterparty to perform its obligations under the transaction. If a counterparty were to default on its obligations, the Fund’s contractual remedies against such counterparty may be subject to bankruptcy and insolvency laws, which could affect the Fund’s rights as a creditor (e.g., the Fund may not receive the net amount of payments that it is contractually entitled to receive). Counterparty risk also refers to the related risks of having concentrated exposure to such a counterparty. A liquid secondary market may not always exist for the Fund’s derivative positions at any time, and the Fund may not be able to initiate or liquidate a swap position at an advantageous time or price, which may result in significant losses. The Fund may also face the risk that it may not be able to meet margin and payment requirements and maintain a derivatives position.

 

Derivatives are also subject to operational and legal risks. Operational risk generally refers to risk related to potential operational issues, including documentation issues, settlement issues, system failures, inadequate controls, and human errors. Legal risk generally refers to insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract.

F/m Accumulator Equity REIT Fund | Derivatives Counterparty Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Counterparty Risk. A loss may be sustained as a result of the failure of another party to a contract (usually referred to as a “counterparty”) to make required payments, fulfill its contractual obligations or otherwise comply with a contract’s terms because of the financial condition of the counterparty (i.e., financial difficulties or insolvency), market activities and developments, the counterparty being unable or unwilling to perform under the contract or other reasons. In a swap agreement, the Fund bears the risk of loss of the amount expected to be received under the agreement in the event of the default or bankruptcy of a counterparty. These risks are heightened and may materially impact the Fund’s ability to achieve its investment objective given that the Fund may enter into swap agreements with one or a limited number of counterparties. The Fund’s use of one or a limited number of counterparties increases the Fund’s exposure to counterparty credit risk. Credit risk refers to the possibility that the counterparty will be unable and/or unwilling to honor its obligations and/or default completely on the derivative transaction. Swap agreements also may be considered to be illiquid. Further, there is a risk that no suitable counterparties are willing to enter into, or continue to enter into, transactions with the Fund and, as a result, the Fund may not be able to achieve its investment objective.
F/m Accumulator Equity REIT Fund | Duration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Duration Risk. Duration is a measure of the price sensitivity of a debt security or portfolio to interest rate changes. Duration risk is the risk that longer-duration debt securities will be more volatile and thus more likely to decline in price, and to a greater extent, in a rising interest rate environment than shorter-duration debt securities.
F/m Accumulator Equity REIT Fund | Equity Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Equity Securities Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the markets in which the issuers of securities held by the Fund participate, or factors relating to specific issuers in which the Fund invests. Equity securities are subordinated to preferred securities and debt in a company’s capital structure with respect to priority to a share of corporate income, and therefore will be subject to greater dividend risk than preferred securities or debt instruments. In addition, while broad market measures of equity securities have historically generated higher average returns than fixed income securities, equity securities have generally also experienced significantly more volatility in those returns.
F/m Accumulator Equity REIT Fund | ETF Risk  
Prospectus [Line Items]  
Risk [Text Block]
ETF Risk. The Fund is an ETF, and, as a result of an ETF’s structure, it is exposed to the following risks:

 

oAuthorized Participants, Market Makers and Liquidity Providers Concentration Risk. Only an authorized participant (“AP”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that are institutional investors and may act as APs. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent either of the following events occur, there may be significantly diminished trading in Fund Shares, Fund Shares may trade at a material discount to net asset value (“NAV”), and Fund Shares may possibly face delisting: (i) if APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services, or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform their functions. These events, among others, may lead to Fund Shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than the NAV when you buy Shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those Shares in the secondary market. A diminished market for an ETF’s shares substantially increases the risk that a shareholder may pay considerably more or receive significantly less than the underlying value of the ETF shares bought or sold. In periods of market volatility, APs, market makers and/or liquidity providers may be less willing to transact in Fund Shares.

 

oSecondary Market Trading Risk. Although Shares are intended to be listed on a national securities exchange, The Nasdaq Stock Market LLC (the “Exchange”), and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Shares on the Exchange may be halted. During periods of market stress, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines.

 

oShares May Trade at Prices Other Than NAV Risk. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Shares trade on a stock exchange at prices at, above, or below the Fund’s most recent NAV. The Fund’s NAV is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings. The trading price of the Shares fluctuates continuously throughout trading hours on the exchange, based on both the relative market supply of, and demand for, the Shares and the underlying value of the Fund’s portfolio holdings. As a result, the trading prices of the Shares may deviate from the Fund’s NAV. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. Any of these factors, among others, may lead to the Shares trading at a premium or discount to NAV.

 

To the extent the Fund invests in Underlying Funds, which are also ETFs, the Fund will be further exposed to the above ETF risks.

F/m Accumulator Equity REIT Fund | Futures Risk  
Prospectus [Line Items]  
Risk [Text Block]
Futures Risk. Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.
F/m Accumulator Equity REIT Fund | High Portfolio Turnover Risk  
Prospectus [Line Items]  
Risk [Text Block]
High Portfolio Turnover Risk. Active and frequent trading of the Fund’s portfolio securities may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.
F/m Accumulator Equity REIT Fund | Income Risk  
Prospectus [Line Items]  
Risk [Text Block]
Income Risk. Under certain market conditions, the Fund may invest in Underlying Funds that are subject to income risk. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
F/m Accumulator Equity REIT Fund | Inflation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Inflation Risk. Under certain market conditions, the Fund may invest in an Underlying Fund that is subject to inflation risk. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets may decline.
F/m Accumulator Equity REIT Fund | Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Interest-Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt instruments tend to fall, and if interest rates fall, the values of debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates, which may negatively affect the value of debt instruments held by the Fund and have a negative impact on the Fund’s performance and NAV. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. The historically low-interest rate environment in recent years heightens the risks associated with rising interest rates.
F/m Accumulator Equity REIT Fund | Investment Restriction Risk  
Prospectus [Line Items]  
Risk [Text Block]
Investment Restriction Risk. The Fund is subject to the conditions set forth in certain provisions of the 1940 Act and SEC regulations thereunder that limit the amount that the Fund and its affiliates, in the aggregate, can invest in the outstanding voting securities of an unaffiliated investment company or business development company. The Fund and its affiliates may not actively acquire “control” of an investment company or business development company, which is presumed once ownership of an investment company’s outstanding voting securities exceeds 25%. Also, to comply with provisions of the 1940 Act and regulations thereunder, the Adviser may be required to vote shares of an investment company or business development company in the same general proportion as shares held by other shareholders of the investment company or business development company.
F/m Accumulator Equity REIT Fund | Issuer Risk  
Prospectus [Line Items]  
Risk [Text Block]
Issuer Risk. The performance of the Fund’s investment in Underlying Funds depends on the performance of individual securities or other assets to which the Underlying Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
F/m Accumulator Equity REIT Fund | Liquidity Risk  
Prospectus [Line Items]  
Risk [Text Block]
Liquidity Risk. Certain securities held by an Underlying Fund may be difficult (or impossible) to sell at the time and at the price the Adviser would like. As a result, an Underlying Fund may have to hold these securities longer than it would like and may forego other investment opportunities. There is the possibility that an Underlying Fund may lose money or be prevented from realizing capital gains if it cannot sell a security at a particular time and price.
F/m Accumulator Equity REIT Fund | Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Management Risk. The Fund is subject to management risk, which is the risk that the Adviser’s analysis of economic conditions and expectations regarding interest rate changes may fail to produce the intended results. In other words, the individual investments of the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.
F/m Accumulator Equity REIT Fund | Market Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Risk. Economies and financial markets throughout the world are becoming increasingly interconnected, which increases the likelihood that events or conditions in one country or region will adversely impact markets or issuers in other countries or regions. The value of the Fund and/or the Underlying Fund’s investments may be negatively affected by adverse changes in overall economic or market conditions, such as the level of economic activity and productivity, unemployment and labor force participation rates, inflation or deflation (and expectations for inflation or deflation), interest rates, demand and supply for particular products or resources including labor, and debt levels and credit ratings, among other factors. Such adverse conditions may contribute to an overall economic contraction across entire economies or markets, which may negatively impact the profitability of issuers operating in those economies or markets. The Fund and the Underlying Funds are subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. The Fund’s and the Underlying Funds’ NAVs and market prices may fluctuate significantly in response to these and other factors including economic, political, or financial events, public health crises (such as epidemics or pandemics), or other disruptive events (whether real, expected or perceived) in the U.S. and global markets. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. As a result, an investor could lose money over short or long periods of time.
F/m Accumulator Equity REIT Fund | Market Price Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Price Risk. Fund Shares are listed for trading on an exchange and are bought and sold in the secondary market at market prices. The market prices of Shares will fluctuate, in some cases materially, in response to changes in the NAV and supply and demand for Shares. As a result, the trading prices of Shares may deviate significantly from the NAV during periods of market volatility. The Adviser cannot predict whether Shares will trade above, below or at their NAV. Given the fact that Shares can be created and redeemed in Creation Units (defined below), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained in the long term. If market makers exit the business or are unable to continue making markets in Fund Shares, Shares may trade at a discount to NAV like closed-end fund shares and may even face delisting (that is, investors would no longer be able to trade Shares in the secondary market). Further, while the creation/redemption feature is designed to make it likely that Shares normally will trade close to the value of the Fund’s holdings, disruptions to creations and redemptions, including disruptions at market makers, APs or market participants, or during periods of significant market volatility, may result in market prices that differ significantly from the value of the Fund’s holdings. Although market makers will generally take advantage of differences between the NAV and the market price of Fund Shares through arbitrage opportunities, there is no guarantee that they will do so. In addition, the securities held by the Fund may be traded in markets that close at a different time than the exchange on which the Fund’s Shares trade. Liquidity in those securities may be reduced after the applicable closing times. Accordingly, during the time when the exchange is open but after the applicable market closing, fixing or settlement times, bid-ask spreads and the resulting premium or discount to the Shares’ NAV are likely to widen. Further, secondary markets may be subject to irregular trading activity, wide bid-ask spreads and extended trade settlement periods, which could cause a material decline in the Fund’s NAV. The Fund’s investment results are measured based upon the daily NAV of the Fund. Investors purchasing and selling Shares in the secondary market may not experience investment results consistent with those experienced by those APs creating and redeeming Shares directly with the Fund.
F/m Accumulator Equity REIT Fund | Market Trading Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund Shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund Shares. Any of these factors, among others, may lead to the Fund’s Shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund Shares at a time when the market price is at a premium to NAV or sell Fund Shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund Shares.
F/m Accumulator Equity REIT Fund | New Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
New Fund Risk. The Fund is a newly-organized management investment company with a limited operating history. In addition, there can be no assurance that the Fund will grow to, or maintain, an economically viable size, in which case the Board of Directors (the “Board”) of The RBB Fund, Inc. (the “Company”) may determine to liquidate the Fund.
F/m Accumulator Equity REIT Fund | Operational Risk  
Prospectus [Line Items]  
Risk [Text Block]
Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties, or other third parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
F/m Accumulator Equity REIT Fund | Options Risk  
Prospectus [Line Items]  
Risk [Text Block]
Options Risk. If the Fund purchases a call option, it receives, in return for the premium it pays, the right to buy from the writer of the option the underlying security at a specified price at any time before the option expires. The Fund purchases call options in anticipation of an increase in the market value of securities that it intends ultimately to buy. During the life of the call option, the Fund is able to buy the underlying security at the exercise price regardless of any increase in the market price of the underlying security. In order for a call option to result in a gain, the market price of the underlying security must exceed the sum of the exercise price, the premium paid, and transaction costs.
F/m Accumulator Equity REIT Fund | Premium/Discount Risk  
Prospectus [Line Items]  
Risk [Text Block]
Premium/Discount Risk. The market price of the Fund’s Shares will generally fluctuate in accordance with changes in the Fund’s NAV as well as the relative supply of and demand for Shares on the Exchange. The Adviser cannot predict whether Shares will trade below, at, or above their NAV because the Shares trade on the Exchange at market prices and not at NAV. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for Shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that Shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAV), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained. During stressed market conditions, the market for the Fund’s Shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying holdings, which could in turn lead to differences between the market price of the Fund’s Shares and their NAV and the bid/ask spread on the Fund’s Shares may widen.
F/m Accumulator Equity REIT Fund | Prepayment and Extension Risk  
Prospectus [Line Items]  
Risk [Text Block]
Prepayment and Extension Risk. When interest rates fall, issuers of high interest debt obligations may pay off the debts earlier than expected (prepayment risk), and the Fund may have to reinvest the proceeds at lower yields. When interest rates rise, issuers of lower interest debt obligations may pay off the debts later than expected (extension risk), thus keeping the Fund’s assets tied up in lower interest debt obligations. Ultimately, any unexpected behavior in interest rates could increase the volatility of the Fund’s Share price and yield and could hurt Fund performance. Prepayments could also create capital gains tax liability in some instances.
F/m Accumulator Equity REIT Fund | Pricing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Pricing Risk. If market conditions make it difficult to value some investments, the Fund may value these investments using more subjective methods, such as fair value pricing. In such cases, the value determined for an investment could be different from the value realized upon such investment’s sale. As a result, you could pay more than the market value when buying Fund Shares or receive less than the market value when selling Fund Shares.
F/m Accumulator Equity REIT Fund | Rating Agencies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Rating Agencies Risk. Ratings are not an absolute standard of quality, but rather general indicators that reflect only the view of the originating rating agencies from which an explanation of the significance of such ratings may be obtained. There is no assurance that a particular rating will continue for any given period of time or that any such rating will not be revised downward or withdrawn entirely if, in the judgment of the agency establishing the rating, circumstances so warrant. A downward revision or withdrawal of such ratings, or either of them, may have an effect on the liquidity or market price of the securities in which an Underlying Fund invests.
F/m Accumulator Equity REIT Fund | Regulatory Risk  
Prospectus [Line Items]  
Risk [Text Block]
Regulatory Risk. Changes in the laws or regulations of the United States, including any changes to applicable tax laws and regulations, could impair the ability of the Fund to achieve its investment objective and could increase the operating expenses of the Fund. The Adviser is operating under an exemption from the U.S. Commodity Exchange Act and the rules of the Commodity Futures Trading Commission (the “CFTC”); however, it may register as a commodity pool operator at a future date, at which time it would be subject to CFTC regulation with respect to the Fund. To the extent that the Adviser is required to register with the CFTC, the CFTC has adopted rules regarding the disclosure, reporting and recordkeeping requirements that will apply with respect to applicable funds. Generally, these rules allow for substituted compliance with CFTC disclosure and shareholder reporting requirements, based on the Adviser’s compliance with comparable SEC requirements. This means that for most of the CFTC’s disclosure and shareholder reporting applicable to the Adviser as a fund’s commodity pool operator, the Adviser’s compliance with SEC disclosure and shareholder reporting would be deemed to fulfill the Adviser’s CFTC obligations. However, if a fund is regulated by the CFTC, such fund may incur additional compliance and other expenses.
F/m Accumulator Equity REIT Fund | Reinvestment Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reinvestment Risk. Reinvestment risk is the risk that the Fund’s portfolio will decline if and when the Fund reinvests the proceeds from the disposition of its portfolio securities at market interest rates that are below the portfolio’s current earnings rate. A decline in income could negatively affect the market price of the Shares.
F/m Accumulator Equity REIT Fund | Reverse Repurchase Agreements Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reverse Repurchase Agreements Risk. Reverse repurchase agreements are a form of secured borrowing and subject the Fund to the risks associated with leverage, including exposure to potential gains and losses in excess of the amount invested, resulting in an increase in the speculative character of the Fund’s outstanding Shares. Reverse repurchase agreements involve the risk that the investment return earned by the Fund (from the investment of the proceeds) will be less than the interest expense of the transaction, that the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities, and that the other party may fail to return the securities in a timely manner or at all.
F/m Accumulator Equity REIT Fund | Risk of Investing in the U.S.  
Prospectus [Line Items]  
Risk [Text Block]
Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
F/m Accumulator Equity REIT Fund | Securities Lending Risk  
Prospectus [Line Items]  
Risk [Text Block]
Securities Lending Risk. The Fund may engage in securities lending (i.e., lend portfolio securities to institutions, such as certain broker-dealers). Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investment made with cash collateral. These events could also trigger adverse tax consequences for the Fund. The Fund could also experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.
F/m Accumulator Equity REIT Fund | Swaps Risk  
Prospectus [Line Items]  
Risk [Text Block]
Swaps Risk. The Fund will invest in swap agreements, which may be less liquid than other types of investments. The illiquidity of swap agreements could have a negative effect on the Fund’s ability to achieve its investment objective and may result in losses to Fund shareholders. In stressed market conditions, the liquidity of the Fund’s Shares may begin to mirror those of the underlying portfolio holdings, which can be significantly less liquid than the Fund’s Shares.
F/m Accumulator Equity REIT Fund | Tax Risk  
Prospectus [Line Items]  
Risk [Text Block]
Tax Risk. Because the Fund is expected to invest in the Underlying Funds, distributions of short-term capital gains by an Underlying Fund will be recognized as ordinary income by the Fund and would not be offset by the Fund’s capital loss carryforwards, if any. Capital loss carryforwards of an Underlying Fund, if any, will not be available to offset net capital gains of the Fund. Further, the Fund’s realized losses on sales of shares of an Underlying Fund may be indefinitely or permanently deferred as “wash sales” to the extent it re-acquires shares of the same Underlying Fund within the 61-day period beginning 30 days prior to the disposition date.
F/m Accumulator Equity REIT Fund | Underlying Funds Risk  
Prospectus [Line Items]  
Risk [Text Block]
Underlying Funds Risk. The Fund’s investment in shares of Underlying Funds subjects it to the risks of owning the securities of the Underlying Fund, as well as the same structural risks faced by an investor purchasing shares of the Underlying Fund, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses. Since the Fund invests in the Underlying Funds, the Fund’s investment performance and risks are likely to be directly related to those of the Underlying Funds. The Fund’s NAV will change with changes in the value of the Underlying Funds and other assets that the Fund holds. The shares of an Underlying Fund may trade at a premium or discount to the Underlying Fund’s NAV. Investors in the Fund will indirectly bear the expenses charged by the Underlying Funds, and an investment in the Fund may entail more expenses than a direct investment in the Underlying Funds.
F/m Accumulator Equity REIT Fund | U.S. Government Obligations Risk  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.
F/m Accumulator Equity REIT Fund | Valuation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Valuation Risk. The prices provided by the Fund’s pricing services or independent dealers or the fair value determinations made by the valuation committee of the Adviser may be different from the prices used by other funds or from the prices at which securities are actually bought and sold. The prices of certain securities provided by pricing services may be subject to frequent and significant change, and will vary depending on the information that is available.
F/m Accumulator Equity REIT Fund | Large Capitalization Company Risk  
Prospectus [Line Items]  
Risk [Text Block]
Large Capitalization Company Risk. Large capitalization (“Large-cap”) companies are generally more mature and the securities issued by these companies may not be able to reach the same levels of growth as the securities issued by small- or middle-capitalization companies.
F/m Accumulator Equity REIT Fund | Market Capitalization Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Capitalization Risk. Securities issued by companies of different market capitalizations tend to go in and out of favor based on market and economic conditions. During a period when securities of a particular market capitalization fall behind other types of investments, the Fund’s performance could be impacted.
F/m Accumulator Equity REIT Fund | Real Estate Company Risk  
Prospectus [Line Items]  
Risk [Text Block]
Real Estate Company Risk. Real estate companies, which include REITs, real estate holding and operating companies, and real estate management or development companies, expose investors to the risks of owning real estate directly as well as to the risks from the way that such companies operate. Real estate is highly sensitive to general and local economic conditions and can be subject to intense competition and periodic overbuilding. Other real estate risks include decreases in property values, tax increases, zoning changes, casualty or condemnation losses, environmental liabilities, regulatory limitations on rent or eviction, and defaults by borrowers or tenants. Real estate companies may be heavily invested in one geographic region, industry or property type. They also may be highly leveraged, which can magnify losses, and interest rate increases can make it difficult to obtain financing and service debt.
F/m Accumulator Equity REIT Fund | REITs Risk  
Prospectus [Line Items]  
Risk [Text Block]
REITs Risk. Investing in REITs exposes investors to the risks of owning real estate directly, as well as to risks that relate specifically to the way in which REITs are organized and operated. REITs generally invest directly in real estate, in mortgages or in some combination of the two. Operating REITs requires specialized management skills and the Fund indirectly bears management expenses along with the direct expenses of the Fund. Individual REITs may own a limited number of properties and may concentrate in a particular region or property type. REITs may also be subject to heavy cash flow dependency, default by borrowers or tenants and self-liquidation. REITs also must satisfy specific requirements of the Code in order to qualify for tax-free pass-through income. The failure of a company to qualify as a REIT could have adverse consequences for the Fund, including significantly reducing the return to the Fund on its investment in such company. In addition, REITs, like mutual funds, have expenses, including management and administration fees, that are paid by their shareholders. As a result, shareholders will absorb their proportionate share of duplicate levels of fees when the Fund invests in REITs.
F/m Accumulator Equity REIT Fund | Sector Risk  
Prospectus [Line Items]  
Risk [Text Block]
Sector Risk. To the extent the Fund invests more heavily in particular sectors of the economy, its performance will be especially sensitive to developments that significantly affect those sectors.

 

oFinancial Sector Risk. The Fund may be sensitive to, and its performance may depend to a greater extent on, the overall condition of the financial sector. Companies in the financial sector may be subject to extensive government regulation that affects the scope of their activities, the prices they can charge and the amount of capital they must maintain. The profitability of companies in the financial sector may be adversely affected by increases in interest rates, by loan losses, which usually increase in economic downturns, and by credit rating downgrades. In addition, the financial sector is undergoing numerous changes, including continuing consolidations, development of new products and structures and changes to its regulatory framework. Furthermore, some companies in the financial sector perceived as benefiting from government intervention in the past may be subject to future government-imposed restrictions on their businesses or face increased government involvement in their operations. Increased government involvement in the financial sector, including measures such as taking ownership positions in financial institutions, could result in a dilution of the Fund’s investments in financial institutions.

 

oReal Estate Sector Risk. Companies in the real estate sector include companies that invest in real estate, such as REITs and real estate management and development companies. The Fund may be sensitive to changes in, and its performance may depend to a greater extent on, the overall condition of the real estate sector. Companies that invest in real estate are subject to the risks of owning real estate directly as well as to risks that relate specifically to the way that such companies operate, including management risk (such companies are dependent upon the management skills of a few key individuals and may have limited financial resources). Adverse economic, business or political developments affecting real estate could have a major effect on the values of the Fund’s investments. Investing in real estate is subject to such risks as decreases in real estate values, overbuilding, increased competition and other risks related to local or general economic conditions, increases in operating costs and property taxes, changes in zoning laws, casualty or condemnation losses, possible environmental liabilities, regulatory limitations on rent, possible lack of availability of mortgage financing, market saturation, fluctuations in rental income and the value of underlying properties and extended vacancies of properties. Certain real estate securities have a relatively small market capitalization, which may tend to increase the volatility of the market price of these securities. Real estate securities have limited diversification and are, therefore, subject to risks inherent in operating and financing a limited number of projects. Real estate securities are also subject to heavy cash flow dependency and defaults by borrowers or tenants.
F/m Accumulator Equity REIT Fund | Small and Medium Capitalization Companies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Small and Medium Capitalization Companies Risk. The Fund may invest in small and medium capitalization companies and, therefore, will be subject to certain risks associated with small and medium capitalization companies. These companies are often subject to less analyst coverage and may be in early and less predictable periods of their corporate existences, with little or no record of profitability. In addition, these companies often have greater price volatility, lower trading volume and less liquidity than larger, more established companies. These companies tend to have smaller revenues, narrower product lines, less management depth and experience, smaller shares of their product or service markets, fewer financial resources and less competitive strength than large-capitalization companies. Returns on investments in securities of small and medium capitalization companies could trail the returns on investments in securities of larger companies.
F/m Accumulator Equity REIT Fund | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] As a result, you may lose money on your investment in the Fund, and there can be no assurance that the Fund will achieve its investment objective.
F/m Accumulator Equity REIT Fund | Risk Nondiversified Status [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Non-Diversification Risk. The Fund is classified as “non-diversified” under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Code. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers. Additionally, to the extent that the Fund invests a significant percentage of its assets in a single asset class or industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified. Because the Fund expects to invest a significant portion of its assets in the real estate sector, it may be more susceptible to adverse economic or regulatory occurrences affecting this sector, such as changes in interest rates, loan concentration, government regulation and competition.
F/m Accumulator High Dividend Payers Fund | Active Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Active Management Risk. The Fund is actively managed using proprietary investment strategies and processes. There can be no guarantee that these strategies and processes will be successful or that the Fund will achieve its investment objective.
F/m Accumulator High Dividend Payers Fund | Affiliated Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
Affiliated Fund Risk. Affiliated fund risk is the risk that the Adviser may select Underlying Funds and/or investments for the Fund based on its own financial interests or other business considerations rather than the Fund’s interests. The Adviser may be subject to potential conflicts of interest in selecting the Underlying Funds because affiliated Underlying Funds pay an advisory fee to the Adviser based on their assets, the fees paid to the Adviser by some affiliated Underlying Funds may be higher than those paid by other Underlying Funds or the Underlying Funds may be in need of assets to enhance their appeal to other investors, liquidity and trading and/or to enable them to carry out their investment strategies. However, the Adviser is a fiduciary to the Fund and is legally obligated to act in the Fund’s best interest when selecting Underlying Funds.
F/m Accumulator High Dividend Payers Fund | Asset Class Risk  
Prospectus [Line Items]  
Risk [Text Block]
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market, or other asset classes.
F/m Accumulator High Dividend Payers Fund | Cash or Cash Equivalents Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cash or Cash Equivalents Risk. At any time, the Fund may have significant investments in cash or cash equivalents. When a substantial portion of a portfolio is held in cash or cash equivalents, there is the risk that the value of the cash account, including interest, will not keep pace with inflation, thus reducing purchasing power over time. Additionally, in rising markets, holding cash or cash equivalents may adversely affect the Fund’s performance and the Fund may not achieve its investment objectives.
F/m Accumulator High Dividend Payers Fund | Concentration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in a particular issue, issuer or issuers, country, market segment, or asset class.
F/m Accumulator High Dividend Payers Fund | Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Credit Risk. The value of your investment in the Fund may change in response to changes in the credit ratings of the Fund’s portfolio securities, including with respect to Underlying Funds. Generally, investment risk and price volatility increase as a security’s credit rating declines. The financial condition of an issuer of a fixed income security held by such Fund or an Underlying Fund may cause it to default or become unable to pay interest or principal due on the security.
F/m Accumulator High Dividend Payers Fund | Cyber Security Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to the Fund’s assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent the Fund’s investors from purchasing, redeeming or exchanging Shares or receiving distributions. While the Fund and the Adviser have established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Further, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, or issuers of securities in which the Fund invests. The Fund and the Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or the Adviser. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders. Issuers of securities in which the Fund invests are also subject to cyber security risks, and the value of these securities could decline if the issuers experience cyberattacks or other cyber-failures.
F/m Accumulator High Dividend Payers Fund | Derivatives Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk. A derivative is an instrument with a value based on the performance of an underlying currency, security, index or other reference asset. The use of derivatives involves risks different from, or greater than, the risks associated with investing in more traditional investments. Derivatives involve costs, may create leverage, and may be illiquid, volatile, and difficult to value. The Fund may not be able to close out or sell a derivative position at a particular time or at an anticipated price. The use of derivatives could also result in a loss if the counterparty to the transaction does not perform as promised, including because of such counterparty’s bankruptcy or insolvency. The investment results achieved by the use of derivatives by the Fund may not match or fully offset changes in the value of the underlying security, index or other reference asset that it was attempting to hedge or the investment opportunity the Fund was attempting to pursue.
F/m Accumulator High Dividend Payers Fund | Equity Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Equity Securities Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the markets in which the issuers of securities held by the Fund participate, or factors relating to specific issuers in which the Fund invests. Equity securities are subordinated to preferred securities and debt in a company’s capital structure with respect to priority to a share of corporate income, and therefore will be subject to greater dividend risk than preferred securities or debt instruments. In addition, while broad market measures of equity securities have historically generated higher average returns than fixed income securities, equity securities have generally also experienced significantly more volatility in those returns.
F/m Accumulator High Dividend Payers Fund | ETF Risk  
Prospectus [Line Items]  
Risk [Text Block]
ETF Risk. The Fund is an ETF, and, as a result of an ETF’s structure, it is exposed to the following risks:

 

oAuthorized Participants, Market Makers and Liquidity Providers Concentration Risk. Only an authorized participant (“AP”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that are institutional investors and may act as APs. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent either of the following events occur, there may be significantly diminished trading in Fund Shares, Fund Shares may trade at a material discount to net asset value (“NAV”), and Fund Shares may possibly face delisting: (i) if APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services, or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform their functions. These events, among others, may lead to Fund Shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than the NAV when you buy Shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those Shares in the secondary market. A diminished market for an ETF’s shares substantially increases the risk that a shareholder may pay considerably more or receive significantly less than the underlying value of the ETF shares bought or sold. In periods of market volatility, APs, market makers and/or liquidity providers may be less willing to transact in Fund Shares.

 

oSecondary Market Trading Risk. Although Shares are intended to be listed on a national securities exchange, The Nasdaq Stock Market LLC (the “Exchange”), and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Shares on the Exchange may be halted. During periods of market stress, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines.

 

oShares May Trade at Prices Other Than NAV Risk. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Shares trade on a stock exchange at prices at, above, or below the Fund’s most recent NAV. The Fund’s NAV is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings. The trading price of the Shares fluctuates continuously throughout trading hours on the exchange, based on both the relative market supply of, and demand for, the Shares and the underlying value of the Fund’s portfolio holdings. As a result, the trading prices of the Shares may deviate from the Fund’s NAV. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. Any of these factors, among others, may lead to the Shares trading at a premium or discount to NAV.

 

To the extent the Fund invests in Underlying Funds, which are also ETFs, the Fund will be further exposed to the above ETF risks.

F/m Accumulator High Dividend Payers Fund | Futures Risk  
Prospectus [Line Items]  
Risk [Text Block]
Futures Risk. Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.
F/m Accumulator High Dividend Payers Fund | High Portfolio Turnover Risk  
Prospectus [Line Items]  
Risk [Text Block]
High Portfolio Turnover Risk. Active and frequent trading of the Fund’s portfolio securities may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.
F/m Accumulator High Dividend Payers Fund | Income Risk  
Prospectus [Line Items]  
Risk [Text Block]
Income Risk. Under certain market conditions, the Fund may invest in Underlying Funds that are subject to income risk. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
F/m Accumulator High Dividend Payers Fund | Inflation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Inflation Risk. Under certain market conditions, the Fund may invest in an Underlying Fund that is subject to inflation risk. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets may decline.
F/m Accumulator High Dividend Payers Fund | Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Interest-Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt instruments tend to fall, and if interest rates fall, the values of debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates, which may negatively affect the value of debt instruments held by the Fund and have a negative impact on the Fund’s performance and NAV. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. The historically low-interest rate environment in recent years heightens the risks associated with rising interest rates.
F/m Accumulator High Dividend Payers Fund | Issuer Risk  
Prospectus [Line Items]  
Risk [Text Block]
Issuer Risk. The performance of the Fund’s investment in Underlying Funds depends on the performance of individual securities or other assets to which the Underlying Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
F/m Accumulator High Dividend Payers Fund | Liquidity Risk  
Prospectus [Line Items]  
Risk [Text Block]
Liquidity Risk. Certain securities held by an Underlying Fund may be difficult (or impossible) to sell at the time and at the price the Adviser would like. As a result, an Underlying Fund may have to hold these securities longer than it would like and may forego other investment opportunities. There is the possibility that an Underlying Fund may lose money or be prevented from realizing capital gains if it cannot sell a security at a particular time and price.
F/m Accumulator High Dividend Payers Fund | Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Management Risk. The Fund is subject to management risk, which is the risk that the Adviser’s analysis of economic conditions and expectations regarding interest rate changes may fail to produce the intended results. In other words, the individual investments of the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.
F/m Accumulator High Dividend Payers Fund | Market Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Risk. Economies and financial markets throughout the world are becoming increasingly interconnected, which increases the likelihood that events or conditions in one country or region will adversely impact markets or issuers in other countries or regions. The value of the Fund and/or the Underlying Fund’s investments may be negatively affected by adverse changes in overall economic or market conditions, such as the level of economic activity and productivity, unemployment and labor force participation rates, inflation or deflation (and expectations for inflation or deflation), interest rates, demand and supply for particular products or resources including labor, and debt levels and credit ratings, among other factors. Such adverse conditions may contribute to an overall economic contraction across entire economies or markets, which may negatively impact the profitability of issuers operating in those economies or markets. The Fund and the Underlying Funds are subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. The Fund’s and the Underlying Funds’ NAVs and market prices may fluctuate significantly in response to these and other factors including economic, political, or financial events, public health crises (such as epidemics or pandemics), or other disruptive events (whether real, expected or perceived) in the U.S. and global markets. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. As a result, an investor could lose money over short or long periods of time.
F/m Accumulator High Dividend Payers Fund | Market Price Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Price Risk. Fund Shares are listed for trading on an exchange and are bought and sold in the secondary market at market prices. The market prices of Shares will fluctuate, in some cases materially, in response to changes in the NAV and supply and demand for Shares. As a result, the trading prices of Shares may deviate significantly from the NAV during periods of market volatility. The Adviser cannot predict whether Shares will trade above, below or at their NAV. Given the fact that Shares can be created and redeemed in Creation Units (defined below), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained in the long term. If market makers exit the business or are unable to continue making markets in Fund Shares, Shares may trade at a discount to NAV like closed-end fund shares and may even face delisting (that is, investors would no longer be able to trade Shares in the secondary market). Further, while the creation/redemption feature is designed to make it likely that Shares normally will trade close to the value of the Fund’s holdings, disruptions to creations and redemptions, including disruptions at market makers, APs or market participants, or during periods of significant market volatility, may result in market prices that differ significantly from the value of the Fund’s holdings. Although market makers will generally take advantage of differences between the NAV and the market price of Fund Shares through arbitrage opportunities, there is no guarantee that they will do so. In addition, the securities held by the Fund may be traded in markets that close at a different time than the exchange on which the Fund’s Shares trade. Liquidity in those securities may be reduced after the applicable closing times. Accordingly, during the time when the exchange is open but after the applicable market closing, fixing or settlement times, bid-ask spreads and the resulting premium or discount to the Shares’ NAV are likely to widen. Further, secondary markets may be subject to irregular trading activity, wide bid-ask spreads and extended trade settlement periods, which could cause a material decline in the Fund’s NAV. The Fund’s investment results are measured based upon the daily NAV of the Fund. Investors purchasing and selling Shares in the secondary market may not experience investment results consistent with those experienced by those APs creating and redeeming Shares directly with the Fund.
F/m Accumulator High Dividend Payers Fund | Market Trading Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund Shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund Shares. Any of these factors, among others, may lead to the Fund’s Shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund Shares at a time when the market price is at a premium to NAV or sell Fund Shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund Shares.
F/m Accumulator High Dividend Payers Fund | New Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
New Fund Risk. The Fund is a newly-organized management investment company with a limited operating history. In addition, there can be no assurance that the Fund will grow to, or maintain, an economically viable size, in which case the Board of Directors (the “Board”) of The RBB Fund, Inc. (the “Company”) may determine to liquidate the Fund.
F/m Accumulator High Dividend Payers Fund | Operational Risk  
Prospectus [Line Items]  
Risk [Text Block]
Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties, or other third parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
F/m Accumulator High Dividend Payers Fund | Options Risk  
Prospectus [Line Items]  
Risk [Text Block]
Options Risk. If the Fund purchases a call option, it receives, in return for the premium it pays, the right to buy from the writer of the option the underlying security at a specified price at any time before the option expires. The Fund purchases call options in anticipation of an increase in the market value of securities that it intends ultimately to buy. During the life of the call option, the Fund is able to buy the underlying security at the exercise price regardless of any increase in the market price of the underlying security. In order for a call option to result in a gain, the market price of the underlying security must exceed the sum of the exercise price, the premium paid, and transaction costs.
F/m Accumulator High Dividend Payers Fund | Premium/Discount Risk  
Prospectus [Line Items]  
Risk [Text Block]
Premium/Discount Risk. The market price of the Fund’s Shares will generally fluctuate in accordance with changes in the Fund’s NAV as well as the relative supply of and demand for Shares on the Exchange. The Adviser cannot predict whether Shares will trade below, at, or above their NAV because the Shares trade on the Exchange at market prices and not at NAV. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for Shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that Shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAV), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained. During stressed market conditions, the market for the Fund’s Shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying holdings, which could in turn lead to differences between the market price of the Fund’s Shares and their NAV and the bid/ask spread on the Fund’s Shares may widen.
F/m Accumulator High Dividend Payers Fund | Pricing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Pricing Risk. If market conditions make it difficult to value some investments, the Fund may value these investments using more subjective methods, such as fair value pricing. In such cases, the value determined for an investment could be different from the value realized upon such investment’s sale. As a result, you could pay more than the market value when buying Fund Shares or receive less than the market value when selling Fund Shares.
F/m Accumulator High Dividend Payers Fund | Rating Agencies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Rating Agencies Risk. Ratings are not an absolute standard of quality, but rather general indicators that reflect only the view of the originating rating agencies from which an explanation of the significance of such ratings may be obtained. There is no assurance that a particular rating will continue for any given period of time or that any such rating will not be revised downward or withdrawn entirely if, in the judgment of the agency establishing the rating, circumstances so warrant. A downward revision or withdrawal of such ratings, or either of them, may have an effect on the liquidity or market price of the securities in which an Underlying Fund invests.
F/m Accumulator High Dividend Payers Fund | Reinvestment Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reinvestment Risk. Reinvestment risk is the risk that the Fund’s portfolio will decline if and when the Fund reinvests the proceeds from the disposition of its portfolio securities at market interest rates that are below the portfolio’s current earnings rate. A decline in income could negatively affect the market price of the Shares.
F/m Accumulator High Dividend Payers Fund | Reverse Repurchase Agreements Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reverse Repurchase Agreements Risk. Reverse repurchase agreements are a form of secured borrowing and subject the Fund to the risks associated with leverage, including exposure to potential gains and losses in excess of the amount invested, resulting in an increase in the speculative character of the Fund’s outstanding Shares. Reverse repurchase agreements involve the risk that the investment return earned by the Fund (from the investment of the proceeds) will be less than the interest expense of the transaction, that the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities, and that the other party may fail to return the securities in a timely manner or at all.
F/m Accumulator High Dividend Payers Fund | Risk of Investing in the U.S.  
Prospectus [Line Items]  
Risk [Text Block]
Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
F/m Accumulator High Dividend Payers Fund | Securities Lending Risk  
Prospectus [Line Items]  
Risk [Text Block]
Securities Lending Risk. The Fund may engage in securities lending (i.e., lend portfolio securities to institutions, such as certain broker-dealers). Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investment made with cash collateral. These events could also trigger adverse tax consequences for the Fund. The Fund could also experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.
F/m Accumulator High Dividend Payers Fund | Swaps Risk  
Prospectus [Line Items]  
Risk [Text Block]
Swaps Risk. The Fund will invest in swap agreements, which may be less liquid than other types of investments. The illiquidity of swap agreements could have a negative effect on the Fund’s ability to achieve its investment objective and may result in losses to Fund shareholders. In stressed market conditions, the liquidity of the Fund’s Shares may begin to mirror those of the underlying portfolio holdings, which can be significantly less liquid than the Fund’s Shares.
F/m Accumulator High Dividend Payers Fund | Tax Risk  
Prospectus [Line Items]  
Risk [Text Block]
Tax Risk. Because the Fund is expected to invest in the Underlying Funds, distributions of short-term capital gains by an Underlying Fund will be recognized as ordinary income by the Fund and would not be offset by the Fund’s capital loss carryforwards, if any. Capital loss carryforwards of an Underlying Fund, if any, will not be available to offset net capital gains of the Fund. Further, the Fund’s realized losses on sales of shares of an Underlying Fund may be indefinitely or permanently deferred as “wash sales” to the extent it re-acquires shares of the same Underlying Fund within the 61-day period beginning 30 days prior to the disposition date. Additionally, the Fund intends to qualify annually to be treated as a RIC under the Code.
F/m Accumulator High Dividend Payers Fund | Underlying Funds Risk  
Prospectus [Line Items]  
Risk [Text Block]
Underlying Funds Risk. The Fund’s investment in shares of Underlying Funds subjects it to the risks of owning the securities of the Underlying Fund, as well as the same structural risks faced by an investor purchasing shares of the Underlying Fund, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses. Since the Fund invests in the Underlying Funds, the Fund’s investment performance and risks are likely to be directly related to those of the Underlying Funds. The Fund’s NAV will change with changes in the value of the Underlying Funds and other assets that the Fund holds. The shares of an Underlying Fund may trade at a premium or discount to the Underlying Fund’s NAV. Investors in the Fund will indirectly bear the expenses charged by the Underlying Funds, and an investment in the Fund may entail more expenses than a direct investment in the Underlying Funds.
F/m Accumulator High Dividend Payers Fund | U.S. Government Obligations Risk  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.
F/m Accumulator High Dividend Payers Fund | Valuation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Valuation Risk. The prices provided by the Fund’s pricing services or independent dealers or the fair value determinations made by the valuation committee of the Adviser may be different from the prices used by other funds or from the prices at which securities are actually bought and sold. The prices of certain securities provided by pricing services may be subject to frequent and significant change, and will vary depending on the information that is available.
F/m Accumulator High Dividend Payers Fund | Market Capitalization Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Capitalization Risk. Securities issued by companies of different market capitalizations tend to go in and out of favor based on market and economic conditions. During a period when securities of a particular market capitalization fall behind other types of investments, the Fund’s performance could be impacted.

 

oLarge-Cap Company Risk. Large-cap companies are generally more mature and the securities issued by these companies may not be able to reach the same levels of growth as the securities issued by small- or mid-cap companies.

 

oMid-Cap Company Risk. Mid-cap companies may be more vulnerable to adverse business or economic events than larger, more established companies and the value of securities issued by these companies may move sharply.

 

oSmall-Cap Company Risk. Securities issued by small-cap companies may be riskier than those issued by larger companies, and their prices may move sharply, especially during market upturns and downturns.
F/m Accumulator High Dividend Payers Fund | Sector Risk  
Prospectus [Line Items]  
Risk [Text Block]
Sector Risk. To the extent the Fund invests more heavily in particular sectors of the economy, its performance will be especially sensitive to developments that significantly affect those sectors.

 

oFinancial Sector Risk. Financial services companies are subject to extensive government regulation and, as a result, their profitability may be affected by new regulations or regulatory interpretations. Changes in interest rates can have a disproportionate effect on the financial sector and financial services companies whose securities the Fund may purchase may themselves have concentrated portfolios, which makes them vulnerable to economic conditions that affect that sector. Financial services companies have also been affected by increased competition, which could adversely affect the profitability or viability of such companies.
F/m Accumulator High Dividend Payers Fund | Dividend Paying Stock Risk  
Prospectus [Line Items]  
Risk [Text Block]
Dividend Paying Stock Risk. Investing in dividend-paying stocks involves the risk that such stocks may fall out of favor with investors and underperform other types of stocks or the broader market. Companies that issue dividend-paying stocks are not required to pay or continue paying dividends on such stocks. It is possible that issuers of the stocks held by Fund and/or Underlying Fund(s) will not declare dividends in the future or will reduce or eliminate the payment of dividends (including reducing or eliminating anticipated accelerations or increases in the payment of dividends), which may adversely affect the Fund.
F/m Accumulator High Dividend Payers Fund | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] As a result, you may lose money on your investment in the Fund, and there can be no assurance that the Fund will achieve its investment objective.
F/m Accumulator High Dividend Payers Growth Fund | Active Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Active Management Risk. The Fund is actively managed using proprietary investment strategies and processes. There can be no guarantee that these strategies and processes will be successful or that the Fund will achieve its investment objective.
F/m Accumulator High Dividend Payers Growth Fund | Affiliated Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
Affiliated Fund Risk. Affiliated fund risk is the risk that the Adviser may select Underlying Funds and/or investments for the Fund based on its own financial interests or other business considerations rather than the Fund’s interests. The Adviser may be subject to potential conflicts of interest in selecting the Underlying Funds because affiliated Underlying Funds pay an advisory fee to the Adviser based on their assets, the fees paid to the Adviser by some affiliated Underlying Funds may be higher than those paid by other Underlying Funds or the Underlying Funds may be in need of assets to enhance their appeal to other investors, liquidity and trading and/or to enable them to carry out their investment strategies. However, the Adviser is a fiduciary to the Fund and is legally obligated to act in the Fund’s best interest when selecting Underlying Funds.
F/m Accumulator High Dividend Payers Growth Fund | Asset Class Risk  
Prospectus [Line Items]  
Risk [Text Block]
Asset Class Risk. The securities and other assets in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market, or other asset classes.
F/m Accumulator High Dividend Payers Growth Fund | Cash or Cash Equivalents Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cash or Cash Equivalents Risk. At any time, the Fund may have significant investments in cash or cash equivalents. When a substantial portion of a portfolio is held in cash or cash equivalents, there is the risk that the value of the cash account, including interest, will not keep pace with inflation, thus reducing purchasing power over time. Additionally, in rising markets, holding cash or cash equivalents may adversely affect the Fund’s performance and the Fund may not achieve its investment objectives.
F/m Accumulator High Dividend Payers Growth Fund | Concentration Risk  
Prospectus [Line Items]  
Risk [Text Block]
Concentration Risk. The Fund may be susceptible to an increased risk of loss, including losses due to adverse events that affect the Fund’s investments more than the market as a whole, to the extent that the Fund’s investments are concentrated in a particular issue, issuer or issuers, country, market segment, or asset class.
F/m Accumulator High Dividend Payers Growth Fund | Credit Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Credit Risk. The value of your investment in the Fund may change in response to changes in the credit ratings of the Fund’s portfolio securities, including with respect to Underlying Funds. Generally, investment risk and price volatility increase as a security’s credit rating declines. The financial condition of an issuer of a fixed income security held by such Fund or an Underlying Fund may cause it to default or become unable to pay interest or principal due on the security.
F/m Accumulator High Dividend Payers Growth Fund | Cyber Security Risk  
Prospectus [Line Items]  
Risk [Text Block]
Cyber Security Risk. Cyber security risk is the risk of an unauthorized breach and access to the Fund’s assets, Fund or customer data (including private shareholder information), or proprietary information, or the risk of an incident occurring that causes the Fund, the Adviser, custodian, transfer agent, distributor and other service providers and financial intermediaries to suffer data breaches, data corruption or lose operational functionality or prevent the Fund’s investors from purchasing, redeeming or exchanging Shares or receiving distributions. While the Fund and the Adviser have established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Further, the Fund cannot control the cybersecurity plans and systems of the Fund’s service providers, market makers, or issuers of securities in which the Fund invests. The Fund and the Adviser have limited ability to prevent or mitigate cyber security incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or the Adviser. Successful cyber-attacks or other cyber-failures or events affecting the Fund or its service providers may adversely impact and cause financial losses to the Fund or its shareholders. Issuers of securities in which the Fund invests are also subject to cyber security risks, and the value of these securities could decline if the issuers experience cyberattacks or other cyber-failures.
F/m Accumulator High Dividend Payers Growth Fund | Derivatives Risk  
Prospectus [Line Items]  
Risk [Text Block]
Derivatives Risk. A derivative is an instrument with a value based on the performance of an underlying currency, security, index or other reference asset. The use of derivatives involves risks different from, or greater than, the risks associated with investing in more traditional investments. Derivatives involve costs, may create leverage, and may be illiquid, volatile, and difficult to value. The Fund may not be able to close out or sell a derivative position at a particular time or at an anticipated price. The use of derivatives could also result in a loss if the counterparty to the transaction does not perform as promised, including because of such counterparty’s bankruptcy or insolvency. The investment results achieved by the use of derivatives by the Fund may not match or fully offset changes in the value of the underlying security, index or other reference asset that it was attempting to hedge or the investment opportunity the Fund was attempting to pursue.
F/m Accumulator High Dividend Payers Growth Fund | Equity Securities Risk  
Prospectus [Line Items]  
Risk [Text Block]
Equity Securities Risk. The value of the equity securities held by the Fund may fall due to general market and economic conditions, perceptions regarding the markets in which the issuers of securities held by the Fund participate, or factors relating to specific issuers in which the Fund invests. Equity securities are subordinated to preferred securities and debt in a company’s capital structure with respect to priority to a share of corporate income, and therefore will be subject to greater dividend risk than preferred securities or debt instruments. In addition, while broad market measures of equity securities have historically generated higher average returns than fixed income securities, equity securities have generally also experienced significantly more volatility in those returns.
F/m Accumulator High Dividend Payers Growth Fund | ETF Risk  
Prospectus [Line Items]  
Risk [Text Block]
ETF Risk. The Fund is an ETF, and, as a result of an ETF’s structure, it is exposed to the following risks:

 

oAuthorized Participants, Market Makers and Liquidity Providers Concentration Risk. Only an authorized participant (“AP”) may engage in creation or redemption transactions directly with the Fund. The Fund has a limited number of financial institutions that are institutional investors and may act as APs. In addition, there may be a limited number of market makers and/or liquidity providers in the marketplace. To the extent either of the following events occur, there may be significantly diminished trading in Fund Shares, Fund Shares may trade at a material discount to net asset value (“NAV”), and Fund Shares may possibly face delisting: (i) if APs exit the business or otherwise become unable to process creation and/or redemption orders and no other APs step forward to perform these services, or (ii) market makers and/or liquidity providers exit the business or significantly reduce their business activities and no other entities step forward to perform their functions. These events, among others, may lead to Fund Shares trading at a premium or discount to NAV. Thus, you may pay more (or less) than the NAV when you buy Shares of the Fund in the secondary market, and you may receive less (or more) than NAV when you sell those Shares in the secondary market. A diminished market for an ETF’s shares substantially increases the risk that a shareholder may pay considerably more or receive significantly less than the underlying value of the ETF shares bought or sold. In periods of market volatility, APs, market makers and/or liquidity providers may be less willing to transact in Fund Shares.

 

oSecondary Market Trading Risk. Although Shares are intended to be listed on a national securities exchange, The Nasdaq Stock Market LLC (the “Exchange”), and may be traded on U.S. exchanges other than the Exchange, there can be no assurance that an active or liquid trading market for them will develop or be maintained. In addition, trading in Shares on the Exchange may be halted. During periods of market stress, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines.

 

oShares May Trade at Prices Other Than NAV Risk. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. As with all ETFs, Shares may be bought and sold in the secondary market at market prices. Shares trade on a stock exchange at prices at, above, or below the Fund’s most recent NAV. The Fund’s NAV is calculated at the end of each business day and fluctuates with changes in the market value of the Fund’s holdings. The trading price of the Shares fluctuates continuously throughout trading hours on the exchange, based on both the relative market supply of, and demand for, the Shares and the underlying value of the Fund’s portfolio holdings. As a result, the trading prices of the Shares may deviate from the Fund’s NAV. Although it is expected that the market price of Shares will approximate the Fund’s NAV, there may be times when the market price of Shares is more than the NAV intra-day (premium) or less than the NAV intra-day (discount). This risk is heightened in times of market volatility or periods of steep market declines. Any of these factors, among others, may lead to the Shares trading at a premium or discount to NAV.

 

To the extent the Fund invests in Underlying Funds, which are also ETFs, the Fund will be further exposed to the above ETF risks.

F/m Accumulator High Dividend Payers Growth Fund | Futures Risk  
Prospectus [Line Items]  
Risk [Text Block]
Futures Risk. Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the Adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.
F/m Accumulator High Dividend Payers Growth Fund | High Portfolio Turnover Risk  
Prospectus [Line Items]  
Risk [Text Block]
High Portfolio Turnover Risk. Active and frequent trading of the Fund’s portfolio securities may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs, which could reduce the Fund’s return.
F/m Accumulator High Dividend Payers Growth Fund | Income Risk  
Prospectus [Line Items]  
Risk [Text Block]
Income Risk. Under certain market conditions, the Fund may invest in Underlying Funds that are subject to income risk. The Fund’s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.
F/m Accumulator High Dividend Payers Growth Fund | Inflation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Inflation Risk. Under certain market conditions, the Fund may invest in an Underlying Fund that is subject to inflation risk. Inflation risk is the risk that the value of assets or income from investments will be less in the future as inflation decreases the value of money. As inflation increases, the present value of the Fund’s assets may decline.
F/m Accumulator High Dividend Payers Growth Fund | Interest Rate Risk [Member]  
Prospectus [Line Items]  
Risk [Text Block]
Interest-Rate Risk. Interest rate risk is the risk of losses attributable to changes in interest rates. In general, if prevailing interest rates rise, the values of debt instruments tend to fall, and if interest rates fall, the values of debt instruments tend to rise. Changes in the value of a debt instrument usually will not affect the amount of income the Fund receives from it but will generally affect the value of your investment in the Fund. Changes in interest rates may also affect the liquidity of the Fund’s investments in debt instruments. In general, the longer the maturity or duration of a debt instrument, the greater its sensitivity to changes in interest rates. The Fund is subject to the risk that the income generated by its investments may not keep pace with inflation. Actions by governments and central banking authorities can result in increases or decreases in interest rates, which may negatively affect the value of debt instruments held by the Fund and have a negative impact on the Fund’s performance and NAV. Rising interest rates may prompt redemptions from the Fund, which may force the Fund to sell investments at a time when it is not advantageous to do so, which could result in losses. During periods of very low or negative interest rates, the Fund may be unable to maintain positive returns or pay dividends to Fund shareholders. Very low or negative interest rates may magnify interest rate risk. Changing interest rates, including rates that fall below zero, may have unpredictable effects on markets, result in heightened market volatility and detract from the Fund’s performance to the extent the Fund is exposed to such interest rates. Additionally, under certain market conditions in which interest rates are low and the market prices for portfolio securities have increased, the Fund may have a very low or even negative yield. A low or negative yield would cause the Fund to lose money in certain conditions and over certain time periods. An increase in interest rates will generally cause the value of securities held by the Fund to decline, may lead to heightened volatility in the fixed-income markets and may adversely affect the liquidity of certain fixed-income investments, including those held by the Fund. The historically low-interest rate environment in recent years heightens the risks associated with rising interest rates.
F/m Accumulator High Dividend Payers Growth Fund | Issuer Risk  
Prospectus [Line Items]  
Risk [Text Block]
Issuer Risk. The performance of the Fund’s investment in Underlying Funds depends on the performance of individual securities or other assets to which the Underlying Fund has exposure. The value of securities or other assets may decline, or perform differently from the market as a whole, due to changes in the financial condition or credit rating of the issuer or counterparty.
F/m Accumulator High Dividend Payers Growth Fund | Liquidity Risk  
Prospectus [Line Items]  
Risk [Text Block]
Liquidity Risk. Certain securities held by an Underlying Fund may be difficult (or impossible) to sell at the time and at the price the Adviser would like. As a result, an Underlying Fund may have to hold these securities longer than it would like and may forego other investment opportunities. There is the possibility that an Underlying Fund may lose money or be prevented from realizing capital gains if it cannot sell a security at a particular time and price.
F/m Accumulator High Dividend Payers Growth Fund | Management Risk  
Prospectus [Line Items]  
Risk [Text Block]
Management Risk. The Fund is subject to management risk, which is the risk that the Adviser’s analysis of economic conditions and expectations regarding interest rate changes may fail to produce the intended results. In other words, the individual investments of the Fund may not perform as well as expected, and/or the Fund’s portfolio management practices may not work to achieve their desired result.
F/m Accumulator High Dividend Payers Growth Fund | Market Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Risk. Economies and financial markets throughout the world are becoming increasingly interconnected, which increases the likelihood that events or conditions in one country or region will adversely impact markets or issuers in other countries or regions. The value of the Fund and/or the Underlying Fund’s investments may be negatively affected by adverse changes in overall economic or market conditions, such as the level of economic activity and productivity, unemployment and labor force participation rates, inflation or deflation (and expectations for inflation or deflation), interest rates, demand and supply for particular products or resources including labor, and debt levels and credit ratings, among other factors. Such adverse conditions may contribute to an overall economic contraction across entire economies or markets, which may negatively impact the profitability of issuers operating in those economies or markets. The Fund and the Underlying Funds are subject to the risk that geopolitical events will disrupt securities markets and adversely affect global economies and markets. The Fund’s and the Underlying Funds’ NAVs and market prices may fluctuate significantly in response to these and other factors including economic, political, or financial events, public health crises (such as epidemics or pandemics), or other disruptive events (whether real, expected or perceived) in the U.S. and global markets. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. As a result, an investor could lose money over short or long periods of time.
F/m Accumulator High Dividend Payers Growth Fund | Market Price Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Price Risk. Fund Shares are listed for trading on an exchange and are bought and sold in the secondary market at market prices. The market prices of Shares will fluctuate, in some cases materially, in response to changes in the NAV and supply and demand for Shares. As a result, the trading prices of Shares may deviate significantly from the NAV during periods of market volatility. The Adviser cannot predict whether Shares will trade above, below or at their NAV. Given the fact that Shares can be created and redeemed in Creation Units (defined below), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained in the long term. If market makers exit the business or are unable to continue making markets in Fund Shares, Shares may trade at a discount to NAV like closed-end fund shares and may even face delisting (that is, investors would no longer be able to trade Shares in the secondary market). Further, while the creation/redemption feature is designed to make it likely that Shares normally will trade close to the value of the Fund’s holdings, disruptions to creations and redemptions, including disruptions at market makers, APs or market participants, or during periods of significant market volatility, may result in market prices that differ significantly from the value of the Fund’s holdings. Although market makers will generally take advantage of differences between the NAV and the market price of Fund Shares through arbitrage opportunities, there is no guarantee that they will do so. In addition, the securities held by the Fund may be traded in markets that close at a different time than the exchange on which the Fund’s Shares trade. Liquidity in those securities may be reduced after the applicable closing times. Accordingly, during the time when the exchange is open but after the applicable market closing, fixing or settlement times, bid-ask spreads and the resulting premium or discount to the Shares’ NAV are likely to widen. Further, secondary markets may be subject to irregular trading activity, wide bid-ask spreads and extended trade settlement periods, which could cause a material decline in the Fund’s NAV. The Fund’s investment results are measured based upon the daily NAV of the Fund. Investors purchasing and selling Shares in the secondary market may not experience investment results consistent with those experienced by those APs creating and redeeming Shares directly with the Fund.
F/m Accumulator High Dividend Payers Growth Fund | Market Trading Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund Shares (including through a trading halt), losses from trading in secondary markets, periods of high volatility, and disruptions in the process of creating and redeeming Fund Shares. Any of these factors, among others, may lead to the Fund’s Shares trading in the secondary market at a premium or discount to NAV or to the intraday value of the Fund’s portfolio holdings. If you buy Fund Shares at a time when the market price is at a premium to NAV or sell Fund Shares at a time when the market price is at a discount to NAV, you may pay significantly more or receive significantly less than the underlying value of the Fund Shares.
F/m Accumulator High Dividend Payers Growth Fund | New Fund Risk  
Prospectus [Line Items]  
Risk [Text Block]
New Fund Risk. The Fund is a newly-organized management investment company with a limited operating history. In addition, there can be no assurance that the Fund will grow to, or maintain, an economically viable size, in which case the Board of Directors (the “Board”) of The RBB Fund, Inc. (the “Company”) may determine to liquidate the Fund.
F/m Accumulator High Dividend Payers Growth Fund | Operational Risk  
Prospectus [Line Items]  
Risk [Text Block]
Operational Risk. The Fund is exposed to operational risks arising from a number of factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties, or other third parties, failed or inadequate processes and technology or systems failures. The Fund and the Adviser seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address significant operational risks.
F/m Accumulator High Dividend Payers Growth Fund | Options Risk  
Prospectus [Line Items]  
Risk [Text Block]
Options Risk. If the Fund purchases a call option, it receives, in return for the premium it pays, the right to buy from the writer of the option the underlying security at a specified price at any time before the option expires. The Fund purchases call options in anticipation of an increase in the market value of securities that it intends ultimately to buy. During the life of the call option, the Fund is able to buy the underlying security at the exercise price regardless of any increase in the market price of the underlying security. In order for a call option to result in a gain, the market price of the underlying security must exceed the sum of the exercise price, the premium paid, and transaction costs.
F/m Accumulator High Dividend Payers Growth Fund | Premium/Discount Risk  
Prospectus [Line Items]  
Risk [Text Block]
Premium/Discount Risk. The market price of the Fund’s Shares will generally fluctuate in accordance with changes in the Fund’s NAV as well as the relative supply of and demand for Shares on the Exchange. The Adviser cannot predict whether Shares will trade below, at, or above their NAV because the Shares trade on the Exchange at market prices and not at NAV. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for Shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that Shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their NAV), the Adviser believes that large discounts or premiums to the NAV of Shares should not be sustained. During stressed market conditions, the market for the Fund’s Shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying holdings, which could in turn lead to differences between the market price of the Fund’s Shares and their NAV and the bid/ask spread on the Fund’s Shares may widen.
F/m Accumulator High Dividend Payers Growth Fund | Pricing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Pricing Risk. If market conditions make it difficult to value some investments, the Fund may value these investments using more subjective methods, such as fair value pricing. In such cases, the value determined for an investment could be different from the value realized upon such investment’s sale. As a result, you could pay more than the market value when buying Fund Shares or receive less than the market value when selling Fund Shares.
F/m Accumulator High Dividend Payers Growth Fund | Rating Agencies Risk  
Prospectus [Line Items]  
Risk [Text Block]
Rating Agencies Risk. Ratings are not an absolute standard of quality, but rather general indicators that reflect only the view of the originating rating agencies from which an explanation of the significance of such ratings may be obtained. There is no assurance that a particular rating will continue for any given period of time or that any such rating will not be revised downward or withdrawn entirely if, in the judgment of the agency establishing the rating, circumstances so warrant. A downward revision or withdrawal of such ratings, or either of them, may have an effect on the liquidity or market price of the securities in which an Underlying Fund invests.
F/m Accumulator High Dividend Payers Growth Fund | Reinvestment Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reinvestment Risk. Reinvestment risk is the risk that the Fund’s portfolio will decline if and when the Fund reinvests the proceeds from the disposition of its portfolio securities at market interest rates that are below the portfolio’s current earnings rate. A decline in income could negatively affect the market price of the Shares.
F/m Accumulator High Dividend Payers Growth Fund | Reverse Repurchase Agreements Risk  
Prospectus [Line Items]  
Risk [Text Block]
Reverse Repurchase Agreements Risk. Reverse repurchase agreements are a form of secured borrowing and subject the Fund to the risks associated with leverage, including exposure to potential gains and losses in excess of the amount invested, resulting in an increase in the speculative character of the Fund’s outstanding Shares. Reverse repurchase agreements involve the risk that the investment return earned by the Fund (from the investment of the proceeds) will be less than the interest expense of the transaction, that the market value of the securities sold by the Fund will decline below the price the Fund is obligated to pay to repurchase the securities, and that the other party may fail to return the securities in a timely manner or at all.
F/m Accumulator High Dividend Payers Growth Fund | Risk of Investing in the U.S.  
Prospectus [Line Items]  
Risk [Text Block]
Risk of Investing in the U.S. Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.
F/m Accumulator High Dividend Payers Growth Fund | Securities Lending Risk  
Prospectus [Line Items]  
Risk [Text Block]
Securities Lending Risk. The Fund may engage in securities lending (i.e., lend portfolio securities to institutions, such as certain broker-dealers). Securities lending involves the risk that the Fund may lose money because the borrower of the loaned securities fails to return the securities in a timely manner or at all. The Fund could also lose money in the event of a decline in the value of collateral provided for loaned securities or a decline in the value of any investment made with cash collateral. These events could also trigger adverse tax consequences for the Fund. The Fund could also experience a loss or delay in the recovery of its securities if the borrowing institution breaches its agreement with the Fund.
F/m Accumulator High Dividend Payers Growth Fund | Swaps Risk  
Prospectus [Line Items]  
Risk [Text Block]
Swaps Risk. The Fund will invest in swap agreements, which may be less liquid than other types of investments. The illiquidity of swap agreements could have a negative effect on the Fund’s ability to achieve its investment objective and may result in losses to Fund shareholders. In stressed market conditions, the liquidity of the Fund’s Shares may begin to mirror those of the underlying portfolio holdings, which can be significantly less liquid than the Fund’s Shares.
F/m Accumulator High Dividend Payers Growth Fund | Tax Risk  
Prospectus [Line Items]  
Risk [Text Block]
Tax Risk. Because the Fund is expected to invest in the Underlying Funds, distributions of short-term capital gains by an Underlying Fund will be recognized as ordinary income by the Fund and would not be offset by the Fund’s capital loss carryforwards, if any. Capital loss carryforwards of an Underlying Fund, if any, will not be available to offset net capital gains of the Fund. Further, the Fund’s realized losses on sales of shares of an Underlying Fund may be indefinitely or permanently deferred as “wash sales” to the extent it re-acquires shares of the same Underlying Fund within the 61-day period beginning 30 days prior to the disposition date.
F/m Accumulator High Dividend Payers Growth Fund | Underlying Funds Risk  
Prospectus [Line Items]  
Risk [Text Block]
Underlying Funds Risk. The Fund’s investment in shares of Underlying Funds subjects it to the risks of owning the securities of the Underlying Fund, as well as the same structural risks faced by an investor purchasing shares of the Underlying Fund, including authorized participant concentration risk, market maker risk, premium/discount risk and trading issues risk. As a shareholder in another ETF, the Fund bears its proportionate share of the ETF’s expenses, subjecting Fund shareholders to duplicative expenses. Since the Fund invests in the Underlying Funds, the Fund’s investment performance and risks are likely to be directly related to those of the Underlying Funds. The Fund’s NAV will change with changes in the value of the Underlying Funds and other assets that the Fund holds. The shares of an Underlying Fund may trade at a premium or discount to the Underlying Fund’s NAV. Investors in the Fund will indirectly bear the expenses charged by the Underlying Funds, and an investment in the Fund may entail more expenses than a direct investment in the Underlying Funds.
F/m Accumulator High Dividend Payers Growth Fund | U.S. Government Obligations Risk  
Prospectus [Line Items]  
Risk [Text Block]
U.S. Government Obligations Risk. While U.S. Treasury obligations are backed by the “full faith and credit” of the U.S. Government, such securities are nonetheless subject to credit risk (i.e., the risk that the U.S. Government may be, or be perceived to be, unable or unwilling to honor its financial obligations, such as making payments). Securities issued or guaranteed by federal agencies or authorities and U.S. Government-sponsored instrumentalities or enterprises may or may not be backed by the full faith and credit of the U.S. Government. U.S. Treasury obligations may differ from other securities in their interest rates, maturities, times of issuance and other characteristics and may provide relatively lower returns than those of other securities. Similar to other issuers, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s U.S. Treasury obligations to decline.
F/m Accumulator High Dividend Payers Growth Fund | Valuation Risk  
Prospectus [Line Items]  
Risk [Text Block]
Valuation Risk. The prices provided by the Fund’s pricing services or independent dealers or the fair value determinations made by the valuation committee of the Adviser may be different from the prices used by other funds or from the prices at which securities are actually bought and sold. The prices of certain securities provided by pricing services may be subject to frequent and significant change, and will vary depending on the information that is available.
F/m Accumulator High Dividend Payers Growth Fund | Market Capitalization Risk  
Prospectus [Line Items]  
Risk [Text Block]
Market Capitalization Risk. Securities issued by companies of different market capitalizations tend to go in and out of favor based on market and economic conditions. During a period when securities of a particular market capitalization fall behind other types of investments, the Fund’s performance could be impacted.

 

oLarge-Cap Company Risk. Large-cap companies are generally more mature and the securities issued by these companies may not be able to reach the same levels of growth as the securities issued by small- or mid-cap companies.

 

oMid-Cap Company Risk. Mid-cap companies may be more vulnerable to adverse business or economic events than larger, more established companies and the value of securities issued by these companies may move sharply.

 

oSmall-Cap Company Risk. Securities issued by small-cap companies may be riskier than those issued by larger companies, and their prices may move sharply, especially during market upturns and downturns.
F/m Accumulator High Dividend Payers Growth Fund | Sector Risk  
Prospectus [Line Items]  
Risk [Text Block]
Sector Risk. To the extent the Fund invests more heavily in particular sectors of the economy, its performance will be especially sensitive to developments that significantly affect those sectors.

 

oFinancial Sector Risk. Financial services companies are subject to extensive government regulation and, as a result, their profitability may be affected by new regulations or regulatory interpretations. Changes in interest rates can have a disproportionate effect on the financial sector and financial services companies whose securities the Fund may purchase may themselves have concentrated portfolios, which makes them vulnerable to economic conditions that affect that sector. Financial services companies have also been affected by increased competition, which could adversely affect the profitability or viability of such companies.
F/m Accumulator High Dividend Payers Growth Fund | Dividend Paying Stock Risk  
Prospectus [Line Items]  
Risk [Text Block]
Dividend Paying Stock Risk. Investing in dividend-paying stocks involves the risk that such stocks may fall out of favor with investors and underperform other types of stocks or the broader market. Companies that issue dividend-paying stocks are not required to pay or continue paying dividends on such stocks. It is possible that issuers of the stocks held by Fund and/or Underlying Fund(s) will not declare dividends in the future or will reduce or eliminate the payment of dividends (including reducing or eliminating anticipated accelerations or increases in the payment of dividends), which may adversely affect the Fund.
F/m Accumulator High Dividend Payers Growth Fund | Growth Investing Risk  
Prospectus [Line Items]  
Risk [Text Block]
Growth Investing Risk. Growth stocks, as a group, may be out of favor with the market and underperform value stocks or the overall equity market. Growth stocks are generally more sensitive to market movements than other types of stocks, primarily because their prices are based heavily on the future expectations of the economy and the stock’s issuing company.
F/m Accumulator High Dividend Payers Growth Fund | Risk Lose Money [Member]  
Prospectus [Line Items]  
Risk [Text Block] As a result, you may lose money on your investment in the Fund, and there can be no assurance that the Fund will achieve its investment objective.