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      id="bf9e8e05-8349-4fe0-99c4-eb5a9fc52cb1">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;font-weight:bold;"&gt;Example&lt;/span&gt;</oef:ExpenseExampleHeading>
    <oef:ExpenseExampleNoRedemptionNarrativeTextBlock
      contextRef="S000053970"
      id="x_5dbd424e-e7c6-4204-9d73-24ac99e651ce">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;The example assumes that you invest $10,000 in the Fund for the time periods indicated and then hold or sell all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund&#x2019;s operating expenses remain at current levels. Although your actual costs may be higher or lower, based on these &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;assumptions your costs would be:&lt;/span&gt;</oef:ExpenseExampleNoRedemptionNarrativeTextBlock>
    <oef:ExpenseExampleNoRedemptionYear01
      contextRef="S000053970_C000169822"
      decimals="INF"
      id="x_089b3116-d105-4c39-92f4-f429d1e57de6"
      unitRef="USD">50</oef:ExpenseExampleNoRedemptionYear01>
    <oef:ExpenseExampleNoRedemptionYear03
      contextRef="S000053970_C000169822"
      decimals="INF"
      id="x_028ff749-f1e1-4c27-b4f0-9131c8d86bc8"
      unitRef="USD">157</oef:ExpenseExampleNoRedemptionYear03>
    <oef:ExpenseExampleNoRedemptionYear05
      contextRef="S000053970_C000169822"
      decimals="INF"
      id="b7fa1d1e-f61e-4114-9270-19b897d6ec34"
      unitRef="USD">274</oef:ExpenseExampleNoRedemptionYear05>
    <oef:ExpenseExampleNoRedemptionYear10
      contextRef="S000053970_C000169822"
      decimals="INF"
      id="x_9fe1430c-a27e-45ab-a846-d06c16a73843"
      unitRef="USD">616</oef:ExpenseExampleNoRedemptionYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="S000053970"
      id="b8936620-9cff-495b-a528-bb90158d2485">&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;Portfolio Turnover&lt;/span&gt;</oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="S000053970"
      id="e9386e50-01d5-4048-9529-07a5ae7707ed">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;The Fund pays transaction costs, such as commissions, when it buys and sells securities (or &#x201c;turns over&#x201d; its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund&#x2019;s performance. During the most recent fiscal year the Fund&#x2019;s portfolio turnover rate was &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;33%&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; of the average value of its portfolio. &lt;/span&gt;</oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="S000053970"
      decimals="4"
      id="d04cbefb-921b-4646-b73c-ddff15fc51af"
      unitRef="pure">0.33</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="S000053970"
      id="x_4d930348-bbc8-421f-be22-7284e225b256">&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;Principal Investment Strategies&lt;/span&gt;</oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="S000053970"
      id="x_4d8fc006-5eb0-41bd-bb86-e9634413ae4a">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Under normal market conditions, the Fund seeks to achieve its investment objective by investing at least 80% of its net assets (plus any investment borrowings) in municipal debt securities that pay interest that is exempt from regular federal income taxes. Municipal debt securities are generally issued by or on behalf of states, territories or possessions of the United States and the District of Columbia and their political subdivisions, agencies, authorities and other instrumentalities. The Fund may invest in a range of municipal securities, including, but not limited to, municipal lease obligations (and certificates of participation in such obligations), municipal general obligation bonds, municipal revenue bonds, municipal notes, municipal cash equivalents, private activity bonds (including without limitation industrial development bonds), and pre-refunded and escrowed to maturity bonds. In addition, the Fund may invest in inverse floating rate securities issued by tender option bond (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;&#x201c;TOB&#x201d;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;) trusts and &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;securities issued by custodial receipt trusts, each of which are investment vehicles the underlying assets of which are municipal &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;bonds. The Fund may invest without limitation in municipal securities that pay interest and generate income subject to federal &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;and state alternative minimum tax.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;The Fund may invest in municipal debt securities of any duration, maturity or credit quality, but will focus on longer duration, higher yielding municipal debt securities, including municipal debt securities that are rated below investment grade by at least one nationally recognized statistical rating organization (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;&#x201c;NRSRO&#x201d;&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;) rating such securities, or if unrated, determined by the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Fund's investment advisor, First Trust Advisors L.P. (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;"First Trust"&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; or the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;"Advisor"&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;) to be of comparable quality, also known as &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;&#x201c;junk&#x201d; bonds. Additionally, for newly-issued municipal debt securities, the Advisor may consider an expected rating provided by an NRSRO as if it were a final rating. The Fund may invest up to 10% of its net assets in municipal debt securities that are currently in default (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;"Distressed Securities"&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;). If, subsequent to purchase by the Fund, a municipal debt security held by the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Fund goes into default, the Fund may continue to hold the security and it will not cause the Fund to violate the 10% investment limitation; however, the defaulted municipal debt security will be taken into account for purposes of determining whether &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;purchases of additional municipal debt securities will cause the Fund to violate its limitation on holding Distressed Securities.&lt;/span&gt;</oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_RiskLoseMoneyMember"
      id="x_245160bb-da3c-4052-8e61-9c6166da3596">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;You could lose money by investing in the Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_RiskNotInsuredDepositoryInstitutionMember"
      id="x_88623902-c6de-4d99-9018-d4b75afca9ad">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;An investment in the Fund is not a deposit of a bank and is not insured or &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_AlternativeMinimumTaxRiskMember"
      id="x_483d1a29-ea66-4637-a603-fbd42bde5f5f">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;ALTERNATIVE MINIMUM TAX RISK. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;Although the interest received from municipal securities is generally exempt from federal &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;income tax, the Fund may invest in municipal securities subject to the federal alternative minimum tax on individuals. For tax years beginning after December 31, 2022, interest on the bonds may affect the corporate alternative minimum tax for certain corporations. Accordingly, investment in the Fund could cause shareholders to be subject to the federal alternative minimum &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;tax.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_AuthorizedParticipantConcentrationRiskMember"
      id="x_6fe404dd-f8d0-45e8-9557-b7a6ca8401f1">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;AUTHORIZED PARTICIPANT CONCENTRATION RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Only an authorized participant may engage in creation or redemption &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;transactions directly with the Fund. A limited number of institutions act as authorized participants for the Fund. To the extent that these institutions exit the business or are unable to proceed with creation and/or redemption orders and no other authorized participant steps forward to create or redeem, the Fund&#x2019;s shares may trade at a premium or discount (the difference between the market price of the Fund's shares and the Fund's net asset value) and possibly face delisting and the bid/ask spread (the difference between the price that someone is willing to pay for shares of the Fund at a specific point in time versus &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;the price at which someone is willing to sell) on the Fund&#x2019;s shares may widen.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CallRiskMember"
      id="x_67a5ae52-9f60-4968-bace-09b47e0f08ad">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CALL RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Some debt securities may be redeemed, or &#x201c;called,&#x201d; at the option of the issuer before their stated maturity date. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;In general, an issuer will call its debt securities if they can be refinanced by issuing new debt securities which bear a lower interest rate. The Fund is subject to the possibility that during periods of falling interest rates an issuer will call its high yielding debt securities. The Fund would then be forced to invest the proceeds at lower interest rates, likely resulting in a decline in &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;the Fund&#x2019;s income.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CashTransactionsRiskMember"
      id="x_0b9dd97d-f408-4bfd-8555-6f3ecff3b35c">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CASH TRANSACTIONS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund will effect some or all of its creations and redemptions for cash rather than in-kind. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;As a result, an investment in the Fund may be less tax-efficient than an investment in an ETF that effects all of its creations and redemptions in-kind. Because the Fund may effect redemptions for cash, it may be required to sell portfolio securities in order to obtain the cash needed to distribute redemption proceeds. A sale of portfolio securities may result in capital gains &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;or losses and may also result in higher brokerage costs.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CounterpartyRiskMember"
      id="x_8d812bb9-a5f6-4b51-8d6d-b7418342cd63">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;COUNTERPARTY RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Fund transactions involving a counterparty are subject to the risk that the counterparty will not fulfill &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;its obligation to the Fund. Counterparty risk may arise because of the counterparty&#x2019;s financial condition (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;i.e.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;, financial difficulties, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;bankruptcy, or insolvency), market activities and developments, or other reasons, whether foreseen or not. A counterparty&#x2019;s inability to fulfill its obligation may result in significant financial loss to the Fund. The Fund may be unable to recover its &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;investment from the counterparty or may obtain a limited recovery, and/or recovery may be delayed.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CreditRatingAgencyRiskMember"
      id="x_607e03b1-c8f8-4ab7-81d6-f4bd637d1f85">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CREDIT RATING AGENCY RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Credit ratings are determined by credit rating agencies such as S&amp;amp;P Global Ratings, Moody&#x2019;s &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Investors Services, Inc. and Fitch Inc., and are only the opinions of such entities. Ratings assigned by a rating agency are not absolute standards of credit quality and do not evaluate market risk or the liquidity of securities. First Trust makes no warranty whatsoever regarding the ability of such ratings to accurately reflect the creditworthiness of an issuer. Any shortcomings, changes to or inefficiencies in credit rating agencies&#x2019; processes for determining credit ratings may adversely affect the credit &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;ratings of securities held by the Fund or securities in which the Fund would otherwise invest and, as a result, may adversely &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;affect those securities&#x2019; perceived or actual credit risk, as well as the Fund&#x2019;s performance.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CreditRiskMember"
      id="a0b1dbc5-645b-49cf-81d3-631b40b150e3">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CREDIT RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; An issuer or other obligated party of a debt security may be unable or unwilling to make dividend, interest &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and/or principal payments when due. In addition, the value of a debt security may decline because of concerns about the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;issuer&#x2019;s ability or unwillingness to make such payments.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CreditSpreadRiskMember"
      id="x_649bf5e9-f580-4ee4-bb0f-7ac43960ecd3">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CREDIT SPREAD RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; From time to time, spreads (&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;i.e.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;, the difference in yield between debt securities that have different &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;credit qualities or other differences) may increase, which may reduce the market value of some of the Fund&#x2019;s debt securities. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;While the Fund may employ strategies to mitigate credit spread risk, these strategies may not be successful.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CurrentMarketConditionsRiskMember"
      id="x_003fa906-73db-49d7-b3df-0bf615125b32">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CURRENT MARKET CONDITIONS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Current market conditions risk is the risk that a particular investment, or shares of &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;the Fund in general, may fall in value due to current market conditions. As a means to fight inflation, the Federal Reserve and certain foreign central banks have raised interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund&#x2019;s ability to achieve its investment strategies or make certain investments. Potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including high interest rates, declining valuations and elevated vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund&#x2019;s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among the United States, Israel, Iran, Hamas, Hezbollah and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East, the United States, and other nations. Such events may also disrupt global trade and supply chains, increase sanctions and other governmental actions, and contribute to volatility in oil and natural gas markets. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund&#x2019;s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;affect the prices and liquidity of the Fund&#x2019;s portfolio investments and could result in disruptions in the trading markets.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CustodialReceiptsTrustRiskMember"
      id="x_1275ad56-e8bc-4f84-81a9-ebd28045130a">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CUSTODIAL RECEIPTS TRUST RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Custodial receipts are financial instruments sold through private placements that &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;represent the right to receive future principal and interest payments on underlying municipal obligations. Custodial receipt trusts may also issue inverse floater securities. If the Fund was to hold inverse floaters issued by custodial receipt trusts, the Fund would be subject to the risks of inverse floaters described herein. In particular, because the instruments may be leveraged, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;their market values may be more volatile than other types of debt securities.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_CyberSecurityRiskMember"
      id="b5b6f133-b0a5-49f1-9bf5-b0111ddcb8bd">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;CYBER SECURITY RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund is susceptible to operational, information security and related risks through breaches in &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;cyber security. A breach in cyber security refers to both intentional and unintentional events that may cause the Fund to lose proprietary information, suffer data corruption or lose operational capacity, any of which could result in a material adverse effect on the Fund or its shareholders. Such events could cause the Fund to incur regulatory penalties, reputational damage, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;additional compliance costs associated with corrective measures and/or financial loss. Cyber security breaches may involve unauthorized access to the Fund&#x2019;s digital information systems through &#x201c;hacking&#x201d; or malicious software coding but may also result from outside attacks such as denial-of-service attacks through efforts to make network services unavailable to intended users. Emerging threats like ransomware or zero-day exploits could also cause disruptions to Fund operations. In addition, cyber security breaches of the issuers of securities in which the Fund invests or the Fund&#x2019;s third-party service providers, such as its administrator, transfer agent, custodian, or sub-advisor, as applicable, among many other third-party service providers, can also subject the Fund to many of the same risks associated with direct cyber security breaches. Further, errors, misconduct, or compromise of accounts of employees of the Fund or its third-party service providers can also create material cybersecurity risks. Although the Fund has established risk management systems designed to reduce the risks associated with cyber security, there is no guarantee that such efforts will succeed, especially because the Fund does not directly control the cyber security systems of issuers or third-party service providers. Cyber security incidents may also trigger Fund obligations under data privacy laws, potentially increasing notification and compliance burdens. Cyber security incidents affecting issuers in whose securities the Fund invests may also have a negative impact on the value of the securities of such issuers, and in turn, the value of the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_DebtSecuritiesRiskMember"
      id="fb7806be-8b9f-45c3-b356-ed646d57c890">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;DEBT SECURITIES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Investments in debt securities subject the holder to the credit risk of the issuer. Credit risk refers to &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;the possibility that the issuer or other obligor of a security will not be able or willing to make payments of interest and principal when due. Generally, the value of debt securities will change inversely with changes in interest rates. To the extent that interest rates rise, certain underlying obligations may be paid off substantially slower than originally anticipated and the value of those securities may fall sharply. During periods of falling interest rates, the income received by the Fund may decline. If the principal on a debt security is prepaid before expected, the prepayments of principal may have to be reinvested in obligations paying interest at lower rates. Debt securities generally do not trade on a securities exchange making them generally less liquid and &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;more difficult to value than common stock.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_DerivativesRiskMember"
      id="x_9643e6f5-7b25-47ad-9de1-eeaee9015c85">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;DERIVATIVES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The use of derivative instruments involves risks different from, or possibly greater than, the risks associated &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;with investing directly in securities and other traditional investments. These risks include or may include: (i) the risk that the value of the underlying assets may go up or down; (ii) the risk that the counterparty to a derivative transaction may not fulfill its contractual obligations; (iii) the risk of mispricing or improper valuation of a derivative; (iv) the risk that changes in the value of the derivative may not correlate perfectly with the underlying asset; (v) the risk that a derivative instrument cannot be sold, closed out or replaced quickly at or very close to its fundamental value; (vi) the risk of loss caused by the unenforceability of a party&#x2019;s obligations under the derivative; and (vii) the risk that a disruption in the financial markets will cause difficulties for all market participants. Derivative prices are highly volatile and may fluctuate substantially during a short period of time. Such prices are influenced by numerous factors that affect the markets, including, but not limited to: changing supply and demand relationships; government programs and policies; national and international political and economic events, changes in interest rates, inflation and deflation and changes in supply and demand relationships. Trading derivative instruments involves risks different from, or possibly greater than, the risks associated with investing directly in securities. Derivative contracts ordinarily have leverage inherent in their terms. The low margin deposits normally required in trading derivatives, including futures contracts, permit a high degree of leverage. Accordingly, a relatively small price movement may result in an immediate and substantial loss. The use of leverage may also cause the Fund to liquidate portfolio positions when it would not be advantageous to do so. The use of leveraged derivatives can magnify potential for gain or loss and, therefore, amplify the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;effects of market volatility on share price.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_DistressedSecuritiesRiskMember"
      id="x_0b967e53-3cc5-421b-adf7-8cf258b8d9db">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;DISTRESSED SECURITIES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Distressed debt securities are speculative and involve substantial risks in addition to the risks &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;of investing in high-yield securities that are not in default. In some instances, the Fund will not receive interest payments from the distressed securities it holds, and there is a substantial risk that the principal will not be repaid. In any reorganization or &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;liquidation proceeding related to a distressed debt security, the Fund may lose its entire investment in the security.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_ExtensionRiskMember"
      id="da4cbb70-e1fc-4262-aca9-9fbdb95a0931">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;EXTENSION RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Extension risk is the risk that, when interest rates rise, certain obligations will be paid off by the issuer (or &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;other obligated party) more slowly than anticipated, causing the value of these debt securities to fall. Rising interest rates tend to extend the duration of debt securities, making their market value more sensitive to changes in interest rates. The value of longer-term debt securities generally changes more in response to changes in interest rates than shorter-term debt &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;securities. As a result, in a period of rising interest rates, securities may exhibit additional volatility and may lose value.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_FuturesContractsRiskMember"
      id="x_130adb3e-6d5c-4955-a969-de98fddd8bcd">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;FUTURES CONTRACTS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Futures contracts are typically exchange-traded contracts that call for the future delivery of &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;an asset by one party to another at a certain price and date, or cash settlement of the terms of the contract. The risk of a position in a futures contract may be very large compared to the relatively low level of margin the Fund is required to deposit. In many cases, a relatively small price movement in a futures contract may result in immediate and substantial loss or gain to &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;the investor relative to the size of a required margin deposit. In the event no secondary market exists for a particular contract, it might not be possible to effect closing transactions, and the Fund will be unable to terminate the derivative. If the Fund uses futures contracts for hedging purposes, there is a risk of imperfect correlation between movements in the prices of the derivatives and movements in the securities or index underlying the derivatives or movements in the prices of the Fund's investments that are the subject of such hedge. The prices of futures contracts may not correlate perfectly with movements &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;in the securities or index underlying them.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_HighYieldSecuritiesRiskMember"
      id="a266b436-75d1-452d-b9ca-358283d24185">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;HIGH YIELD SECURITIES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; High yield securities, or &#x201c;junk&#x201d; bonds, are subject to greater market fluctuations, are less liquid &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and provide a greater risk of loss than investment grade securities, and therefore, are considered to be highly speculative. In general, high yield securities may have a greater risk of default than other types of securities and could cause income and &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;principal losses for the Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_IncomeRiskMember"
      id="x_45103b09-bfa2-4630-8dfe-cc694725c9b3">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;INCOME RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund&#x2019;s income may decline when interest rates fall or if there are defaults in its portfolio. This decline can &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;occur because the Fund may subsequently invest in lower-yielding securities as debt securities in its portfolio mature, are &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;near maturity or are called, or the Fund otherwise needs to purchase additional debt securities.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_IndustrialDevelopmentBondRiskMember"
      id="x_75df49f6-70ca-4aef-a782-17e5c61e5a41">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;INDUSTRIAL DEVELOPMENT BOND RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; To the extent that investments in the industrial development sector represent a &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;significant portion of the Fund&#x2019;s portfolio, the Fund will be sensitive to changes in, and its performance may depend to a greater extent on, the overall condition of the industrial development sector. These bonds are normally secured only by the revenues from the project and are not general obligations of the issuer or otherwise secured by state or local government tax receipts. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;Generally, the value and credit quality of these bonds are sensitive to the risks related to an economic slowdown.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_InflationRiskMember"
      id="x_1e4b47d9-54a1-40f1-9216-d1573bfba106">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;INFLATION RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Inflation risk is the risk that the value of assets or income from investments will be less in the future as &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;inflation decreases the value of money. As inflation increases, the present value of the Fund&#x2019;s assets and distributions may &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;decline.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_InterestRateRiskMember"
      id="d40565be-9765-4d4a-afeb-403f71d289cb">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;INTEREST RATE RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Interest rate risk is the risk that the value of the debt securities in the Fund&#x2019;s portfolio will decline &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;because of rising market interest rates. Interest rate risk is generally lower for shorter term debt securities and higher for longer-term debt securities. The Fund may be subject to a greater risk of rising interest rates than would normally be the case during periods of low interest rates. Duration is a reasonably accurate measure of a debt security&#x2019;s price sensitivity to changes in interest rates and a common measure of interest rate risk. Duration measures a debt security&#x2019;s expected life on a present value basis, taking into account the debt security&#x2019;s yield, interest payments and final maturity. In general, duration represents the expected percentage change in the value of a security for an immediate 1% change in interest rates. For example, the price of a debt security with a three-year duration would be expected to drop by approximately 3% in response to a 1% increase in interest rates. Therefore, prices of debt securities with shorter durations tend to be less sensitive to interest rate changes than debt securities with longer durations. Higher sensitivity to interest rates is generally correlated with higher levels of &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;volatility and, therefore, greater risk. As the value of a debt security changes over time, so will its duration.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_InverseFloatersRiskMember"
      id="x_2a408eff-d1bb-44b0-97c4-1d1c3638d5e5">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;INVERSE FLOATERS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund may invest in inverse floaters, which are debt instruments that pay interest at a rate &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;that moves inversely to a designated reference rate (typically an interest rate benchmark). Inverse floaters may be structured from municipal bonds, mortgage-backed securities or other types of fixed income securities. Distributions paid to the Fund on its inverse floaters will decrease (or possibly be eliminated) as interest rates rise and will increase when interest rates fall. Accordingly, inverse floaters will generally underperform the market for fixed- and floating-rate debt securities in a rising interest rate environment. The inverse payout structure of such instruments is created through structural leverage, which can cause the market value of inverse floaters to be more sensitive to changes in interest rates than more traditional fixed- or floating-rate debt securities. As a result, small movements in interest rates can produce disproportionate changes in the value of such holdings. Inverse floaters may also be subject to liquidity risk and structural complexity, which can make them more difficult to value or sell. The transactions that give rise to the creation of an inverse floater may be terminated without the Fund&#x2019;s consent upon the occurrence of certain events, such as the bankruptcy or other default by the issuer. Such an event could &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;result in a loss of principal for the Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_ManagementRiskMember"
      id="x_6ff38755-cca5-4d9b-8ba3-63ab6b740c55">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MANAGEMENT RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund is subject to management risk because it is an actively managed portfolio. In managing the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Fund&#x2019;s investment portfolio, the portfolio managers will apply investment techniques and risk analyses that may not produce &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;the desired result. There can be no guarantee that the Fund will meet its investment objective.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_MarketMakerRiskMember"
      id="x_88498b06-69b0-40ce-812c-8925f632ea64">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MARKET MAKER RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund faces numerous market trading risks, including the potential lack of an active market for &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Fund shares due to a limited number of market makers. Decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;maintaining the relationship between the underlying values of the Fund&#x2019;s portfolio securities and the Fund&#x2019;s market price. The Fund may rely on a small number of third-party market makers to provide a market for the purchase and sale of shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund&#x2019;s net asset value and the price at which the Fund&#x2019;s shares are trading on the Exchange, which could result in a decrease in value of the Fund&#x2019;s shares. This reduced effectiveness could result in Fund shares trading at a &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;discount to net asset value and also in greater than normal intraday bid-ask spreads for Fund shares.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_MarketRiskMember"
      id="x_0c92e66e-e1ab-45d4-aadd-ac226e9846b7">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MARKET RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Market risk is the risk that a particular investment, or shares of the Fund in general, may fall in value. Securities &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates and perceived trends in securities prices. Shares of the Fund could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of the Fund&#x2019;s shares, the liquidity of an investment, and may result in increased market volatility. During any such events, the Fund&#x2019;s shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on the Fund&#x2019;s shares may widen and the returns on investment may &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;fluctuate.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_MunicipalLeaseParticipationsRiskMember"
      id="f2ab541d-4cd2-4809-9055-d69456b04ba8">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MUNICIPAL LEASE PARTICIPATIONS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Participation interests in municipal leases pose special risks because many leases &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and contracts contain &#x201c;non-appropriation&#x201d; clauses that provide that the governmental issuer has no obligation to make future &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;payments under the lease or contract unless money is appropriated for this purpose by the appropriate legislative body.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_MunicipalSecuritiesMarketLiquidityRiskMember"
      id="x_0b6778d6-ef63-408a-ab09-2ac0d6cc83ff">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MUNICIPAL SECURITIES MARKET LIQUIDITY RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; From time to time, inventories of municipal securities held by brokers &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and dealers may decrease, lessening their ability to make a market in these securities. Any reduction in market making capacity has the potential to decrease the Fund&#x2019;s ability to buy or sell municipal securities, and increase price volatility and trading costs, particularly during periods of economic or market stress. As a result, the Fund may be forced to accept a lower price to sell a municipal security, to sell other securities to raise cash, or to give up an investment opportunity, any of which could &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;have a negative effect on performance.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_MunicipalSecuritiesRiskMember"
      id="e002635e-31dc-4184-92da-e2bc8c065e34">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;MUNICIPAL SECURITIES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Issuers, including governmental issuers, may be unable to pay their obligations as they come &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;due. The values of municipal securities that depend on a specific revenue source to fund their payment obligations may fluctuate as a result of actual or anticipated changes in the cash flows generated by the revenue source or changes in the priority of the municipal obligation to receive the cash flows generated by the revenue source. The values of municipal securities held by the Fund may be adversely affected by local political and economic conditions and developments. Adverse conditions in an industry significant to a local economy could have a correspondingly adverse effect on the financial condition of local issuers. In addition, income from municipal securities held by the Fund could be declared taxable because of, among other things, unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state tax authorities, or noncompliant conduct of an issuer or other obligated party. Loss of tax-exempt status may cause interest received and distributed to shareholders by the Fund to be taxable and may result in a significant decline in the values of such municipal securities. Due to the COVID-19 pandemic, the risks of the municipal securities market have been magnified. The costs associated with combating the pandemic and the negative impact on tax revenues has adversely affected the financial condition of many states and political subdivisions. These risks may also adversely affect several sectors of the municipal bond market, such as airports, toll roads, hospitals and colleges, among many others. The full impact of the COVID-19 pandemic on state and political subdivisions&#x2019; ability to make payments on debt obligations is impossible to predict, but could negatively impact the value of bonds, the ability of state and political subdivisions to make payments when due and the performance of the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;Fund.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_OperationalRiskMember"
      id="x_05cfe883-e498-463b-8213-ef10aa6a05c3">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;OPERATIONAL RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The Fund is subject to risks arising from various operational factors, including, but not limited to, human &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;error, processing and communication errors, errors of the Fund&#x2019;s service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. These errors or failures may adversely affect the Fund&#x2019;s operations, including its ability to execute its investment process, calculate or disseminate its NAV or intraday indicative optimized portfolio value in a timely manner, and process creations or redemptions. The Fund relies on third-parties for a range of services, including custody, valuation, administration, transfer services, securities lending and accounting, among many others. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund&#x2019;s ability to meet its investment objective. Although the Fund and the Fund's investment advisor seek to reduce these operational risks through controls and procedures, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;there is no way to completely protect against such risks.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_PremiumDiscountRiskMember"
      id="a3803293-01b9-42c2-bf33-cd3b3c15f5c8">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;PREMIUM/DISCOUNT RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The market price of the Fund&#x2019;s shares will generally fluctuate in accordance with changes in the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Fund&#x2019;s net asset value as well as the relative supply of and demand for shares on the Exchange. The Fund&#x2019;s investment advisor cannot predict whether shares will trade below, at or above their net asset value because the shares trade on the Exchange at market prices and not at net asset value. 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 net asset value), the Fund&#x2019;s investment advisor believes that large discounts or premiums to the net asset value of shares should not be sustained. During stressed market conditions, the market for the Fund&#x2019;s shares may become less liquid in response to deteriorating liquidity in the market for the Fund&#x2019;s underlying portfolio holdings, which could in turn lead to differences between the market price of the Fund&#x2019;s shares and their net asset &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;value and the bid/ask spread on the Fund&#x2019;s shares may widen.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_PrepaymentRiskMember"
      id="dfb028c8-04d9-4a1a-9523-4a915662b198">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;PREPAYMENT RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Prepayment risk is the risk that the issuer of a debt security will repay principal prior to the scheduled &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;maturity date. Debt securities allowing prepayment may offer less potential for gains during a period of declining interest rates, as an underlying fund may be required to reinvest the proceeds of any prepayment at lower interest rates. These factors &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;may cause the value of an investment in an underlying fund to change.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_PreRefundedBondsRiskMember"
      id="x_28235f37-e3af-4281-89ca-9d347a7948a9">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;PRE-REFUNDED BONDS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Pre-refunded bonds are bonds that have been refunded to a call date prior to the final maturity &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;of principal, or, in the case of pre-refunded bonds commonly referred to as &#x201c;escrowed-to-maturity bonds,&#x201d; to the final maturity of principal, and remain outstanding in the municipal market. The payment of principal and interest of the pre-refunded bonds held by the Fund is funded from securities held in a designated escrow account where such securities are obligations of and carry the full faith and credit of the U.S. Department of the Treasury. The securities held in the escrow fund pledged to pay the principal and interest of the pre-refunded bond do not guarantee the price of the bond. Investment in pre-refunded &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;municipal bonds held by the Fund may subject the Fund to interest rate risk, market risk and credit risk.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_PrivateActivityBondsRiskMember"
      id="e4578151-1901-4478-9d05-c0bc8069b36f">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;PRIVATE ACTIVITY BONDS RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Municipalities and other public authorities issue private activity bonds to finance &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;development of industrial facilities for use by a private enterprise. The private enterprise is responsible for the payment of principal and interest on the bond and the issuer ordinarily does not pledge its full faith, credit and taxing power for repayment. The private enterprise can have a substantially different credit profile than the issuer. The private activity bonds in which the Fund may invest may be negatively impacted by conditions affecting either the general credit of the private enterprise or the project itself. The Fund's or an underlying fund&#x2019;s private activity bond holdings may also pay interest subject to the alternative minimum tax on individuals. For tax years beginning after December 31, 2022, interest on the bonds may affect the corporate &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;alternative minimum tax for certain corporations.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_SignificantExposureRiskMember"
      id="x_3e618ae7-e931-4e39-af41-78a9a04659f5">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;SIGNIFICANT EXPOSURE RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; To the extent that the Fund invests a significant percentage of its assets in a single asset class &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;or the securities of issuers within the same country, state, region, industry or sector, an adverse economic, business or political development may affect the value of the Fund&#x2019;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 &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;fund that is more broadly diversified.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_TenderOptionBondRiskMember"
      id="e3ba1ae2-5a7f-4404-980a-737074ad54fa">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;TENDER OPTION BOND RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Tender option bond investments involve leverage and credit risk, and generally involve greater &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;risk than investments in fixed rate municipal bonds, including the risk of loss of principal. Tender option bond investments may also subject the Fund to the risks of inverse floaters described herein. In particular, because the instruments may be &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;leveraged, their market values may be more volatile than other types of debt securities.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_TradingIssuesRiskMember"
      id="a34b45fb-a6b4-4491-bbc2-6ecd705526e9">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;TRADING ISSUES RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; Trading in Fund shares on the Exchange may be halted due to market conditions or for reasons that, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange&#x2019;s &#x201c;circuit breaker&#x201d; rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund&#x2019;s assets are &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="S000053970_ValuationRiskMember"
      id="bd7c1675-81db-4893-9f1a-b938e19ec17b">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;margin-left:0%;"&gt;VALUATION RISK.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt; The sale price the Fund could receive for a security may differ from the Fund&#x2019;s valuation of the security, &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;particularly for securities that trade in low volume or volatile markets or that are valued using a fair value methodology. Unlike publicly traded securities that trade on national securities exchanges, there is no central place or exchange for trading most debt securities. Debt securities generally trade on an &#x201c;over-the-counter&#x201d; market. Due to the lack of centralized information &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and trading, and variations in lot sizes of certain debt securities, the valuation of debt securities may carry more uncertainty and risk than that of publicly traded securities. Debt securities are commonly valued by third-party pricing services that utilize a range of market-based inputs and assumptions, including readily available market quotations obtained from broker-dealers making markets in such securities, cash flows and transactions for comparable instruments. However, because the available information is less reliable and more subjective, elements of judgment may play a greater role in valuation of debt securities than for other types of securities. Different pricing services may incorporate different assumptions and inputs into their valuation methodologies, potentially resulting in different values for the same securities. As a result, if the Advisor were to change its valuation policies, or if the Fund were to change pricing services, or if a pricing service were to change its valuation methodology, there could be a material impact, either positive or negative, on the Fund&#x2019;s net asset value. Additionally, pricing services generally price debt securities assuming orderly transactions of an institutional &#x201c;round lot&#x201d; size, but some trades may occur in smaller, &#x201c;odd lot&#x201d; sizes, often at lower prices than institutional round lot trades. There is no assurance that the Fund will be able to sell a portfolio security at the price established by the pricing service, which could result in a loss to the Fund. In addition, the value of the debt securities in the Fund's portfolio may change on days or during time periods when shareholders will not be able to purchase or sell the Fund's shares. Authorized Participants who purchase or redeem Fund shares on days when the Fund is holding fair-valued securities may receive fewer or more shares, or lower or higher redemption proceeds, than they would have received had the Fund not fair-valued securities or used a different valuation methodology. Net asset &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;value calculation may also be impacted by operational risks arising from factors such as failures in systems and technology.&lt;/span&gt;</oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="S000053970"
      id="b40a54fe-8c9d-452f-8843-bd6cbac2465a">&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;Annual Total Return&lt;/span&gt;</oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="S000053970"
      id="x_234c57a1-40bc-4632-80cb-1d9826219604">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;The bar chart and table below illustrate the annual calendar year returns of the Fund based on net asset value as well as the average annual Fund returns. The bar chart and table provide an indication of the risks of investing in the Fund by showing changes in the Fund&#x2019;s performance from year-to-year and by showing how the Fund&#x2019;s average annual total returns based on net asset value compared to those of a market index, a blended benchmark, and a broad based securities market index. &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;The Fund&#x2019;s performance information is accessible on the Fund&#x2019;s website at &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;http://www.ftportfolios.com&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;.&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;On April 14, 2022, the Fund&#x2019;s investment strategy changed. Prior to April 14, 2022, the Fund sought to achieve its investment objective of providing current income through investments in closed-end funds and ETFs that held municipal debt securities. Following April 14, 2022, the Fund seeks to achieve this investment objective primarily through direct investments in municipal debt securities. Therefore, the Fund&#x2019;s performance and historical returns shown below are not necessarily indicative of the &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;performance that the Fund would have generated based upon its current strategy.&lt;/span&gt;</oef:PerformanceNarrativeTextBlock>
    <oef:PerformanceInformationIllustratesVariabilityOfReturns
      contextRef="S000053970"
      id="x_8f85aea2-d9dc-4f55-bbd4-740891f1fb43">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;The bar chart and table below illustrate the annual calendar year returns of the Fund based on net asset value as well as the average annual Fund returns. The bar chart and table provide an indication of the risks of investing in the Fund by showing changes in the Fund&#x2019;s performance from year-to-year and by showing how the Fund&#x2019;s average annual total returns based on net asset value compared to those of a market index, a blended benchmark, and a broad based securities market index. &lt;/span&gt;</oef:PerformanceInformationIllustratesVariabilityOfReturns>
    <oef:PerformanceAvailabilityWebSiteAddress
      contextRef="S000053970"
      id="x_6c0eadd2-2ee9-4653-90b1-767f2d16ab26">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;http://www.ftportfolios.com&lt;/span&gt;</oef:PerformanceAvailabilityWebSiteAddress>
    <oef:BarChartHeading
      contextRef="S000053970"
      id="e6d61f5e-750f-4ffe-af24-2b1792041e94">&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;First Trust Flexible Municipal High Income ETF&lt;/span&gt;
&lt;br/&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;Calendar Year Total Returns as of 12/31 &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:7pt;font-weight:bold;position:relative;top:-3.25pt;"&gt;(1)&lt;/span&gt;</oef:BarChartHeading>
    <oef:BarChartFootnotesTextBlock
      contextRef="S000053970"
      id="c2f55352-9e96-467e-8fae-647ec23dd2ff">&lt;span style="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;"&gt;(1)&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;"&gt;The Fund's calendar year-to-date total return based on net asset value for the period 12/31/24 to 09/30/25 was 1.87%.&lt;/span&gt;</oef:BarChartFootnotesTextBlock>
    <oef:BarChartClosingTextBlock
      contextRef="S000053970"
      id="x_75d5e37f-d426-4154-a250-4ba738067e9c">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;During the periods shown in the chart above:&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;"&gt;Return&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;"&gt;Period Ended&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Best Quarter&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;7.94%&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;December 31, 2023&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Worst Quarter&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;-13.43%&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;March 31, 2022&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Year-to-Date&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;1.87%&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;September 30, 2025&lt;/span&gt;</oef:BarChartClosingTextBlock>
    <oef:HighestQuarterlyReturnLabel
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      id="ab9e46af-bf23-4fcd-99eb-fcf5f9bc81b6">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Best Quarter&lt;/span&gt;</oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="S000053970_C000169822"
      decimals="4"
      id="x_9921e396-4d0f-4272-b21d-75a966a72eb9"
      unitRef="pure">0.0794</oef:BarChartHighestQuarterlyReturn>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="S000053970_C000169822"
      id="ade68027-808c-4e1d-b2a9-5a33bad53c33">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:LowestQuarterlyReturnLabel
      contextRef="S000053970_C000169822"
      id="x_1033c0af-902f-47ef-ae0e-fe742a3b1bf5">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Worst Quarter&lt;/span&gt;</oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturn
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      id="x_686dfd6b-dc20-48d7-87c0-ab8b5e5d3d6e"
      unitRef="pure">-0.1343</oef:BarChartLowestQuarterlyReturn>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="S000053970_C000169822"
      id="x_38d53ee4-8b20-4511-9ff8-b55a8dc26b91">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:YearToDateReturnLabel
      contextRef="S000053970_C000169822"
      id="a2de08b1-e0b6-4b0f-92ac-6a3f2b52cb0c">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;"&gt;Year-to-Date&lt;/span&gt;</oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturn
      contextRef="S000053970_C000169822"
      decimals="4"
      id="adbe4a70-111f-4f38-970c-0fd092aeb556"
      unitRef="pure">0.0187</oef:BarChartYearToDateReturn>
    <oef:BarChartYearToDateReturnDate
      contextRef="S000053970_C000169822"
      id="x_5251f637-c32d-4353-8e10-4f0b2d560a0f">2025-09-30</oef:BarChartYearToDateReturnDate>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="S000053970"
      id="x_4429a376-646b-4c22-bacc-606419475ecd">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;The Fund&#x2019;s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.&lt;/span&gt;</oef:PerformancePastDoesNotIndicateFuture>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="S000053970"
      id="deec129f-0424-4764-9fa1-af6401c87b36">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state or local tax.&lt;/span&gt;</oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="S000053970"
      id="x_92759d50-0fd1-4452-aeca-2d24a36cf160">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;Returns after taxes on distributions reflect the taxed return on the payment of dividends &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;and capital gains. Returns after taxes on distributions and sale of shares assume you sold your shares at period end, and, therefore, are also adjusted for any capital gains or losses incurred. Returns for an index do not include expenses, which are &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;deducted from Fund returns, or taxes.&lt;/span&gt;</oef:PerformanceTableExplanationAfterTaxHigher>
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      contextRef="S000053970"
      id="x_251340b7-aa4c-4969-82a0-03ba6b21fc1d">&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;"&gt;Your own actual after-tax returns will depend on your specific tax situation and may differ from what is shown here. After-tax returns are not relevant to investors who hold Fund shares in tax-deferred accounts such as individual retirement accounts &lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;(&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;"&gt;IRAs&lt;/span&gt;&lt;span style="color:#000000;font-family:Arial;font-size:9.00pt;"&gt;) or employee-sponsored retirement plans.&lt;/span&gt;</oef:PerformanceTableNotRelevantToTaxDeferred>
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      id="a29bf135-5ff4-42bd-abcb-ff09d3f0df6d">&lt;span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;"&gt;Average Annual Total Returns for the Periods Ended December 31, 2024&lt;/span&gt;</oef:PerformanceTableHeading>
    <oef:AvgAnnlRtrPct
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      decimals="4"
      id="x_55e29fc7-d004-43fa-84a5-436300e5d889"
      unitRef="pure">0.0465</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_01Jan2020_31Dec2024"
      decimals="4"
      id="x_37653766-bfd9-4d14-8a34-e5a95c7c5b81"
      unitRef="pure">0.0106</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000169822_27Sep2016_31Dec2024"
      decimals="4"
      id="d1d5065a-22df-4cc2-8c22-7156ad0a2313"
      unitRef="pure">0.0173</oef:AvgAnnlRtrPct>
    <oef:PerfInceptionDate
      contextRef="C000169822"
      id="x_16f88034-2be5-413b-bf39-5fd968ab14c4">2016-09-27</oef:PerfInceptionDate>
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      contextRef="C000169822_AfterTaxesOnDistributionsMember_01Jan2024_31Dec2024"
      decimals="4"
      id="x_3691ac52-1a1c-4281-9030-89ba86184a49"
      unitRef="pure">0.0465</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_AfterTaxesOnDistributionsMember_01Jan2020_31Dec2024"
      decimals="4"
      id="x_06977edf-346c-44e0-9002-a50be9c8b486"
      unitRef="pure">0.0106</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_AfterTaxesOnDistributionsMember_27Sep2016_31Dec2024"
      decimals="4"
      id="x_9337dcd3-03e2-481f-9d2b-ccb1d491b027"
      unitRef="pure">0.0172</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_AfterTaxesOnDistributionsAndSalesMember_01Jan2024_31Dec2024"
      decimals="4"
      id="e45890e2-cf42-467c-89a6-ee90a81c379f"
      unitRef="pure">0.0434</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_AfterTaxesOnDistributionsAndSalesMember_01Jan2020_31Dec2024"
      decimals="4"
      id="x_241199e3-958c-4d78-953b-bd908e21b56b"
      unitRef="pure">0.0167</oef:AvgAnnlRtrPct>
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      contextRef="C000169822_AfterTaxesOnDistributionsAndSalesMember_27Sep2016_31Dec2024"
      decimals="4"
      id="x_17c4f204-fa42-44f7-b2d2-68f5de261af3"
      unitRef="pure">0.0214</oef:AvgAnnlRtrPct>
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      contextRef="_BloombergMunicipalLongBond22PlusIndexMember_01Jan2024_31Dec2024"
      decimals="4"
      id="x_8a080b42-6d7e-4b47-9598-f630c49ac3a3"
      unitRef="pure">0.0140</oef:AvgAnnlRtrPct>
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      contextRef="_BloombergMunicipalLongBond22PlusIndexMember_01Jan2020_31Dec2024"
      decimals="4"
      id="d70d517b-5911-4552-abe9-6637fd7eb97f"
      unitRef="pure">0.0052</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="_BloombergMunicipalLongBond22PlusIndexMember_27Sep2016_31Dec2024"
      decimals="4"
      id="b9ba56d1-9614-473b-8249-dd7031d0531e"
      unitRef="pure">0.0186</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="_MFLXBlendedBenchmarkMember_01Jan2024_31Dec2024"
      decimals="4"
      id="a34fdd15-48ca-47e7-a376-33fcdcfe4388"
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      id="x_409efdce-d890-4fef-b958-4b9d96683c98">&lt;span style="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;"&gt;The Blended Benchmark returns are a 50/50 split between the Bloomberg Municipal High Yield Bond Index and the Bloomberg Municipal Bond Index.&lt;/span&gt;</oef:PerformanceAdditionalMarketIndex>
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