You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the tables and examples below.

Expense Example [Heading]

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Example.

Strategy [Heading]

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Principal Investment Strategies

Strategy Portfolio Concentration [Text]

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Industry Concentration Policy. The Fund will concentrate its investments (i.e., hold 25% or more of its total assets) in a particular industry or group of industries to approximately the same extent that the Underlying Index is concentrated. For purposes of this limitation, securities of the U.S. government (including its agencies and instrumentalities), repurchase agreements collateralized by U.S. government securities, and securities of state or municipal governments and their political subdivisions are not considered to be issued by members of any industry.

Risk Narrative [Text Block]

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As with any investment, you could lose all or part of your investment in the Fund, and the Fund's performance could trail that of other investments. The Fund is subject to certain risks, including the principal risks noted below, any of which may adversely affect the Fund's net asset value per share (“NAV”), trading price, yield, total return and ability to meet its investment objective. The order of the below risk factors does not indicate the significance of any particular risk factor.

Asset Class Risk. Securities and other assets in the Underlying Index or in the Fund's portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes.

Assets Under Management (AUM) Risk. From time to time, an Authorized Participant (as defined in the Creations and Redemptions section of the Prospectus), a third-party investor, the Fund’s adviser or an affiliate of the Fund’s adviser, or a fund may invest in the Fund and hold its investment for a specific period of time to allow the Fund to achieve size or scale. There can be no assurance that any such entity would not redeem its investment or that the size of the Fund would be maintained at such levels, which could negatively impact the Fund.

Authorized Participant Concentration Risk. Only an Authorized Participant may engage in creation or redemption transactions directly with the Fund, and none of those Authorized Participants is obligated to engage in creation and/or redemption transactions. The Fund has a limited number of institutions that may act as Authorized Participants on an agency basis (i.e., on behalf of other market participants). To the extent that Authorized Participants exit the business or are unable to proceed with creation or redemption orders with respect to the Fund and no other Authorized Participant is able to step forward to create or redeem, Fund shares may be more likely to trade at a premium or discount to NAV and possibly face trading halts or delisting.

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 the securities and/or other assets of a particular issuer or issuers, country, group of countries, region, market, industry, group of industries, sector or asset class.

Cybersecurity Risk. Failures or breaches of the electronic systems of the Fund, the Fund's adviser, distributor, the Index Provider and other service providers, market makers, Authorized Participants or the issuers of securities in which the Fund invests have the ability to cause disruptions, negatively impact the Fund’s business operations and/or potentially result in financial losses to the Fund and its shareholders. While the Fund has established business continuity plans and risk management systems seeking to address system breaches or failures, there are inherent limitations in such plans and systems. Furthermore, the Fund cannot control the cybersecurity plans and systems of the Fund’s Index Provider and other service providers, market makers, Authorized Participants or issuers of securities in which the Fund invests.

Declining Yield Risk. During the six months prior to the Fund’s planned termination date, the Fund’s yield will generally tend to move toward prevailing money market rates and may be lower than the yields of the bonds previously held by the Fund and lower than prevailing yields for bonds in the market.

Income Risk. The Fund's income may decline if interest rates fall. This decline in income can occur because the Fund may subsequently invest in lower-yielding bonds as bonds in its portfolio mature, are near maturity, or bonds in the Underlying Index are substituted, or the Fund otherwise needs to purchase additional bonds. As the Fund does not seek to return any predetermined amount at maturity or in periodic distributions, the amount of income generated by the Fund may vary during its term. In addition, the Fund's income is expected to decline in the months leading up to its maturity date because its portfolio will increasingly consist of cash and cash equivalents.

Index-Related Risk. There is no guarantee that the Fund’s investment results will have a high degree of correlation to those of the Underlying Index or that the Fund will achieve its investment objective. Market disruptions and regulatory restrictions could have an adverse effect on the Fund’s ability to adjust its exposure to the required levels in order to track the Underlying Index. Errors in index data, index computations or the construction of the Underlying Index in accordance with its methodology may occur from time to time and may not be identified and corrected by the Index Provider for a period of time or at all, which may have an adverse impact on the Fund and its shareholders. Unusual market conditions may cause the Index Provider to postpone a scheduled rebalance, which could cause the Underlying Index to vary from its normal or expected composition.

Infectious Illness Risk. An outbreak of an infectious respiratory illness, COVID-19, caused by a novel coronavirus has resulted in travel restrictions, disruption of healthcare systems, prolonged quarantines, cancellations, supply chain disruptions, lower consumer demand, layoffs, ratings downgrades, defaults and other significant economic impacts. Certain markets have experienced temporary closures, extreme volatility, severe losses, reduced liquidity and increased trading costs. These events will have an impact on the Fund and its investments and could impact the Fund’s ability to purchase or sell securities or cause elevated tracking error and increased premiums or discounts to the Fund’s NAV. Other infectious illness outbreaks in the future may result in similar impacts.

Interest Rate Risk. 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 heightens the risks associated with rising interest rates.

Issuer Risk. The performance of the Fund depends on the performance of individual securities to which the Fund has exposure. The Fund may be adversely affected if an issuer of underlying securities held by the Fund is unable or unwilling to repay principal or interest when due.

Management Risk. As the Fund will not fully replicate the Underlying Index, it is subject to the risk that BFA's investment strategy may not produce the intended results.

Market Risk. The Fund could lose money over short periods due to short-term market movements and over longer periods during more prolonged market downturns. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issue, recessions, or other events could have a significant impact on the Fund and its investments and could result in increased premiums or discounts to the Fund’s NAV.

Market Trading Risk. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares, losses from trading in secondary markets, periods of high volatility and disruptions in the creation/redemption process. ANY OF THESE FACTORS, AMONG OTHERS, MAY LEAD TO THE FUND'S SHARES TRADING AT A PREMIUM OR DISCOUNT TO NAV.

Non-Diversification Risk. The Fund may invest a large percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund's performance may depend on the performance of a small number of issuers.

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 BFA 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.

Passive Investment Risk. The Fund is not actively managed, and BFA generally does not attempt to take defensive positions under any market conditions, including declining markets.

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.

Securities Lending Risk. The Fund may engage in securities lending. 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 investments made with cash collateral. These events could also trigger adverse tax consequences for the Fund.

Small Fund Risk. When the Fund’s size is small, the Fund may experience low trading volume and wide bid/ask spreads. In addition, the Fund may face the risk of being delisted if the Fund does not meet certain conditions of the listing exchange. Any resulting liquidation of the Fund could cause the Fund to incur elevated transaction costs for the Fund and negative tax consequences for its shareholders.

Tracking Error Risk. The Fund may be subject to tracking error, which is the divergence of the Fund’s performance from that of the Underlying Index. Tracking error may occur because of differences between the securities and other instruments held in the Fund’s portfolio and those included in the Underlying Index, pricing differences, transaction costs incurred by the Fund, the Fund’s holding of uninvested cash, differences in timing of the accrual of or the valuation of distributions, the requirements to maintain pass-through tax treatment, portfolio transactions carried out to minimize the distribution of capital gains to shareholders, acceptance of custom baskets, changes to the Underlying Index or the costs to the Fund of complying with various new or existing regulatory requirements. This risk may be heightened during times of increased market volatility or other unusual market conditions. Tracking error also may result because the Fund incurs fees and expenses, while the Underlying Index does not. BFA EXPECTS THAT THE FUND MAY EXPERIENCE HIGHER TRACKING ERROR THAN IS TYPICAL FOR SIMILAR INDEX ETFs.

U.S. Treasury Obligations Risk. 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.

Risk Nondiversified Status [Text]

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Non-Diversification Risk. The Fund may invest a large percentage of its assets in securities issued by or representing a small number of issuers. As a result, the Fund's performance may depend on the performance of a small number of issuers.

Performance Narrative [Text Block]

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As of the date of the Prospectus, the Fund has been in operation for less than one full calendar year and therefore does not report its performance information.

Management Fees

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0.07%

Other Expenses

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none

^[1]

Total Annual Fund Operating Expenses

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0.07%

Total Annual Fund Operating Expenses After Fee Waivers

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0.07%

3 Years

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$ 23