N-2
N-2 - USD ($) $ / shares in Units, $ in Thousands | 12 Months Ended | |||||
Mar. 31, 2024 | Mar. 31, 2023 | Mar. 31, 2022 | Mar. 31, 2021 | Mar. 31, 2020 | ||
Cover [Abstract] | ||||||
Entity Central Index Key | 0001258943 | |||||
Amendment Flag | false | |||||
Document Type | N-CSR/A | |||||
Entity Registrant Name | Pioneer Municipal High Income Advantage Fund, Inc. | |||||
Financial Highlights [Abstract] | ||||||
Senior Securities [Table Text Block] | Year Year Year Year Year Per Share Operating Performance Net asset value, beginning of period $ $ $ $ $ Increase (decrease) from investment operations:(a) Net investment income (loss)(b) $ $ $ $ $ Net realized and unrealized gain (loss) on investments (0.23) (1.28) (1.38) 0.42 0.06 Net increase (decrease) from investment operations $ $ $ $ $ Distributions to stockholders: Net investment income and previously undistributed net investment income $ $ $ $ $ Tax return of capital — (0.07) — — — Total distributions $ $ $ $ $ Net increase (decrease) in net asset value $ $ $ $ $ Net asset value, end of period $ $ $ $ $ Market value end of period $ $ $ $ $ Total return at net asset value(c) 2.49%(d) (7.42)% (7.54)% 8.60% 5.12% Total return at market value(c) 3.59% (11.26)% (13.03)% 22.05% (1.30)% Ratios to average net assets of stockholders: Total expenses plus interest expense(e)(f) 4.76% 3.40% 1.86% 1.82% 2.61% Net investment income 4.32% 4.29% 4.02% 4.33% 4.14% Portfolio turnover rate 16% 63% 11% 12% 11% Net assets of common stockholders, end of period (in thousands) $220,077 $224,545 $257,047 $290,614 $281,372 Preferred shares outstanding (in thousands)(g)(h)(i)(j) $50,000 $140,000 $180,000 $180,000 $160,000 Asset coverage per preferred share, end of period $540,154 $260,389 $242,804 $261,452 $276,030 Average market value per preferred share(k) $100,000 $100,000 $100,000 $100,000 $100,000 Liquidation value, including interest expense payable, per preferred share $100,000 $100,000 $100,000 $100,000 $100,172 * The amount of distributions made to shareowners during the period was in excess of the net investment income earned by the Fund during the period. The Fund has accumulated undistributed net investment income which is part of the Fund’s NAV. A portion of this accumulated net investment income was distributed to shareowners during the period. A decrease in distributions may have a negative effect on the market value of the Fund’s shares. (a) The per common share data presented above is based upon the average common shares outstanding for the periods presented. (b) Beginning March 31, 2020, distribution payments to preferred shareowners are included as a component of net investment income. The accompanying notes are an integral part of these financial statements. Table of Contents (c) Total investment return is calculated assuming a purchase of common shares at the current net asset value or market value on the first day and a sale at the current net asset value or market value on the last day of the periods reported. Dividends and distributions, if any, are assumed for purposes of this calculation to be reinvested at prices obtained under the Fund’s dividend reinvestment plan. Total investment return does not reflect brokerage commissions. Past performance is not a guarantee of future results. (d) For the year ended March 31, 2024, the Fund’s total return includes a reimbursement by the Adviser (see Notes to the Financial Statements-Note 1B). The impact on total return was less than 0.005%. (e) Includes interest expense of 3.47%, 2.09%, 0.56%, 0.64% and 1.50%, respectively. (f) Prior to March 31, 2020, the expense ratios do not reflect the effect of distribution payments to preferred shareowners. (g) The Fund redeemed 900 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on February 29, 2024. (h) The Fund redeemed 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on November 14, 2022. (i) The Fund redeemed 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on September 29, 2022. (j) The Fund issued 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on February 16, 2021. (k) Market value is redemption value without an active market. | |||||
Senior Securities Amount | [1],[2],[3],[4] | $ 50,000 | $ 140,000 | $ 180,000 | $ 180,000 | $ 160,000 |
Senior Securities Coverage per Unit | $ 540,154 | $ 260,389 | $ 242,804 | $ 261,452 | $ 276,030 | |
Preferred Stock Liquidating Preference | 100,000 | 100,000 | 100,000 | 100,000 | 100,172 | |
Senior Securities Average Market Value per Unit | [5] | $ 100,000 | 100,000 | $ 100,000 | $ 100,000 | $ 100,000 |
General Description of Registrant [Abstract] | ||||||
Investment Objectives and Practices [Text Block] | INVESTMENT OBJECTIVES The Fund’s primary investment objective is to provide its common stockholders with a high level of current income exempt from regular federal income tax. Distributions of interest income from the Fund’s portfolio of municipal securities generally will be exempt from regular federal income tax. As a secondary investment objective, the Fund also may seek capital appreciation to the extent consistent with its primary objective. Distributions from sources other than interest income from the Fund’s portfolio of municipal securities, including capital gain distributions, are not exempt from regular federal income tax. The Fund’s investment objectives and its policy with respect to investment in municipal securities are fundamental policies and may not be changed without the approval of a majority of the outstanding voting securities (as defined in the 1940 Act) of the Fund. There can be no assurance that the Fund will achieve its investment objectives. PRINCIPAL INVESTMENT STRATEGIES Under normal market conditions, the Fund will invest substantially all (at least 80%) of its assets (net assets plus borrowings for investment purposes) in debt securities and other obligations issued by or on behalf of states, territories and possessions of the United States and the District of Columbia and their political subdivisions, agencies and instrumentalities, the interest on which is exempt from regular federal income tax (“municipal securities”). Municipal securities are often issued to obtain funds for various public purposes, including the construction of a wide range of public facilities such as bridges, highways, housing, hospitals, mass transportation, schools, streets and water and sewer works. Municipal securities include private activity bonds, pre-refunded municipal securities and auction rate securities. The municipal securities in which the Fund invests may have fixed or variable principal payments and all types of interest rate payments and reset terms, including fixed rate, adjustable rate, zero coupon, contingent, deferred, payment in kind and auction rate features. Table of Contents Although distributions of interest income from the Fund’s municipal securities generally are exempt from regular federal income tax, distributions from other sources, including capital gain distributions, are not. The Fund is not limited in the portion of its assets that may be invested in municipal securities the interest income on which is a preference item for purposes of the alternative minimum tax for individuals or entities that are subject to such tax. All interest on municipal securities may result in or increase a corporate stockholder’s liability for federal alternative minimum tax. stockholders should consult a tax adviser about whether an alternative minimum tax applies to them and about state and local taxes on their distributions from the Fund. The Fund may invest in municipal securities with a broad range of maturities and credit ratings, including both investment grade and below investment grade municipal securities. In managing the Fund’s portfolio, the Adviser adjusts the portfolio’s duration and overall credit quality in light of changing market and economic conditions. In making decisions with respect to specific municipal securities for the Fund’s portfolio, the Adviser employs a disciplined approach, driven primarily by proprietary research regarding prevailing interest rates, economic fundamentals at both the national and state levels and in-depth credit research conducted by the Adviser’s investment staff. The Fund may invest in securities of issuers that are in default or that are in bankruptcy. Security selection The Adviser anticipates that the Fund’s investments in revenue obligations will emphasize municipal securities backed by revenue from essential services, such as hospitals and healthcare, power generation, transportation, education and housing. The Adviser considers both broad economic and issuer specific factors in selecting a portfolio designed to achieve the Fund’s investment objectives. In assessing the appropriate maturity, rating and sector weightings of the Fund’s portfolio, the Adviser considers a variety of factors that are expected to influence economic activity and interest rates. These factors include fundamental economic indicators such as the rates of economic growth and inflation, Federal Reserve monetary policy and the relative value of the U.S. dollar compared to other currencies. Once the Adviser determines the preferable portfolio characteristics, the Adviser selects individual securities based upon the terms of the securities (such as yields compared to U.S. Treasuries or comparable issues), liquidity and rating, sector and issuer diversification. The Adviser attempts to identify investment grade and below investment grade municipal securities that are trading at attractive valuations relative Table of Contents to the Adviser’s evaluation of the issuer’s credit worthiness and, with respect to private activity bonds, the profit potential of the corporation from which the revenue supporting the bonds is derived. The Adviser’s overall investment approach is both top-down and bottom-up. The Adviser first seeks to identify the sectors or regions of the municipal bond market that present the best relative value opportunities, and then bases the Fund’s overall sector and regional weightings on that determination. Once the Adviser establishes the overall regional and sector weightings, the Adviser focuses on selecting those securities within each sector or region that meet its fundamental criteria. In determining sector weightings, the Fund’s portfolio management team also maintains frequent contact with the Adviser’s investment professionals who follow U.S. equities and those who focus on corporate fixed income investments. In many cases, the Adviser will augment its municipal bond credit research and security selection processes with equity research analysis. The Adviser has a fundamental bias towards long-term security selection, rather than engaging in frequent “market timing” or short-term trading. There can be no assurance that this process will be successful. Duration management The Adviser actively manages the duration of the Fund’s portfolio of municipal securities based primarily on the Adviser’s outlook for interest rates. The Adviser considers economic trends, Federal Reserve Board actions and capital markets activity, among other factors, in developing its outlook for interest rates. The Adviser believes that maintaining duration at an appropriate level offers the potential for above-average returns while limiting the risks of interest rate volatility. Duration seeks to measure the price sensitivity of a fixed income security to changes in interest rates. Unlike maturity, duration takes into account interest payments that occur throughout the course of holding the bond. The longer a portfolio’s duration, the more sensitive it will be to changes in interest rates. For example, if the Fund has a two year duration, then all other things being equal, the Fund will decrease in value by two percent if interest rates rise one percent. The Adviser modifies the average duration of the Fund’s portfolio in response to market conditions. The Adviser may employ certain strategies to reduce the Fund’s interest rate sensitivity, including investments in interest rate swap or cap transactions. There is no assurance that the Adviser will do so or that such strategies will be successful. Credit management The Fund may invest in municipal securities with a broad range of credit ratings, including both investment grade and below investment grade municipal securities. At least 40% of the Fund’s portfolio of municipal Table of Contents securities will be rated investment grade at the time of acquisition (that is, rated at least Baa by Moody’s Investors Service, Inc. (“Moody’s”) or BBB by Standard & Poor’s Ratings Group (“S&P”) or, if unrated, determined by the Adviser to be of comparable credit quality). No more than 60% of the Fund’s portfolio of municipal securities will be rated below investment grade at the time of acquisition (that is, Ba or lower by Moody’s or BB or lower by S&P or, if unrated, determined by the Adviser to be of comparable credit quality). No more than 10% of the Fund’s portfolio of municipal securities will be rated at the time of acquisition B or lower by Moody’s and S&P or, if unrated, determined by the Fund’s investment adviser to be of comparable credit quality. Municipal securities of below investment grade quality are regarded as having predominantly speculative characteristics with respect to the issuer’s capacity to pay interest and repay principal and are commonly referred to as “junk bonds” or “high yield securities.” They involve greater risk of loss, are subject to greater price volatility and are less liquid, especially during periods of economic uncertainty or change, than higher rated municipal securities. Municipal securities rated Ba or BB may face significant ongoing uncertainties or exposure to adverse business, financial or economic conditions that could lead to the issuer being unable to meet its financial commitments. The protection of interest and principal payments may be moderate and not well-safeguarded during both good and bad times. Municipal securities rated B generally lack the characteristics of a desirable investment. Assurance of interest and principal payments or of maintenance of other terms of the contract over any long period of time may be low, and such municipal securities are more vulnerable to nonpayment than obligations rated BB. Adverse business, financial or economic conditions will likely impair the issuer’s capacity or willingness to meet its financial commitment on municipal securities. Municipal securities rated Caa, Ca or C by Moody’s or CCC, CC or C by S&P are generally speculative to a high degree. These municipal securities may be in default or they may present elements of danger with respect to principal or interest. Generally, the issuers are dependent upon favorable business, financial and economic conditions to meet their financial commitments on such municipal securities. The Fund may invest in high yield municipal securities of any rating, including securities that are in default at the time of purchase. The Adviser determines the allocation of the Fund’s assets among securities with different credit ratings depending upon the Adviser’s evaluation of factors such as the spread between the yields on municipal securities of different ratings, changes in default rates, general economic conditions and the outlook for fiscal issues facing municipal issuers. Generally, as the spread between the yield on investment grade and non-investment grade securities widens, the Adviser will allocate a greater Table of Contents portion of the Fund’s assets to non-investment grade municipal securities. If the spread based on relative credit quality narrows, the Adviser may determine that high yield municipal securities no longer offer a sufficient risk premium and increase the average credit quality of the Fund’s portfolio. As the economy strengthens and the default risk lessens, the Adviser may increase the Fund’s investment in lower quality, non-investment grade securities. The Adviser also seeks to mitigate the risks of investing in below investment grade securities through a disciplined approach, driven primarily by fundamental research to assess an issuer’s credit quality and the relative value of its securities. Moreover, with respect to below investment grade securities that are private activity bonds, the Adviser intends to emphasize securities that are backed by revenue from publicly traded companies. The Adviser believes that this focus offers the potential for an informational advantage due to the substantial reporting requirements of public companies. With respect to investments in below investment grade private activity bonds, the Adviser also seeks to leverage its corporate credit research capabilities by selecting securities for the Fund payable by revenue derived from issuers followed by its staff focusing on below investment grade corporate issuers. The Adviser believes that a prudent blend of investment grade and non-investment grade municipal securities offers investors the opportunity for high current yield without undue credit risk. High yield mu nic | |||||
Risk Factors [Table Text Block] | PRINCIPAL RISKS General. The Fund is a closed-end management investment company designed primarily as a long-term investment and not as a trading tool. The Fund is not a complete investment program and should be considered only as an addition to an investor’s existing portfolio of investments. Because the Fund may invest substantially in high yield debt securities, an investment in the Fund’s shares is speculative in that it involves a high degree of risk. Due to uncertainty inherent in all investments, there can be no assurance that the Fund will achieve its investment objective. Instruments in which the Fund invests may only have limited liquidity, or may be illiquid. Market price of Common Shares. Common shares of closed-end funds frequently trade at a price lower than their net asset value. This is commonly referred to as “trading at a discount.” This characteristic of shares of closed-end funds is a risk separate and distinct from the risk that the Fund’s net asset value may decrease. Both long and short-term investors, including investors who sell their shares within a relatively short period after purchase, will be exposed to this risk. The Fund is designed primarily for long-term investors and should not be considered a vehicle for trading purposes. Whether investors will realize a gain or loss upon the sale of the Fund’s Common Shares will depend upon whether the market value of the shares at the time of sale is above or below the price the investor paid, taking into account transaction costs, for the shares and is not directly dependent upon the Fund’s net asset value. Because the market value of the Fund’s shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors beyond the control of the Fund, the Fund cannot predict whether its Common Shares will trade at, below or above net asset value, or below or above the offering price for the shares. Market risk. The market prices of securities or other assets held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, political instability, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues, weather or climate events, armed conflict, market disruptions caused by tariffs, trade disputes, sanctions or other government actions, or other factors or adverse investor sentiment. If th e m Table of Contents condition or other event affecting a single issuer or market may adversely impact securities markets as a whole. Changes in market conditions may not have the same impact on all types of securities. The value of securities may also fall due to specific conditions that affect a particular sector of the securities market or a particular issuer. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars, terror attacks and economic sanctions); measures to address budget deficits; downgrading of sovereign debt; changes in oil and commodity prices; dramatic changes in currency exchange rates; global pandemics; and public sentiment. The long-term impact of the COVID-19 pandemic and its subsequent variants on economies, markets, industries and individual issuers, are not known. Some sectors of the economy and individual issuers have experienced or may experience particularly large losses. Periods of extreme volatility in the financial markets; reduced liquidity of many instruments; increased government debt, inflation and disruptions to supply chains, consumer demand and employee availability, may continue for some time. Raising the ceiling on U.S. government debt has become increasingly politicized. Any failure to increase the total amount that the U.S. government is authorized to borrow could lead to a default on U.S. government obligations, with unpredictable consequences for economies and markets in the U.S. and elsewhere. Inflation and interest rates have increased and may rise further. These circumstances could adversely affect the value and liquidity of the Fund's investments, and negatively impact the Fund's performance. In addition, inflation, rising interest rates, global supply chain disruptions and other market events could adversely affect the companies or issuers in which the Fund invests. Following Russia’s invasion of Ukraine, Russian securities lost all, or nearly all, their market value. Other securities or markets could be similarly affected by past or future political, geopolitical or other events or conditions. Governments and central banks, including the U.S. Federal Reserve, have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The consequences of high public debt, including its future impact on the economy and securities markets, may not be known for some time. U.S. Federal Reserve Table of Contents or other U.S. or non-U.S. governmental or central bank actions, including increases or decreases in interest rates, or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the Fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and these and other events affecting global markets, such as the United Kingdom’s exit from the European Union (or Brexit), potential trade imbalances with China or other countries, or sanctions or other government actions against Russia, other nations or individuals or companies (or their countermeasures), may contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the implications for market participants, may not be fully known for some time. The U.S. and other countries are periodically involved in disputes over trade and other matters, which may result in tariffs, investment restrictions and adverse impacts on affected companies and securities. For example, the U.S. has imposed tariffs and other trade barriers on Chinese exports, has restricted sales of certain categories of goods to China, and has established barriers to investments in China. Trade disputes may adversely affect the economies of the U.S. and its trading partners, as well as companies directly or indirectly affected and financial markets generally. The U.S. government has prohibited U.S. persons, such as the Fund, from investing in Chinese companies designated as related to the Chinese military. These and possible future restrictions could limit the Fund’s opportunities for investment and require the sale of securities at a loss or make them illiquid. The Chinese government is involved in a longstanding dispute with Taiwan that has included threats of invasion. If the political climate between the U.S. and China does not improve or continues to deteriorate, if China were to attempt unification of Taiwan by force, or if other geopolitical conflicts develop or get worse, economies, markets and individual securities may be severely affected both regionally and globally, and the value of the Fund’s assets may go down. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, armed conflict such as between Russia and Ukraine or in the Middle East, terrorism, natural disasters, infectious illness or public health issues, cybersecurity events, supply chain disruptions, sanctions against Russia, other nations or individuals or companies and possible countermeasures, and other circumstances in one country or region could have profound impacts on other countries or regions and on global economies or markets. As a result, whether or not the Fund invests in securities of issuers located in or with significant exposure to the countries Table of Contents or regions directly affected, the value and liquidity of the Fund’s investments may be negatively affected. The Fund may experience a substantial or complete loss on any security or derivative position. High yield or “junk” bond risk. Debt securities that are below investment grade, called “junk bonds,” are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default. Interest rate risk. The market prices of the Fund's fixed income securities may fluctuate significantly when interest rates change. The value of your investment will generally go down when interest rates rise. A rise in rates tends to have a greater impact on the prices of longer term or duration securities. For example, if interest rates increase by 1%, the value of a Fund’s portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. In recent years interest rates and credit spreads in the U.S. have been at historic lows. The U.S. Federal Reserve has raised certain interest rates, and interest rates may continue to go up. A general rise in interest rates could adversely affect the price and liquidity of fixed income securities. The maturity of a security may be significantly longer than its effective duration. A security’s maturity and other features may be more relevant than its effective duration in determining the security’s sensitivity to other factors affecting the issuer or markets generally, such as changes in credit quality or in the yield premium that the market may establish for certain types of securities (sometimes called “credit spread”). In general, the longer its maturity the more a security may be susceptible to these factors. When the credit spread for a fixed income security goes up, or “widens,” the value of the security will generally go down. Rising interest rates can lead to increased default rates, as issuers of floating rate securities find themselves faced with higher payments. Unlike fixed rate securities, floating rate securities generally will not increase in value if interest rates decline. Changes in in te Credit risk. If an issuer or guarantor of a security held by the Fund or a counterparty to a financial contract with the Fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline. Changes in actual or perceived creditworthiness may occur quickly. Table of Contents The Fund could be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty. Prepayment or call risk. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the Fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The Fund also may lose any premium it paid on the security. Extension risk. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security’s duration and reduce the value of the security. Risk of illiquid investments. Certain securities and derivatives held by the Fund may be impossible or difficult to purchase, sell or unwind. Illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in an environment of rising interest rates or widening credit spreads. During times of market turmoil, there have been, and may be, no buyers or sellers for securities in entire asset classes. If the Fund is forced to sell an illiquid asset or unwind a derivatives position, the Fund may suffer a substantial loss or may not be able to sell at all. Portfolio selection risk. The Adviser’s judgment about the quality, relative yield, relative value or market trends affecting a particular sector or region, market segment, security, industry or about interest rates or other market factors may prove to be incorrect or may not produce the desired results, or there may be imperfections, errors or limitations in the models, tools and information used by the Adviser. Municipal securities risk. The municipal bond market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Liquidity can be reduced unpredictably in response to overall economic conditions or credit tightening. Issuers of municipal securities tend to derive a significant portion of their revenue fr om Table of Contents payments. Adverse conditions and developments in those sectors can result in lower revenues to issuers of municipal securities, potentially resulting in defaults, and can also have an adverse effect on the broader municipal securities market. To the extent the Fund invests significantly in a single state, or in securities the payments on which are dependent upon a single project or source of revenues, or that relate to a sector or industry, including health care facilities, education, special revenues and housing, the Fund will be more susceptible to associated risks and developments. There may be less public information available on municipal issuers or projects than other issuers, and valuing municipal securities may be more difficult. In addition, the secondary market for municipal securities is less well developed and liquid than other markets, and dealers may be less willing to offer and sell municipal securities in times of market turbulence. Changes in the financial condition of one or more individual municipal issuers (or one or more insurers of municipal issuers), or one or more defaults by municipal issuers or insurers, can adversely affect liquidity and valuations in the overall market for municipal securities. The value of municipal securities can also be adversely affected by regulatory and political developments affecting the ability of municipal issuers to pay interest or repay principal, actual or anticipated tax law changes or other legislative actions, and by uncertainties and public perceptions concerning these and other factors. Municipal securities may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. Financial difficulties of municipal issuers may continue or get worse, particularly in the event of political, economic or market turmoil or a recession. The rate of interest paid on municipal securities normally is lower than the rate of interest paid on fully taxable securities. Some municipal securities, such as general obligation issues, are backed by the issuer’s taxing authority, while other municipal securities, such as revenue issues, are backed only by revenues from certain facilities or other sources and not by the issuer itself. The payment of principal and interest on private activity and industrial development revenue bonds is solely dependent on the ability of the facility’s user to meet its financial obligations and the pledge, if any, of the facility or other property as security for payment. The municipal market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Taxable investment risk. Although distributions of interest income from the Fund’s tax-exempt securities are generally exempt from regular federal income tax, distributions from other sources, including capital gain distributions, and any gains on the sale of your shares are not. In addition, Table of Contents the interest on the Fund’s municipal securities could become subject to regular federal income tax or the AMT due to noncompliant conduct by issuers, unfavorable legislation or litigation, or adverse interpretations by regulatory authorities. You should consult a tax adviser about whether the AMT applies to you and about state and local taxes on your Fund distributions. Risks of subordinated securities. A holder of securities that are subordinated or “junior” to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities than more senior securities. U.S. Treasury obligations risk. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s investments in obligations issued by the U.S. Treasury to decline. U.S. government agency obligations risk. The Fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as the Federal National Mortgage Association (FNMA), the Federal Home Loan Mortgage Corporation (FHLMC) and the Federal Home Loan Banks (FHLBs), although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future. Mortgage-related and asset-backed securities risk. The value of mortgage-related securities, including commercial mortgage-backed securities, collateralized mortgage-backed securities, credit risk transfer securities, and asset-backed securities will be influenced by factors affecting the assets underlying such securities. As a result, during periods Table of Contents of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to interest rate, prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments offered by non-governmental issuers and those that include so-called “sub-prime” mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the Fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss. Risks of investing in collateralized debt obligations. Investment in a collateralized debt obligation (CDO) is subject to the credit, subordination, interest rate, valuation, prepayment, extension and other risks of the obligations underlying the CDO and the tranche of the CDO in which the Fund invests. CDOs are subject to liquidity risk. Synthetic CDOs are also subject to the risks of investing in derivatives, such as credit default swaps, and leverage risk. Risks of instruments that allow for balloon payments or negative amortization payments. Certain debt instruments allow for balloon payments or negative amortization payments.Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan. Risks of zero coupon bonds, payment in kind, deferred and contingent payment securities. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the Fund receives no periodic cash payments on such securities, the Fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the Fund to distribute to stockholders. Such distributions may be taxable when distributed to stockholders. Derivatives risk . Using swaps, forward foreign currency exchange contracts, bond and interest rate futures and other derivatives can increase Table of Contents Fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the Fund. Using derivatives may increase the volatility of the Fund’s net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the Fund. Some derivatives have the potential for unlimited loss, regardless of the size of the Fund’s initial investment. Derivatives are generally subject to the risks applicable to the assets, rates, indices or other indicators underlying the derivative. Changes in a derivative’s value may not correlate well with the referenced asset or metric. The Fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the Fund. Use of derivatives may have different tax consequences for the Fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to stockholders. The U.S. government and foreign governments have adopted and implemented or are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets. Synthetic municipal securities risk. The tax-exempt character of the interest paid on tender option bonds, bond receipts and similar synthetic municipal securities, a type of derivative instrument, is based on the tax-exempt income stream from the collateral. In addition to the risks of investing in mu Risks of investing in inverse floating rate obligations. The interest rate on inverse floating rate obligations will generally decrease as short-term interest rates increase, and increase as short-term rates decrease. Due to their leveraged structure, the sensitivity of the market value of an inverse floating rate obligation to changes in interest rates is generally greater than a comparable long-term bond issued by the same issuer and with similar credit quality, redemption and maturity provisions. Inverse floating rate obligations may be volatile and involve leverage risk. Credit default swap risk. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the Fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the Fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is Table of Contents a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade. Structured securities risk. Structured securities may behave in ways not anticipated by the Fund, or they may not receive the tax, accounting or regulatory treatment anticipated by the Fund. Leveraging risk. The value of your investment may be more volatile and other risks tend to be compounded if the Fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the Fund’s underlying assets and creates a risk of loss of value on a larger pool of assets than the Fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the Fund to liquidate positions when it may not be advantageous to do so. New derivatives regulations require the Fund, to the extent it uses derivatives to a material extent, to, among other things, comply with certain overall limits on leverage. These regulations may limit the ability of the Fund to pursue its investment strategies and may not be effective to mitigate the Fund’s risk of loss from derivatives. The Fund may use financial leverage on an ongoing basis for investment purposes by issuing preferred shares. The fees and expenses attributed to leverage, including any increase in the management fees, will be borne by holders of common shares. Since the Adviser’s fee is based on a percentage of the Fund’s managed assets, its fee will be higher if the Fund is leveraged, and the Adviser will thus have an incentive to leverage the Fund. Repurchase agreement risk. In the event that the other party to a repurchase agreement defaults on its obligations, the Fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the Fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction. Market segment risk. To the extent the Fund emphasizes, from time to time, investments in a market segment, the Fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus. Valuation risk. Nearly all of the Fund's investments are valued using a fair value methodology. The sales price the Fund could receive for any particular portfolio investment may differ from the Fund’s valuation of the investment, particularly for illiquid securities and securities that trade in Table of Contents thin or volatile markets. These differences may increase significantly and affect Fund investments more broadly during periods of market volatility. The ability to value the Fund’s investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers. Cybersecurity risk. Cybersecurity failures by and breaches of the Fund’s Adviser, transfer agent, custodian, Fund accounting agent or other service providers may disrupt Fund operations, interfere with the Fund’s ability to calculate its NAV, prevent Fund stockholders from purchasing or selling shares or receiving distributions or receiving timely information regarding the Fund or their investment in the Fund, cause loss of or unauthorized access to private stockholder information, and result in financial losses to the Fund and its stockholders, regulatory fines, penalties, reputational damage, or additional compliance costs. New ways to carry out cyber attacks continue to develop. Therefore, there is a chance that some risks have not been identified or prepared for, or that an attack may not be detected, which puts limitations on the Fund’s ability to plan for or respond to a cyber attack. Cash management risk. The value of the investments held by the Fund for cash management or temporary defensive purposes may be affected by market risks, changing interest rates and by changes in credit ratings of the investments. To the extent that the Fund has any uninvested cash, the Fund would be subject to credit risk with respect to the depository institution holding the cash. If the Fund holds cash uninvested, the Fund will not earn income on the cash and the Fund’s yield will go down. During such periods, it may be more difficult for the Fund to achieve its investment objective. Anti-takeover provisions. The Fund’s Charter and Bylaws include provisions that are designed to limit the ability of other entities or persons to acquire control of the Fund for short-term objectives, including by converting the Fund to open-end status or changing the composition of the Board, that may be detrimental to the Fund's ability to achieve its primary investment objective of seeking to provide its common stockholders with a high level of current income exempt from regular federal income tax. These provisions include staggered terms of service for the Directors, advance notice requirements for stockholder proposals, and super-majority voting requirements for certain transactions with affiliates, open-ending the Fund or a merger, liquidation, asset sale or similar transaction. The Fund’s Bylaws also contain a provision providing that the Board of Directors has adopted a resolution to opt in the Fund to the provisions of the Maryland Control Share Acquisition Act (“MCSAA”). Such provisions may limit the ability of stockholders to sell their shares at a premium over prevailing Table of Contents market prices by discouraging a third party from seeking to obtain control of the Fund. There can be no assurance, however, that such provisions will be sufficient to deter activist investors that seek to cause the Fund to take actions that may not be aligned with the interests of long-term stockholders. Furthermore, the law is uncertain on the use of control share provisions. Certain courts have found that control s h | |||||
Effects of Leverage [Text Block] | Effects of Leverage The following table is furnished in response to requirement s The assumed investment portfolio returns in the table below are hypothetical figures and are not necessarily indicative of the investment portfolio returns experienced or expected to be experienced by the Fund. Your actual returns may be greater or less than those appearing below. In addition, the actual dividend rate payable on the preferred shares by the Fund may vary frequently and may be significantly higher or lower than the rate used for the example below. Preferred shares as a percentage of total managed assets (including assets attributable to preferred shares) 18.51% Annual effective dividend rate payable by Fund on preferred shares 5.74% Annual return Fund portfolio must experience (net of expenses) to cover dividend rate on preferred shares 1.06% Common share total return for (10.00)% assumed portfolio total return (13.58)% Common share total return for (5.00)% assumed portfolio total return (7.44)% Common share total return for 0.00% assumed portfolio total return (1.30)% Common share total return for 5.00% assumed portfolio total return 4.83% Common share total return for 10.00% assumed portfolio total return 10.97% | |||||
Annual Interest Rate [Percent] | 5.74% | |||||
Annual Coverage Return Rate [Percent] | 1.06% | |||||
Return at Minus Ten [Percent] | (13.58%) | |||||
Return at Minus Five [Percent] | (7.44%) | |||||
Return at Zero [Percent] | (1.30%) | |||||
Return at Plus Five [Percent] | 4.83% | |||||
Return at Plus Ten [Percent] | 10.97% | |||||
Effects of Leverage, Purpose [Text Block] | The following table is furnished in response to requirement s | |||||
Share Price [Table Text Block] | Prices and Distributions | 3/31/24 Market Value per Common Share ^ 3/31/24 3/31/23 Market Value $ $ Discount (11.41)% (12.35)% Net Asset Value per Common Share ^ 3/31/24 3/31/23 Net Asset Value $9.20 $9.39 Distributions per Common Share: 4/1/23 - 3/31/24 Net Investment Short-Term Long-Term 4/1/23 – 3/31/24 $0.3480 $— $— Yields 3/31/24 3/31/23 30-Day SEC Yield 3.31% 3.28% The data shown above represents past performance, which is no guarantee of future results. ^ Net asset value and market value are published in Barron’s The Wall Street Journal The New York Times | |||||
Share Price | [6] | $ 8.15 | 8.23 | |||
NAV Per Share | [6] | $ 9.2 | $ 9.39 | |||
Latest Premium (Discount) to NAV [Percent] | [6] | (11.41%) | (12.35%) | |||
General [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | General. The Fund is a closed-end management investment company designed primarily as a long-term investment and not as a trading tool. The Fund is not a complete investment program and should be considered only as an addition to an investor’s existing portfolio of investments. Because the Fund may invest substantially in high yield debt securities, an investment in the Fund’s shares is speculative in that it involves a high degree of risk. Due to uncertainty inherent in all investments, there can be no assurance that the Fund will achieve its investment objective. Instruments in which the Fund invests may only have limited liquidity, or may be illiquid. | |||||
Market price of Common Shares [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Market price of Common Shares. Common shares of closed-end funds frequently trade at a price lower than their net asset value. This is commonly referred to as “trading at a discount.” This characteristic of shares of closed-end funds is a risk separate and distinct from the risk that the Fund’s net asset value may decrease. Both long and short-term investors, including investors who sell their shares within a relatively short period after purchase, will be exposed to this risk. The Fund is designed primarily for long-term investors and should not be considered a vehicle for trading purposes. Whether investors will realize a gain or loss upon the sale of the Fund’s Common Shares will depend upon whether the market value of the shares at the time of sale is above or below the price the investor paid, taking into account transaction costs, for the shares and is not directly dependent upon the Fund’s net asset value. Because the market value of the Fund’s shares will be determined by factors such as the relative demand for and supply of the shares in the market, general market conditions and other factors beyond the control of the Fund, the Fund cannot predict whether its Common Shares will trade at, below or above net asset value, or below or above the offering price for the shares. | |||||
Market risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Market risk. The market prices of securities or other assets held by the Fund may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic, political, or regulatory conditions, political instability, recessions, inflation, changes in interest or currency rates, lack of liquidity in the bond markets, the spread of infectious illness or other public health issues, weather or climate events, armed conflict, market disruptions caused by tariffs, trade disputes, sanctions or other government actions, or other factors or adverse investor sentiment. If th e m Table of Contents condition or other event affecting a single issuer or market may adversely impact securities markets as a whole. Changes in market conditions may not have the same impact on all types of securities. The value of securities may also fall due to specific conditions that affect a particular sector of the securities market or a particular issuer. In the past decade, financial markets throughout the world have experienced increased volatility, depressed valuations, decreased liquidity and heightened uncertainty. Governmental and non-governmental issuers have defaulted on, or been forced to restructure, their debts. These conditions may continue, recur, worsen or spread. Events that have contributed to these market conditions include, but are not limited to, major cybersecurity events; geopolitical events (including wars, terror attacks and economic sanctions); measures to address budget deficits; downgrading of sovereign debt; changes in oil and commodity prices; dramatic changes in currency exchange rates; global pandemics; and public sentiment. The long-term impact of the COVID-19 pandemic and its subsequent variants on economies, markets, industries and individual issuers, are not known. Some sectors of the economy and individual issuers have experienced or may experience particularly large losses. Periods of extreme volatility in the financial markets; reduced liquidity of many instruments; increased government debt, inflation and disruptions to supply chains, consumer demand and employee availability, may continue for some time. Raising the ceiling on U.S. government debt has become increasingly politicized. Any failure to increase the total amount that the U.S. government is authorized to borrow could lead to a default on U.S. government obligations, with unpredictable consequences for economies and markets in the U.S. and elsewhere. Inflation and interest rates have increased and may rise further. These circumstances could adversely affect the value and liquidity of the Fund's investments, and negatively impact the Fund's performance. In addition, inflation, rising interest rates, global supply chain disruptions and other market events could adversely affect the companies or issuers in which the Fund invests. Following Russia’s invasion of Ukraine, Russian securities lost all, or nearly all, their market value. Other securities or markets could be similarly affected by past or future political, geopolitical or other events or conditions. Governments and central banks, including the U.S. Federal Reserve, have taken extraordinary and unprecedented actions to support local and global economies and the financial markets. These actions have resulted in significant expansion of public debt, including in the U.S. The consequences of high public debt, including its future impact on the economy and securities markets, may not be known for some time. U.S. Federal Reserve Table of Contents or other U.S. or non-U.S. governmental or central bank actions, including increases or decreases in interest rates, or contrary actions by different governments, could negatively affect financial markets generally, increase market volatility and reduce the value and liquidity of securities in which the Fund invests. Policy and legislative changes in the U.S. and in other countries are affecting many aspects of financial regulation, and these and other events affecting global markets, such as the United Kingdom’s exit from the European Union (or Brexit), potential trade imbalances with China or other countries, or sanctions or other government actions against Russia, other nations or individuals or companies (or their countermeasures), may contribute to decreased liquidity and increased volatility in the financial markets. The impact of these changes on the markets, and the implications for market participants, may not be fully known for some time. The U.S. and other countries are periodically involved in disputes over trade and other matters, which may result in tariffs, investment restrictions and adverse impacts on affected companies and securities. For example, the U.S. has imposed tariffs and other trade barriers on Chinese exports, has restricted sales of certain categories of goods to China, and has established barriers to investments in China. Trade disputes may adversely affect the economies of the U.S. and its trading partners, as well as companies directly or indirectly affected and financial markets generally. The U.S. government has prohibited U.S. persons, such as the Fund, from investing in Chinese companies designated as related to the Chinese military. These and possible future restrictions could limit the Fund’s opportunities for investment and require the sale of securities at a loss or make them illiquid. The Chinese government is involved in a longstanding dispute with Taiwan that has included threats of invasion. If the political climate between the U.S. and China does not improve or continues to deteriorate, if China were to attempt unification of Taiwan by force, or if other geopolitical conflicts develop or get worse, economies, markets and individual securities may be severely affected both regionally and globally, and the value of the Fund’s assets may go down. Economies and financial markets throughout the world are increasingly interconnected. Economic, financial or political events, trading and tariff arrangements, armed conflict such as between Russia and Ukraine or in the Middle East, terrorism, natural disasters, infectious illness or public health issues, cybersecurity events, supply chain disruptions, sanctions against Russia, other nations or individuals or companies and possible countermeasures, and other circumstances in one country or region could have profound impacts on other countries or regions and on global economies or markets. As a result, whether or not the Fund invests in securities of issuers located in or with significant exposure to the countries Table of Contents or regions directly affected, the value and liquidity of the Fund’s investments may be negatively affected. The Fund may experience a substantial or complete loss on any security or derivative position. | |||||
High yield or junk bond risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | High yield or “junk” bond risk. Debt securities that are below investment grade, called “junk bonds,” are speculative, have a higher risk of default or are already in default, tend to be less liquid and are more difficult to value than higher grade securities. Junk bonds tend to be volatile and more susceptible to adverse events and negative sentiments. These risks are more pronounced for securities that are already in default. | |||||
Credit Risks [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Credit risk. If an issuer or guarantor of a security held by the Fund or a counterparty to a financial contract with the Fund defaults on its obligation to pay principal and/or interest, has its credit rating downgraded or is perceived to be less creditworthy, or the credit quality or value of any underlying assets declines, the value of your investment will typically decline. Changes in actual or perceived creditworthiness may occur quickly. Table of Contents The Fund could be delayed or hindered in its enforcement of rights against an issuer, guarantor or counterparty. | |||||
Prepayment or call risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Prepayment or call risk. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right. If this happens, the Fund will not benefit from the rise in market price that normally accompanies a decline in interest rates, and will be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The Fund also may lose any premium it paid on the security. | |||||
Extension risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Extension risk. During periods of rising interest rates, the average life of certain types of securities may be extended because of slower than expected principal payments. This may lock in a below market interest rate, increase the security’s duration and reduce the value of the security. | |||||
Risk of illiquid investments [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risk of illiquid investments. Certain securities and derivatives held by the Fund may be impossible or difficult to purchase, sell or unwind. Illiquid securities and derivatives also may be difficult to value. Liquidity risk may be magnified in an environment of rising interest rates or widening credit spreads. During times of market turmoil, there have been, and may be, no buyers or sellers for securities in entire asset classes. If the Fund is forced to sell an illiquid asset or unwind a derivatives position, the Fund may suffer a substantial loss or may not be able to sell at all. | |||||
Portfolio selection risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Portfolio selection risk. The Adviser’s judgment about the quality, relative yield, relative value or market trends affecting a particular sector or region, market segment, security, industry or about interest rates or other market factors may prove to be incorrect or may not produce the desired results, or there may be imperfections, errors or limitations in the models, tools and information used by the Adviser. | |||||
Municipal securities risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Municipal securities risk. The municipal bond market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. Liquidity can be reduced unpredictably in response to overall economic conditions or credit tightening. Issuers of municipal securities tend to derive a significant portion of their revenue fr om Table of Contents payments. Adverse conditions and developments in those sectors can result in lower revenues to issuers of municipal securities, potentially resulting in defaults, and can also have an adverse effect on the broader municipal securities market. To the extent the Fund invests significantly in a single state, or in securities the payments on which are dependent upon a single project or source of revenues, or that relate to a sector or industry, including health care facilities, education, special revenues and housing, the Fund will be more susceptible to associated risks and developments. There may be less public information available on municipal issuers or projects than other issuers, and valuing municipal securities may be more difficult. In addition, the secondary market for municipal securities is less well developed and liquid than other markets, and dealers may be less willing to offer and sell municipal securities in times of market turbulence. Changes in the financial condition of one or more individual municipal issuers (or one or more insurers of municipal issuers), or one or more defaults by municipal issuers or insurers, can adversely affect liquidity and valuations in the overall market for municipal securities. The value of municipal securities can also be adversely affected by regulatory and political developments affecting the ability of municipal issuers to pay interest or repay principal, actual or anticipated tax law changes or other legislative actions, and by uncertainties and public perceptions concerning these and other factors. Municipal securities may be more susceptible to downgrades or defaults during recessions or similar periods of economic stress. Financial difficulties of municipal issuers may continue or get worse, particularly in the event of political, economic or market turmoil or a recession. The rate of interest paid on municipal securities normally is lower than the rate of interest paid on fully taxable securities. Some municipal securities, such as general obligation issues, are backed by the issuer’s taxing authority, while other municipal securities, such as revenue issues, are backed only by revenues from certain facilities or other sources and not by the issuer itself. The payment of principal and interest on private activity and industrial development revenue bonds is solely dependent on the ability of the facility’s user to meet its financial obligations and the pledge, if any, of the facility or other property as security for payment. The municipal market can be susceptible to unusual volatility, particularly for lower-rated and unrated securities. | |||||
Taxable investment risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Taxable investment risk. Although distributions of interest income from the Fund’s tax-exempt securities are generally exempt from regular federal income tax, distributions from other sources, including capital gain distributions, and any gains on the sale of your shares are not. In addition, Table of Contents the interest on the Fund’s municipal securities could become subject to regular federal income tax or the AMT due to noncompliant conduct by issuers, unfavorable legislation or litigation, or adverse interpretations by regulatory authorities. You should consult a tax adviser about whether the AMT applies to you and about state and local taxes on your Fund distributions. | |||||
Risks of subordinated securities [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risks of subordinated securities. A holder of securities that are subordinated or “junior” to more senior securities of an issuer is entitled to payment after holders of more senior securities of the issuer. Subordinated securities are more likely to suffer a credit loss than non-subordinated securities of the same issuer, any loss incurred by the subordinated securities is likely to be proportionately greater, and any recovery of interest or principal may take more time. As a result, even a perceived decline in creditworthiness of the issuer is likely to have a greater impact on subordinated securities than more senior securities. | |||||
U.S. Treasury obligations risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | U.S. Treasury obligations risk. The market value of direct obligations of the U.S. Treasury may vary due to changes in interest rates. In addition, changes to the financial condition or credit rating of the U.S. government may cause the value of the Fund’s investments in obligations issued by the U.S. Treasury to decline. | |||||
U.S. government agency obligations risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | U.S. government agency obligations risk. The Fund invests in obligations issued by agencies and instrumentalities of the U.S. government. Government-sponsored entities such as the Federal National Mortgage Association (FNMA), the Federal Home Loan Mortgage Corporation (FHLMC) and the Federal Home Loan Banks (FHLBs), although chartered or sponsored by Congress, are not funded by congressional appropriations and the debt and mortgage-backed securities issued by them are neither guaranteed nor issued by the U.S. government. The maximum potential liability of the issuers of some U.S. government obligations may greatly exceed their current resources, including any legal right to support from the U.S. government. Such debt and mortgage-backed securities are subject to the risk of default on the payment of interest and/or principal, similar to debt of private issuers. Although the U.S. government has provided financial support to FNMA and FHLMC in the past, there can be no assurance that it will support these or other government-sponsored entities in the future. | |||||
Mortgagerelated and assetbacked securities risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Mortgage-related and asset-backed securities risk. The value of mortgage-related securities, including commercial mortgage-backed securities, collateralized mortgage-backed securities, credit risk transfer securities, and asset-backed securities will be influenced by factors affecting the assets underlying such securities. As a result, during periods Table of Contents of declining asset value, difficult or frozen credit markets, swings in interest rates, or deteriorating economic conditions, mortgage-related and asset-backed securities may decline in value, face valuation difficulties, become more volatile and/or become illiquid. Mortgage-backed securities tend to be more sensitive to changes in interest rate than other types of debt securities. These securities are also subject to interest rate, prepayment and extension risks. Some of these securities may receive little or no collateral protection from the underlying assets and are thus subject to the risk of default. The risk of such defaults is generally higher in the case of mortgage-backed investments offered by non-governmental issuers and those that include so-called “sub-prime” mortgages. The structure of some of these securities may be complex and there may be less available information than for other types of debt securities. Upon the occurrence of certain triggering events or defaults, the Fund may become the holder of underlying assets at a time when those assets may be difficult to sell or may be sold only at a loss. | |||||
Risks of investing in collateralized debt obligations [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risks of investing in collateralized debt obligations. Investment in a collateralized debt obligation (CDO) is subject to the credit, subordination, interest rate, valuation, prepayment, extension and other risks of the obligations underlying the CDO and the tranche of the CDO in which the Fund invests. CDOs are subject to liquidity risk. Synthetic CDOs are also subject to the risks of investing in derivatives, such as credit default swaps, and leverage risk. | |||||
Risks of instruments that allow for balloon payments or negative amortization payments [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risks of instruments that allow for balloon payments or negative amortization payments. Certain debt instruments allow for balloon payments or negative amortization payments.Such instruments permit the borrower to avoid paying currently a portion of the interest accruing on the instrument. While these features make the debt instrument more affordable to the borrower in the near term, they increase the risk that the borrower will be unable to make the resulting higher payment or payments that become due at the maturity of the loan. | |||||
Risks of zero coupon bonds, payment in kind, deferred and contingent payment securities [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risks of zero coupon bonds, payment in kind, deferred and contingent payment securities. These securities may be more speculative and may fluctuate more in value than securities which pay income periodically and in cash. In addition, although the Fund receives no periodic cash payments on such securities, the Fund is deemed for tax purposes to receive income from such securities, which applicable tax rules require the Fund to distribute to stockholders. Such distributions may be taxable when distributed to stockholders. | |||||
Derivatives risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Derivatives risk . Using swaps, forward foreign currency exchange contracts, bond and interest rate futures and other derivatives can increase Table of Contents Fund losses and reduce opportunities for gains when market prices, interest rates or the derivative instruments themselves behave in a way not anticipated by the Fund. Using derivatives may increase the volatility of the Fund’s net asset value and may not provide the result intended. Derivatives may have a leveraging effect on the Fund. Some derivatives have the potential for unlimited loss, regardless of the size of the Fund’s initial investment. Derivatives are generally subject to the risks applicable to the assets, rates, indices or other indicators underlying the derivative. Changes in a derivative’s value may not correlate well with the referenced asset or metric. The Fund also may have to sell assets at inopportune times to satisfy its obligations. Derivatives may be difficult to sell, unwind or value, and the counterparty may default on its obligations to the Fund. Use of derivatives may have different tax consequences for the Fund than an investment in the underlying security, and such differences may affect the amount, timing and character of income distributed to stockholders. The U.S. government and foreign governments have adopted and implemented or are in the process of adopting and implementing regulations governing derivatives markets, including mandatory clearing of certain derivatives, margin and reporting requirements. The ultimate impact of the regulations remains unclear. Additional regulation of derivatives may make them more costly, limit their availability or utility, otherwise adversely affect their performance or disrupt markets. | |||||
Synthetic municipal securities risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Synthetic municipal securities risk. The tax-exempt character of the interest paid on tender option bonds, bond receipts and similar synthetic municipal securities, a type of derivative instrument, is based on the tax-exempt income stream from the collateral. In addition to the risks of investing in mu | |||||
Risks of investing in inverse floating rate obligations [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Risks of investing in inverse floating rate obligations. The interest rate on inverse floating rate obligations will generally decrease as short-term interest rates increase, and increase as short-term rates decrease. Due to their leveraged structure, the sensitivity of the market value of an inverse floating rate obligation to changes in interest rates is generally greater than a comparable long-term bond issued by the same issuer and with similar credit quality, redemption and maturity provisions. Inverse floating rate obligations may be volatile and involve leverage risk. | |||||
Credit default swap risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Credit default swap risk. Credit default swap contracts, a type of derivative instrument, involve special risks and may result in losses to the Fund. Credit default swaps may in some cases be illiquid, and they increase credit risk since the Fund has exposure to the issuer of the referenced obligation and either the counterparty to the credit default swap or, if it is Table of Contents a cleared transaction, the brokerage firm through which the trade was cleared and the clearing organization that is the counterparty to that trade. | |||||
Structured securities risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Structured securities risk. Structured securities may behave in ways not anticipated by the Fund, or they may not receive the tax, accounting or regulatory treatment anticipated by the Fund. | |||||
Leveraging risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Leveraging risk. The value of your investment may be more volatile and other risks tend to be compounded if the Fund borrows or uses derivatives or other investments, such as ETFs, that have embedded leverage. Leverage generally magnifies the effect of any increase or decrease in the value of the Fund’s underlying assets and creates a risk of loss of value on a larger pool of assets than the Fund would otherwise have, potentially resulting in the loss of all assets. Engaging in such transactions may cause the Fund to liquidate positions when it may not be advantageous to do so. New derivatives regulations require the Fund, to the extent it uses derivatives to a material extent, to, among other things, comply with certain overall limits on leverage. These regulations may limit the ability of the Fund to pursue its investment strategies and may not be effective to mitigate the Fund’s risk of loss from derivatives. The Fund may use financial leverage on an ongoing basis for investment purposes by issuing preferred shares. The fees and expenses attributed to leverage, including any increase in the management fees, will be borne by holders of common shares. Since the Adviser’s fee is based on a percentage of the Fund’s managed assets, its fee will be higher if the Fund is leveraged, and the Adviser will thus have an incentive to leverage the Fund. | |||||
Repurchase agreement risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Repurchase agreement risk. In the event that the other party to a repurchase agreement defaults on its obligations, the Fund may encounter delay and incur costs before being able to sell the security. Such a delay may involve loss of interest or a decline in price of the security. In addition, if the Fund is characterized by a court as an unsecured creditor, it would be at risk of losing some or all of the principal and interest involved in the transaction. | |||||
Market segment risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Market segment risk. To the extent the Fund emphasizes, from time to time, investments in a market segment, the Fund will be subject to a greater degree to the risks particular to that segment, and may experience greater market fluctuation than a fund without the same focus. | |||||
Valuation risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Valuation risk. Nearly all of the Fund's investments are valued using a fair value methodology. The sales price the Fund could receive for any particular portfolio investment may differ from the Fund’s valuation of the investment, particularly for illiquid securities and securities that trade in Table of Contents thin or volatile markets. These differences may increase significantly and affect Fund investments more broadly during periods of market volatility. The ability to value the Fund’s investments may also be impacted by technological issues and/or errors by pricing services or other third party service providers. | |||||
Cybersecurity risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Cybersecurity risk. Cybersecurity failures by and breaches of the Fund’s Adviser, transfer agent, custodian, Fund accounting agent or other service providers may disrupt Fund operations, interfere with the Fund’s ability to calculate its NAV, prevent Fund stockholders from purchasing or selling shares or receiving distributions or receiving timely information regarding the Fund or their investment in the Fund, cause loss of or unauthorized access to private stockholder information, and result in financial losses to the Fund and its stockholders, regulatory fines, penalties, reputational damage, or additional compliance costs. New ways to carry out cyber attacks continue to develop. Therefore, there is a chance that some risks have not been identified or prepared for, or that an attack may not be detected, which puts limitations on the Fund’s ability to plan for or respond to a cyber attack. | |||||
Cash management risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Cash management risk. The value of the investments held by the Fund for cash management or temporary defensive purposes may be affected by market risks, changing interest rates and by changes in credit ratings of the investments. To the extent that the Fund has any uninvested cash, the Fund would be subject to credit risk with respect to the depository institution holding the cash. If the Fund holds cash uninvested, the Fund will not earn income on the cash and the Fund’s yield will go down. During such periods, it may be more difficult for the Fund to achieve its investment objective. | |||||
Antitakeover provisions [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Anti-takeover provisions. The Fund’s Charter and Bylaws include provisions that are designed to limit the ability of other entities or persons to acquire control of the Fund for short-term objectives, including by converting the Fund to open-end status or changing the composition of the Board, that may be detrimental to the Fund's ability to achieve its primary investment objective of seeking to provide its common stockholders with a high level of current income exempt from regular federal income tax. These provisions include staggered terms of service for the Directors, advance notice requirements for stockholder proposals, and super-majority voting requirements for certain transactions with affiliates, open-ending the Fund or a merger, liquidation, asset sale or similar transaction. The Fund’s Bylaws also contain a provision providing that the Board of Directors has adopted a resolution to opt in the Fund to the provisions of the Maryland Control Share Acquisition Act (“MCSAA”). Such provisions may limit the ability of stockholders to sell their shares at a premium over prevailing Table of Contents market prices by discouraging a third party from seeking to obtain control of the Fund. There can be no assurance, however, that such provisions will be sufficient to deter activist investors that seek to cause the Fund to take actions that may not be aligned with the interests of long-term stockholders. Furthermore, the law is uncertain on the use of control share provisions. Certain courts have found that control s h | |||||
Interest Rate Risk [Member] | ||||||
General Description of Registrant [Abstract] | ||||||
Risk [Text Block] | Interest rate risk. The market prices of the Fund's fixed income securities may fluctuate significantly when interest rates change. The value of your investment will generally go down when interest rates rise. A rise in rates tends to have a greater impact on the prices of longer term or duration securities. For example, if interest rates increase by 1%, the value of a Fund’s portfolio with a portfolio duration of ten years would be expected to decrease by 10%, all other things being equal. In recent years interest rates and credit spreads in the U.S. have been at historic lows. The U.S. Federal Reserve has raised certain interest rates, and interest rates may continue to go up. A general rise in interest rates could adversely affect the price and liquidity of fixed income securities. The maturity of a security may be significantly longer than its effective duration. A security’s maturity and other features may be more relevant than its effective duration in determining the security’s sensitivity to other factors affecting the issuer or markets generally, such as changes in credit quality or in the yield premium that the market may establish for certain types of securities (sometimes called “credit spread”). In general, the longer its maturity the more a security may be susceptible to these factors. When the credit spread for a fixed income security goes up, or “widens,” the value of the security will generally go down. Rising interest rates can lead to increased default rates, as issuers of floating rate securities find themselves faced with higher payments. Unlike fixed rate securities, floating rate securities generally will not increase in value if interest rates decline. Changes in in te | |||||
Common Share [Member] | ||||||
Capital Stock, Long-Term Debt, and Other Securities [Abstract] | ||||||
Outstanding Security, Authorized [Shares] | 1,000,000,000 | |||||
Outstanding Security, Held [Shares] | 23,914,439 | 23,914,439 | ||||
[1]The Fund issued 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on February 16, 2021.[2]The Fund redeemed 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on November 14, 2022.[3]The Fund redeemed 200 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on September 29, 2022.[4]The Fund redeemed 900 Variable Rate MuniFund Term Preferred Shares, with a liquidation preference of $100,000 per share, on February 29, 2024.[5]Market value is redemption value without an active market.[6]Net asset value and market value are published in Barron’s on Saturday, The Wall Street Journal on Monday and The New York Times on Monday and Saturday. Net asset value and market value are published daily on the Fund’s website at www.amundi.com/us. |