N-2
| N-2 | 12 Months Ended |
| Feb. 29, 2024 | |
| Cover [Abstract] | |
| Entity Central Index Key | 0000884152 |
| Amendment Flag | false |
| Document Type | N-CSR |
| Entity Registrant Name | Invesco Municipal Opportunity Trust |
| General Description of Registrant [Abstract] | |
| Investment Objectives and Practices [Text Block] | Recent Changes The following information is a summary of certain changes made during the Trust’s most recent fiscal year. This information may not reflect all of the changes that have occurred since you purchased the Trust. Changes to Portfolio Managers Effective June 30, 2023, Jim Phillips no longer serves as a portfolio manager of the Trust. Except as noted above, during the Trust’s most recent fiscal year, there were no other changes to the portfolio management of the Trust. Changes to Investment Policies During the Trust’s most recently completed fiscal year, on September 20, 2023, the Board approved the removal of the Trust’s investment policy that restricts the Trust from purchasing securities that are in default or rated in categories lower than B- by S&P Global Ratings (“S&P”) or B3 by Moody’s Investors Service, Inc. (“Moody’s”) or unrated securities of comparable quality. The Trust may invest, under normal market conditions, up to 20% of its respective net assets in municipal securities rated below investment grade or that are unrated but determined by Invesco Advisers to be of comparable quality at the time of purchase. As a result of the investment policy change, the Trust may invest in securities that are in default or rated in categories lower than B- by S&P or B3 by Moody’s or unrated securities of comparable quality as part of the foregoing 20% limitation on below investment grade securities. As a result of the investment policy change, the Trust is more susceptible to high yield debt/below-investment grade risk, and the following risk was added as a principal risk of the Trust. Defaulted Securities Risk Except as noted above, during the Trust’s most recent fiscal year, there were no material changes in the Trust’s investment objectives or policies that have not been approved by shareholders or in the principal risk factors associated with investment in the Trust. Investment Objective The investment objective of Invesco Municipal Opportunity Trust (the “Trust”) is to provide common shareholders with a high level of current income exempt from federal income tax, consistent with preservation of capital. The investment objective is fundamental and may not be changed without approval of a majority of the Trust’s outstanding voting securities, as defined in the Investment Company Act of 1940, as amended (the “1940 Act”). Investment Policies of the Trust Under normal market conditions, at least 80% of the Trust’s net assets will be invested in municipal securities. The policy stated in the foregoing sentence is a fundamental policy of the Trust and may not be changed without approval of a majority of the Trust’s outstanding voting securities, as defined in the 1940 Act. Under normal market conditions, the Trust’s investment adviser, Invesco Advisers, Inc. (the “Adviser”), seeks to achieve the Trust’s investment objective by investing at least 80% of the Trust’s net assets in investment grade municipal securities. Investment grade securities are: (i) securities rated BBB-or higher by S&P Global Ratings (“S&P”) or Baa3 or higher by Moody’s Investors Service, Inc. (“Moody’s”) or an equivalent rating by another nationally recognized statistical rating organization (“NRSRO”), (ii) securities with comparable short-term NRSRO ratings, or (iii) unrated municipal securities determined by the Adviser to be of comparable quality, each at the time of purchase. Under normal market conditions, the Trust may invest up to 20% of its net assets in municipal securities rated below investment grade or that are unrated but determined by the Adviser to be of comparable quality at the time of purchase. Lower-grade securities are commonly referred to as junk bonds and involve greater risks than investments in higher-grade securities. The Trust may invest in securities that are in default or rated in categories lower than B-by S&P or B3 by Moody’s or unrated securities of comparable quality as part of the foregoing 20% limitation on below investment grade securities. If two or more NRSROs have assigned different ratings to a security, the Adviser uses the highest rating assigned. † The foregoing percentage and rating limitations apply at the time of acquisition of a security based on the last previous determination of the Trust’s net asset value. Any subsequent change in any rating by a rating service or change in percentages resulting from market fluctuations or other changes in the Trust’s total assets will not require elimination of any security from the Trust’s portfolio. The Trust may invest all or a substantial portion of its total assets in municipal securities that may subject certain investors to the federal alternative minimum tax and, therefore, a substantial portion of the income produced by the Trust may be taxable for such investors under the federal alternative minimum tax. Accordingly, the Trust may not be a suitable investment for investors who are already subject to the federal alternative minimum tax or could become subject to the federal alternative minimum tax as a result of an investment in the Trust. The Adviser buys and sells securities for the Trust with a view towards seeking a high level of current income exempt from federal income taxes, subject to reasonable credit risk. As a result, the Trust will not necessarily invest in the highest yielding municipal securities permitted by its investment policies if the Adviser determines that market risks or credit risks associated with such investments would subject the Trust’s portfolio to undue risk. The potential realization of capital gains or losses resulting from possible changes in interest rates will not be a major consideration and frequency of portfolio turnover generally will not be a limiting factor if the Adviser considers it advantageous to purchase or sell securities. The Trust may invest more than 25% of its total assets in a segment of the municipal securities market with similar characteristics if the Adviser determines that the yields available from obligations in a particular segment justify the additional risks of a larger investment in such segment. The Trust may not, however, invest more than 25% of its total assets in municipal securities issued for non-governmental entities that are in the same industry, such as many private activity bonds or industrial development revenue bonds. The Trust has no policy limiting its investments in municipal securities whose issuers are located in the same state. If the Trust were to invest a significant portion of its total assets in issuers located in the same state, it would be more susceptible to adverse economic, business or regulatory conditions in that state. The Adviser actively manages the Trust’s portfolio and adjusts the average maturity of portfolio investments based upon its expectations regarding the direction of interest rates and other economic factors. The Adviser seeks to identify those securities that it believes entail reasonable credit risk considered in relation to the Trust’s investment policies. In selecting securities for investment, the Adviser uses its extensive research capabilities to assess potential investments and considers a number of factors, including general market and economic conditions and interest rate, credit and prepayment risks. Each security considered for investment is subjected to an in-depth credit analysis to evaluate the level of risk it presents. Finally, the Adviser employs leverage in an effort to enhance the Trust’s income and total return. Decisions to purchase or sell securities are determined by the relative value considerations of the portfolio managers that factor in economic and credit-related fundamentals, market supply and demand, market dislocations and situation-specific opportunities. The purchase or sale of securities may be related to a decision to alter the Trust’s macro risk exposure (such as duration, yield curve positioning and sector exposure), a need to limit or reduce the Trust’s exposure to a particular security or issuer, degradation of an issuer’s credit quality, or general liquidity needs of the Trust. The potential for realization of capital gains or losses resulting from possible changes in interest rates will not be a major consideration and frequency of portfolio turnover generally will not be a limiting factor if the Adviser considers it advantageous to purchase or sell securities. Municipal Securities opinion of counsel to the issuer of each such instrument. The yields of municipal securities depend on, among other things, general market conditions, general conditions of the municipal securities market, size of a particular offering, the maturity of the obligation and rating of the issue. There is no limitation as to the maturity of the municipal securities in which the Trust may invest. The ratings of NRSROs represent their opinions of the quality of the municipal securities they undertake to rate. These ratings are general and are not absolute standards of quality. Consequently, municipal securities with the same maturity, coupon and rating may have different yields while municipal securities of the same maturity and coupon with different ratings may have the same yield. The Adviser may adjust the average maturity of the Trust’s portfolio from time to time depending on its assessment of the relative yields available on securities of different maturities and its expectations of future changes in interest rates. The principal types of municipal debt securities purchased by the Trust are revenue obligations and general obligations. Revenue obligations are usually payable only from the revenues derived from a particular facility or class of facilities or, in some cases, from the proceeds of a special excise tax or other specific revenue source, but not from the general taxing power. Revenue obligations may include industrial development, pollution control, public utility, housing, and health care issues. General obligation securities are secured by the issuer’s pledge of its faith, credit and taxing power for the payment of principal and interest. Within these principal classifications of municipal securities, there are a variety of types of municipal securities, including but not limited to: ∎ ∎ ∎ ∎ ∎ ∎ finance the acquisition of equipment and facilities. They may represent participations in a lease, an installment purchase contract or a conditional sales contract. ∎ ∎ ∎ Derivatives Inverse Floating Rate Interests When-Issued and Delayed-Delivery Transactions. Restricted Securities Rule 144A Securities and Other Exempt Securities. Preferred Shares Zero Coupon/Pay-in-Kind Securities. cash income, including zero coupon securities or pay-in-kind securities, when their effective yield over comparable instruments producing cash income makes these investments attractive. Zero coupon securities are debt securities that do not entitle the holder to any periodic payment of interest prior to maturity or a specified date when the securities begin paying current interest. Pay-in-kind securities are debt securities that pay interest through the issuance of additional securities. Temporary Defensive Strategy |
| Risk Factors [Table Text Block] | Principal Risks of Investing in the Trust As with any fund investment, loss of money is a risk of investing. The risks associated with an investment in the Trust can increase during times of significant market volatility. The principal risks of investing in the Trust are: Market Risk Market Disruption Risks Related to Armed Conflict. Ukraine in Europe and Hamas and Israel in the Middle East, has the potential to adversely impact the Fund’s investments. Such conflicts, and other corresponding events, have had, and could continue to have, severe negative effects on regional and global economic and financial markets, including increased volatility, reduced liquidity, and overall uncertainty. The negative impacts may be particularly acute in certain sectors. The timing and duration of such conflicts, resulting sanctions, related events, and other implications cannot be predicted. The foregoing may result in a negative impact on Trust performance and the value of an investment in the Trust, even beyond any direct investment exposure the Trust may have to issuers located in or with significant exposure to an impacted country or geographic regions. Debt Securities Risk Municipal Securities Risk addition, there could be changes in applicable tax laws or tax treatments that reduce or eliminate the current federal income tax exemption on municipal securities or otherwise adversely affect the current federal or state tax status of municipal securities. Changing Fixed Income Market Conditions Risk. Interest Rate Risk Market Discount from Net Asset Value Risk High Yield Debt Securities (Junk Bond/Below-Investment Grade) Risk securities are less liquid than investment grade debt securities and may be difficult to sell at a desirable time or price, particularly in times of negative sentiment toward high yield securities. Medium- and Lower-Grade Municipal Securities Risk Unrated Securities Risk Defaulted Securities Risk speculative and the prices of these securities may be more volatile than non-defaulted securities. Credit Risk Income Risk Call Risk Municipal Issuer Focus Risk Insurance Risk against losses caused by declines in a bond’s value due to a change in market conditions. Alternative Minimum Tax Risk Taxability Risk The value of the Trust’s investments and its net asset value may be adversely affected by changes in tax rates and policies. Because interest income from municipal securities is normally not subject to regular federal income taxation, the attractiveness of municipal securities in relation to other investment alternatives is affected by changes in federal income tax rates or changes in the tax-exempt status of interest income from municipal securities. Any proposed or actual changes in such rates or exempt status, therefore, can significantly affect the demand for and supply, liquidity and marketability of municipal securities. This could in turn affect the Trust’s net asset value and ability to acquire and dispose of municipal securities at desirable yield and price levels. Inverse Floating Rate Interests Risk The Trust, as a holder of the Inverse Floaters, is paid the residual cash flow from the underlying security. Accordingly, the Inverse Floaters provide the Trust with leveraged exposure to the underlying security. The price of Inverse Floaters is expected to decline when interest rates rise, and generally will decline more than the price of a bond with a similar maturity because of the effect of leverage. The price of Inverse Floaters is typically more volatile than the price of bonds with similar maturities especially if the relevant TOB Trust provides the holder of the Inverse Floaters relatively greater leveraged exposure to the underlying security (e.g. if the par amount of the Floaters as a percentage of the par amount of the underlying security is relatively greater). The Trust generally invests in inverse floaters that include embedded leverage, thus exposing the Trust to greater risks and increased costs. The market value of a “leveraged” inverse floater will fluctuate in response to changes in market rates of interest to a greater extent than the value of an unleveraged investment, and the value of, and income earned on, an inverse floater that has a higher degree of leverage are more likely to be eliminated entirely under adverse market conditions. Further, as short-term interest rates rise, the interests payable on the Floaters issued by a TOB Trust also rises, leaving less residual interest cash flow from the underlying security available for payment on the Inverse Floaters. Additionally, Inverse Floaters may lose some or all of their principal and, in some cases, the Trust could lose money in excess of its investment in Inverse Floaters. Consequently, in a rising interest rate environment, the Trust’s investments in Inverse Floaters could negatively impact the Trust’s performance and yield, especially when those Inverse Floaters provide the Trust with relatively greater leveraged exposure to the relevant underlying securities. For additional information regarding the risks of Inverse Floating Rate Obligations, see “Notes to Financial Statements.” Liquidity Risk Restricted Securities Risk Rule 144A Securities and Other Exempt Securities Risk placed, and typically may be resold only to qualified institutional buyers, or in a privately negotiated transaction, or to a limited number of purchasers, or in limited quantities after they have been held for a specified period of time and other conditions are met for an exemption from registration. If there are an insufficient number of qualified institutional buyers interested in purchasing such securities at a particular time, the Trust may have difficulty selling such securities at a desirable time or price. As a result, the Trust’s investment in such securities may be subject to increased liquidity risk. In addition, the issuers of Rule 144A securities may require their qualified institutional buyers (such as the Trust) to keep certain offering information confidential, which could adversely affect the ability of the Trust to sell such securities. Risks of Tobacco Related Bonds Investing in U.S. Territories, Commonwealths and Possessions Risk several years, securities issued by Puerto Rico and its agencies and instrumentalities have been subject to multiple credit downgrades as a result of Puerto Rico’s ongoing fiscal challenges, growing debt obligations and uncertainty about its ability to make full repayment on these obligations, and certain issuers of Puerto Rican municipal securities have filed for bankruptcy and/or failed to make payments on obligations that have come due. Such developments could adversely impact the Trust’s performance and the Trust may pay expenses to preserve its claims related to its Puerto Rican holdings. The outcome of the debt restructuring of certain Puerto Rican issuers in which the Trust invests, both within and outside bankruptcy proceedings is uncertain, and could adversely affect the Trust. Preferred Shares Risk When-Issued, Delayed Delivery and Forward Commitment Risks Zero Coupon or Pay-In-Kind Securities Risk prevents any reinvestment of interest payments at prevailing interest rates if prevailing interest rates rise. The higher yields and interest rates on pay-in-kind securities reflect the payment deferral and increased credit risk associated with such instruments and that such investments may represent a higher credit risk than coupon loans. Pay-in-kind securities may have a potential variability in valuations because their continuing accruals require continuing judgments about the collectability of the deferred payments and the value of any associated collateral. Special tax considerations are associated with investing in certain lower-grade securities, such as zero coupon or pay-in-kind securities. Derivatives Risk Variable-Rate Demand Notes Risk Repurchase Agreement Risk Financial Markets Regulatory Risk plan or other legislation aimed at addressing financial or economic conditions, the threat of a federal government shutdown, and threats not to increase or suspend the federal government’s debt limit, may affect investor and consumer confidence, increase volatility in the financial markets, perhaps suddenly and to a significant degree, result in higher interest rates, and even raise concerns about the U.S. government’s credit rating and ability service its debt. Such changes and events may adversely impact the Trust, including by adversely impacting the Trust’s operations, universe of potential investment options, and return potential. Management Risk |
| Market Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Market Risk |
| Market Disruption Risks Related to Armed Conflict [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Market Disruption Risks Related to Armed Conflict. Ukraine in Europe and Hamas and Israel in the Middle East, has the potential to adversely impact the Fund’s investments. Such conflicts, and other corresponding events, have had, and could continue to have, severe negative effects on regional and global economic and financial markets, including increased volatility, reduced liquidity, and overall uncertainty. The negative impacts may be particularly acute in certain sectors. The timing and duration of such conflicts, resulting sanctions, related events, and other implications cannot be predicted. The foregoing may result in a negative impact on Trust performance and the value of an investment in the Trust, even beyond any direct investment exposure the Trust may have to issuers located in or with significant exposure to an impacted country or geographic regions. |
| Debt Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Debt Securities Risk |
| Municipal Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Municipal Securities Risk addition, there could be changes in applicable tax laws or tax treatments that reduce or eliminate the current federal income tax exemption on municipal securities or otherwise adversely affect the current federal or state tax status of municipal securities. |
| Changing Fixed Income Market Conditions Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Changing Fixed Income Market Conditions Risk. |
| Interests Rate Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Interest Rate Risk |
| Market Discount from Net Asset Value Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Market Discount from Net Asset Value Risk |
| High Yield Debt Securities (Junk BondBelowInvestment Grade) Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | High Yield Debt Securities (Junk Bond/Below-Investment Grade) Risk securities are less liquid than investment grade debt securities and may be difficult to sell at a desirable time or price, particularly in times of negative sentiment toward high yield securities. |
| Medium and LowerGrade Municipal Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Medium- and Lower-Grade Municipal Securities Risk |
| Unrated Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Unrated Securities Risk |
| Defaulted Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Defaulted Securities Risk speculative and the prices of these securities may be more volatile than non-defaulted securities. |
| Credits Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Credit Risk |
| Income Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Income Risk |
| Call Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Call Risk |
| Municipal Issuer Focus Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Municipal Issuer Focus Risk |
| Insurance Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Insurance Risk against losses caused by declines in a bond’s value due to a change in market conditions. |
| Alternative Minimum Tax Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Alternative Minimum Tax Risk |
| Taxability Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Taxability Risk The value of the Trust’s investments and its net asset value may be adversely affected by changes in tax rates and policies. Because interest income from municipal securities is normally not subject to regular federal income taxation, the attractiveness of municipal securities in relation to other investment alternatives is affected by changes in federal income tax rates or changes in the tax-exempt status of interest income from municipal securities. Any proposed or actual changes in such rates or exempt status, therefore, can significantly affect the demand for and supply, liquidity and marketability of municipal securities. This could in turn affect the Trust’s net asset value and ability to acquire and dispose of municipal securities at desirable yield and price levels. |
| Inverse Floating Rate Interests Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Inverse Floating Rate Interests Risk The Trust, as a holder of the Inverse Floaters, is paid the residual cash flow from the underlying security. Accordingly, the Inverse Floaters provide the Trust with leveraged exposure to the underlying security. The price of Inverse Floaters is expected to decline when interest rates rise, and generally will decline more than the price of a bond with a similar maturity because of the effect of leverage. The price of Inverse Floaters is typically more volatile than the price of bonds with similar maturities especially if the relevant TOB Trust provides the holder of the Inverse Floaters relatively greater leveraged exposure to the underlying security (e.g. if the par amount of the Floaters as a percentage of the par amount of the underlying security is relatively greater). The Trust generally invests in inverse floaters that include embedded leverage, thus exposing the Trust to greater risks and increased costs. The market value of a “leveraged” inverse floater will fluctuate in response to changes in market rates of interest to a greater extent than the value of an unleveraged investment, and the value of, and income earned on, an inverse floater that has a higher degree of leverage are more likely to be eliminated entirely under adverse market conditions. Further, as short-term interest rates rise, the interests payable on the Floaters issued by a TOB Trust also rises, leaving less residual interest cash flow from the underlying security available for payment on the Inverse Floaters. Additionally, Inverse Floaters may lose some or all of their principal and, in some cases, the Trust could lose money in excess of its investment in Inverse Floaters. Consequently, in a rising interest rate environment, the Trust’s investments in Inverse Floaters could negatively impact the Trust’s performance and yield, especially when those Inverse Floaters provide the Trust with relatively greater leveraged exposure to the relevant underlying securities. For additional information regarding the risks of Inverse Floating Rate Obligations, see “Notes to Financial Statements.” |
| Liquidity Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Liquidity Risk |
| Restricted Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Restricted Securities Risk |
| Rule 144A Securities and Other Exempt Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Rule 144A Securities and Other Exempt Securities Risk placed, and typically may be resold only to qualified institutional buyers, or in a privately negotiated transaction, or to a limited number of purchasers, or in limited quantities after they have been held for a specified period of time and other conditions are met for an exemption from registration. If there are an insufficient number of qualified institutional buyers interested in purchasing such securities at a particular time, the Trust may have difficulty selling such securities at a desirable time or price. As a result, the Trust’s investment in such securities may be subject to increased liquidity risk. In addition, the issuers of Rule 144A securities may require their qualified institutional buyers (such as the Trust) to keep certain offering information confidential, which could adversely affect the ability of the Trust to sell such securities. |
| Risks of Tobacco Related Bonds [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Risks of Tobacco Related Bonds |
| Investing in U.S. Territories, Commonwealths and Possessions Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Investing in U.S. Territories, Commonwealths and Possessions Risk several years, securities issued by Puerto Rico and its agencies and instrumentalities have been subject to multiple credit downgrades as a result of Puerto Rico’s ongoing fiscal challenges, growing debt obligations and uncertainty about its ability to make full repayment on these obligations, and certain issuers of Puerto Rican municipal securities have filed for bankruptcy and/or failed to make payments on obligations that have come due. Such developments could adversely impact the Trust’s performance and the Trust may pay expenses to preserve its claims related to its Puerto Rican holdings. The outcome of the debt restructuring of certain Puerto Rican issuers in which the Trust invests, both within and outside bankruptcy proceedings is uncertain, and could adversely affect the Trust. |
| Preferred Shares Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Preferred Shares Risk |
| WhenIssued, Delayed Delivery and Forward Commitment Risks [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | When-Issued, Delayed Delivery and Forward Commitment Risks |
| Zero Coupon or PayInKind Securities Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Zero Coupon or Pay-In-Kind Securities Risk prevents any reinvestment of interest payments at prevailing interest rates if prevailing interest rates rise. The higher yields and interest rates on pay-in-kind securities reflect the payment deferral and increased credit risk associated with such instruments and that such investments may represent a higher credit risk than coupon loans. Pay-in-kind securities may have a potential variability in valuations because their continuing accruals require continuing judgments about the collectability of the deferred payments and the value of any associated collateral. Special tax considerations are associated with investing in certain lower-grade securities, such as zero coupon or pay-in-kind securities. |
| Derivatives Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Derivatives Risk |
| VariableRate Demand Notes Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Variable-Rate Demand Notes Risk |
| Repurchase Agreement Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Repurchase Agreement Risk |
| Financial Markets Regulatory Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Financial Markets Regulatory Risk plan or other legislation aimed at addressing financial or economic conditions, the threat of a federal government shutdown, and threats not to increase or suspend the federal government’s debt limit, may affect investor and consumer confidence, increase volatility in the financial markets, perhaps suddenly and to a significant degree, result in higher interest rates, and even raise concerns about the U.S. government’s credit rating and ability service its debt. Such changes and events may adversely impact the Trust, including by adversely impacting the Trust’s operations, universe of potential investment options, and return potential. |
| Management Risk [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | Management Risk |
| Other Risks [Member] | |
| General Description of Registrant [Abstract] | |
| Risk [Text Block] | K. Other Risks Increases in the federal funds and equivalent foreign rates or other changes to monetary policy or regulatory actions may expose fixed income markets to heightened volatility and reduced liquidity for certain fixed income investments, particularly those with longer maturities. It is difficult to predict the impact of interest rate changes on various markets. In addition, decreases in fixed income dealer market-making capacity may also potentially lead to heightened volatility and reduced liquidity in the fixed income markets. As a result, the value of the Trust’s investments and share price may decline. Changes in central bank policies could also result in higher than normal redemptions by shareholders, which could potentially increase the Trust’s portfolio turnover rate and transaction costs. Policy changes by the U.S. government or its regulatory agencies and political events within the U.S. and abroad may, among other things, affect investor and consumer confidence and increase volatility in the financial markets, perhaps suddenly and to a significant degree, which may adversely impact the Trust’s operations, universe of potential investment options, and return potential. |
| Notes [Member] | |
| General Description of Registrant [Abstract] | |
| Investment Objectives and Practices [Text Block] | The Trust’s investment objective is to provide common shareholders with a high level of current income exempt from federal income tax, consistent with preservation of capital. |