| N-2 - USD ($) | 3 Months Ended | 12 Months Ended | ||||||||
| Oct. 31, 2023 | Jul. 31, 2023 | Apr. 30, 2023 | Jan. 31, 2023 | Oct. 31, 2022 | Jul. 31, 2022 | Apr. 30, 2022 | Jan. 31, 2022 | Oct. 31, 2023 | ||
| Cover [Abstract] | ||||||||||
| Entity Central Index Key | 0001562818 | |||||||||
| Amendment Flag | false | |||||||||
| Document Type | N-CSR | |||||||||
| Entity Registrant Name | BlackRock Multi-Sector Income Trust | |||||||||
| Fee Table [Abstract] | ||||||||||
| Shareholder Transaction Expenses [Table Text Block] | Summary of Expenses The following table and example are intended to assist shareholders in understanding the various costs and expenses directly or indirectly associated with investing in BIT’s common shares. BIT Shareholder Transaction Expenses Maximum sales load (as a percentage of offering price) (a) 1.00 % Offering expens es b (a) 0.03 % Dividend reinvestment plan fees $0.02 per share (b) Dividend reinvestment plan sale transaction fee $2.50 (a) If the common shares are sold to or through underwriters, the Prospectus Supplement will set forth any applicable sales load and the estimated offering expenses. Trust shareholders will pay all offering expenses involved with an offering. (b) Computershare Trust Company, N.A. (the “Reinvestment Plan Agent”) fees for the handling of the reinvestment of dividends will be paid by BIT. However, shareholders will pay a $0.02 per share fee incurred in connection with open-market purchases, which will be deducted from the value of the dividend. Shareholders will also be charged a $2.50 sales fee and pay a $0.15 per share fee if a shareholder directs the Reinvestment Plan Agent to sell the common shares held in a dividend reinvestment account. Per share fees include any applicable brokerage commissions the Reinvestment Plan Agent is required to pay. | |||||||||
| Sales Load [Percent] | [1] | 1% | ||||||||
| Dividend Reinvestment and Cash Purchase Fees | [2] | $ 2.5 | ||||||||
| Other Transaction Expenses [Abstract] | ||||||||||
| Other Transaction Expenses [Percent] | [1] | 0.03% | ||||||||
| Annual Expenses [Table Text Block] | E cen e o Investment advisory fees (c)(d) 1.22 % Other expenses 2.70 Miscellaneous 0.10 Interest expense (e) 2.60 Total annual expenses 3.92 Fee waivers (d) — Total annual Trust operating expenses after fee waivers (d) 3.92 (c) BIT currently pays the Manager a monthly fee at an annual contractual investment management fee rate of 0.80% of the average daily value of BIT’s managed assets. For purposes of calculating these fees, “managed assets” means the total assets of BIT (including any assets attributable to money borrowed for investment purposes) minus the sum of BIT’s accrued liabilities (other than money borrowed for investment purposes). (d) BIT and the Manager have entered into a fee waiver agreement (the “Fee Waiver Agreement”), pursuant to which the Manager has contractually agreed to waive the investment advisory fees with respect to any portion of BIT’s assets attributable to investments in any equity and fixed-income mutual funds and exchange-traded funds managed by the Manager or its affiliates that have a contractual management fee, through June 30, 2025. In addition, pursuant to the Fee Waiver Agreement, the Manager has contractually agreed to waive its investment advisory fees by the amount of investment advisory fees BIT pays to the Manager indirectly through its investment in money market funds managed by the Manager or its affiliates, through June 30, 2025. The Fee Waiver Agreement may be terminated at any time, without the payment of any penalty, only by BIT (u (e) Assumes the use of leverage in the form of reverse repurchase agreements representing 35.4% of managed assets at an annual interest expense to BIT of 4.9%, which is based on current market conditions. The actual amount of interest expense borne by BIT will vary over time in accordance with the level of BIT’s use of reverse repurchase agreements and variations in market interest rates. Interest expense is required to be treated as an expense of BIT for accounting purposes. | |||||||||
| Management Fees [Percent] | [3],[4] | 1.22% | ||||||||
| Other Annual Expenses [Abstract] | ||||||||||
| Other Annual Expense 1 [Percent] | 0.10% | |||||||||
| Other Annual Expense 2 [Percent] | [5] | 2.60% | ||||||||
| Other Annual Expenses [Percent] | 2.70% | |||||||||
| Total Annual Expenses [Percent] | 3.92% | |||||||||
| Waivers and Reimbursements of Fees [Percent] | [3] | 0% | ||||||||
| Net Expense over Assets [Percent] | [3] | 3.92% | ||||||||
| Expense Example [Table Text Block] | The following example illustrates BIT’s expenses (including the sales load of $10.00 and offering costs of $0.33) that shareholders would pay on a $1,000 investment in common shares, assuming (i) total net annual expenses of 3.92% of net assets attributable to common shares and (ii) a 5% annual return: 1 Year 3 Years 5 Years 10 Years Total expenses incurred $ 49 $ 129 $ 210 $ 420 The example should not be considered a representation of future expenses. The example assumes that the estimated “Other expenses” set forth in the Estimated Annual Expenses table are accurate and that all dividends and distributions are reinvested at NAV. Actual expenses may be greater or less than those assumed. BIT’s actual rate of return may be greater or less than the hypothetical 5% return shown in the example. | |||||||||
| Expense Example, Year 01 | $ 49 | |||||||||
| Expense Example, Years 1 to 3 | 129 | |||||||||
| Expense Example, Years 1 to 5 | 210 | |||||||||
| Expense Example, Years 1 to 10 | $ 420 | |||||||||
| Purpose of Fee Table , Note [Text Block] | The following table and example are intended to assist shareholders in understanding the various costs and expenses directly or indirectly associated with investing in BIT’s common shares. | |||||||||
| Basis of Transaction Fees, Note [Text Block] | as a percentage of offering price | |||||||||
| Other Transaction Fees, Note [Text Block] | Computershare Trust Company, N.A. (the “Reinvestment Plan Agent”) fees for the handling of the reinvestment of dividends will be paid by BIT. However, shareholders will pay a $0.02 per share fee incurred in connection with open-market purchases, which will be deducted from the value of the dividend. Shareholders will also be charged a $2.50 sales fee and pay a $0.15 per share fee if a shareholder directs the Reinvestment Plan Agent to sell the common shares held in a dividend reinvestment account. Per share fees include any applicable brokerage commissions the Reinvestment Plan Agent is required to pay. | |||||||||
| Management Fee not based on Net Assets, Note [Text Block] | BIT and the Manager have entered into a fee waiver agreement (the “Fee Waiver Agreement”), pursuant to which the Manager has contractually agreed to waive the investment advisory fees with respect to any portion of BIT’s assets attributable to investments in any equity and fixed-income mutual funds and exchange-traded funds managed by the Manager or its affiliates that have a contractual management fee, through June 30, 2025. In addition, pursuant to the Fee Waiver Agreement, the Manager has contractually agreed to waive its investment advisory fees by the amount of investment advisory fees BIT pays to the Manager indirectly through its investment in money market funds managed by the Manager or its affiliates, through June 30, 2025. The Fee Waiver Agreement may be terminated at any time, without the payment of any penalty, only by BIT (u | |||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Investment Objectives and Practices [Text Block] | Investment Objective BlackRock Multi-Sector Income Trust’s (BIT) (the “Trust”) Investment Objectives and Policies The Trust’s primary investment objective is to seek high current income, with a secondary objective of capital appreciation. The Trust’s investment objectives may be changed by the Board of Trustees of the Trust (the “Board,” and each member, a “Trustee”) without prior shareholder approval. In investing the Trust’s assets, BlackRock Advisors, LLC, the Trust’s investment adviser (the “Manager”), and BlackRock International Limited and BlackRock (Singapore) Limited, the Trust’s sub-advisers (each, a “Sub-Advisor” and, collectively with the Manager, the “Managers”), expect to allocate capital across multiple sectors of the fixed-income securities market by evaluating portfolio risk in light of the available investment opportunities and prevailing risks in the fixed-income market, with the goal of delivering attractive risk-adjusted returns. In doing so, the Managers seek to find the appropriate balance between risk mitigation and opportunism. The Managers do not manage the Trust to a benchmark, which provides flexibility to allocate and rotate the Trust’s assets across various sectors within the fixed-income universe. This strategy seeks to provide exposure to those segments of the fixed-income market that the Managers anticipate will provide value while attempting to minimize exposure to those segments that the Managers anticipate will not provide value. If the Managers’ perception of the value of a segment of the fixed-income market or an individual security is incorrect, your investment in the Trust may lose value. Under normal market conditions, the Trust will invest at least 80% of its Managed Assets in loan and debt instruments and other investments with similar economic characteristics (collectively “fixed-income securities”). The Trust may invest directly in securities or synthetically through the use of derivatives. “Managed Assets” means the total assets of the Trust (including any assets attributable to money borrowed for investment purposes) minus the sum of the Trust’s accrued liabilities (other than money borrowed for investment purposes). Fixed-income securities in which the Trust may invest include: • mortgage related securities, including mortgage-backed securities (“MBS”), which are structured debt obligations collateralized by pools of commercial mortgages (commercial mortgage-backed securities or “CMBS”) or residential mortgages (residential mortgage-backed securities or “RMBS”), including agency RMBS issued or guaranteed by U.S. federal agencies or government related guarantors and non-agency RMBS issued by commercial banks, savings and loan institutions, mortgage bankers, private mortgage insurance companies and other non-governmental issuers; collateralized mortgage obligations (“CMOs”); Real Estate Mortgage Investment Conduits (“REMICs”), including resecuritizations of REMICs; stripped mortgage-backed securities, including interest-only (“IO”) and principal-only (“PO”) classes; delegated underwriting and servicing bonds; MBS credit default swaps and other mortgage related derivative instruments; inverse floating rate instruments which are derivative interests in MBS; repurchase agreements supported by MBS; and interests in real estate investment trusts (“REITs”) that invest the majority of their assets in real property mortgages or MBS, including debt and preferred stock issued by mortgage REITs; • asset-backed securities (“ABS”); • U.S. Government and agency securities; • loans and loan participations, including senior secured floating rate and fixed rate loans or debt (“Senior Loans”) and second lien or other subordinated or unsecured floating rate and fixed rate loans or debt (“Second Lien Loans”); • bonds or other debt securities issued by U.S. or foreign (non-U.S.) corporations or other business entities, which may include fixed, variable and floating rate bonds, debentures, notes and other similar types of debt instrument (collectively referred to herein as “corporate bonds”), of any quality, rated or unrated, including those that are rated below investment grade quality; • collateralized loan obligations (“CLOs”); • preferred securities; • convertible securities, including synthetic convertible securities; • sovereign debt, including obligations of foreign governments or their sub-divisions, agencies and government sponsored enterprises and obligations of international agencies and supranational entities; • municipal securities, including taxable municipal securities such as Build America Bonds (“BABs”); and • structured instruments, including structured notes, hybrid or indexed securities, event-linked securities, credit-linked notes (“CLNs”), equity-linked notes and structured credit products. The Trust may invest in fixed-income securities of any type, including those with fixed, floating or variable interest rates, those with interest rates that change based on multiples of changes in a specified reference interest rate or index of interest rates and those with interest rates that change inversely to changes in interest rates, as well as those that do not bear interest. The Trust may hold securities of any duration or maturity and does not maintain set policies with respect to the average duration or maturity of the Trust’s portfolio. Additionally, as part of the Trust’s investments in loans, the Trust may make loans directly to borrowers either as a sole lender or by acting as a member of a syndicate of original lenders. The Trust may invest in securities of any quality, rated or unrated, including those that are rated below investment grade quality (rated Ba/BB or below by Moody’s Investor’s Service, Inc. (“Moody’s”), S&P Global Ratings (“S&P”), or Fitch Ratings, Inc. (“Fitch”)) or securities that are unrated but judged to be of comparable quality by the Managers. Such securities, sometimes referred to as “high yield” or “junk” bonds, are predominantly speculative with respect to the capacity to pay interest and repay principal in accordance with the terms of the security and generally involve greater price volatility than securities in higher rating categories. Under normal market conditions, the Trust will not invest more than 20% of its Managed Assets in securities, other than mortgage related and other asset-backed securities, that are, at the time of investment, rated CCC+ or lower by S&P or Fitch or Caa1 or lower by Moody’s, or that are unrated but judged to be of comparable quality by the Managers. For purposes of applying the foregoing policy, in the case of securities with split ratings (i.e., a security receiving two different ratings from two different rating agencies), the Trust will apply the higher of the applicable ratings. The Trust may invest in mortgage related and other asset backed securities of any quality, rated or unrated, without limitation. Under normal market conditions, the Trust will not invest more than 10% of its Managed Assets in CLOs. Under normal market conditions, the Trust will invest at least 25% of its total assets in mortgage related securities. The Trust’s investment in mortgage related securities may consist entirely of privately issued securities, which are issued by commercial banks, savings and loan institutions, mortgage bankers, private mortgage insurance companies and other non-governmental issuers. The Securities and Exchange Commission (the “SEC”) informed the Trust that it is the view of the SEC staff that privately issued MBS constitute an “industry” for purposes of a fund’s industry concentration policy. On July 8, 2013, the Trust obtained formal “no-action” relief from the staff of the SEC that the staff would not recommend any enforcement action in connection with the Trust’s policy to concentrate its investments in the group of industries constituting mortgage related securities (including privately issued MBS and agency MBS). Under normal market conditions, the Trust may invest up to 20% of its Managed Assets in securities other than fixed-income securities, including common stocks, warrants, depositary receipts and other equity securities. The Trust may invest without limitation in securities of U.S. issuers and non-U.S. issuers located in countries throughout the world, including in developed and emerging markets. Foreign securities in which the Trust may invest may be U.S. dollar-denominated or non-U.S. dollar-denominated. The Trust may invest in securities of issuers of any market capitalization size, including small- and mid-cap companies, and of issuers that operate in any sector or industry. The Trust may also invest in securities of other open- or closed-end investment companies, including exchange-traded funds (“ETFs”), subject to applicable regulatory limits, that invest primarily in securities of the types in which the Trust may invest directly. The Trust treats its investments in open- or closed-end investment companies that invest substantially all of their assets in fixed-income securities as investments in fixed-income securities. The Trust may make short sales of securities. The Trust will not make a short sale if, after giving effect to such sale, the market value of all securities sold short exceeds 25% of the value of its Managed Assets or the Trust’s aggregate short sales of a particular class of securities exceeds 25% of the outstanding securities of that class. During temporary defensive periods, and in order to keep the Trust’s cash fully invested, the Trust may invest up to 100% of its total assets in liquid, short-term investments, including high quality, short-term securities. The Trust may not achieve its investment objectives under these circumstances. The Trust’s investment policies are non-fundamental policies and may be changed by the Board without prior shareholder approval. The Trust’s policy to invest at least 80% of its Managed Assets in fixed-income securities may be changed by the Board; however, if this policy changes, the Trust will provide shareholders at least 60 days’ written notice before implementation of the change. The percentage limitations applicable to the Trust’s portfolio apply only at the time of initial investment and the Trust will not be required to sell investments due to subsequent changes in the value of investments that it owns. Leverage: The Trust may enter into derivative securities transactions that have leverage embedded in them. The Trust may also borrow money as a temporary measure for extraordinary or emergency purposes, including the payment of dividends and the settlement of securities transactions which otherwise might require untimely dispositions of Trust securities. | |||||||||
| Risk Factors [Table Text Block] | 9. PRINCIPAL RISKS In the normal course of business, the Trust invests in securities or other instruments and may enter into certain transactions, and such activities subject the Trust to various risks, including among others, fluctuations in the market (market risk) or failure of an issuer to meet all of its obligations. The value of securities or other instruments may also be affected by various factors, including, without limitation: (i) the general economy; (ii) the overall market as well as local, regional or global political and/or social instability; (iii) regulation, taxation or international tax treaties between various countries; or (iv) currency, interest rate and price fluctuations. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues, recessions, or other events could have a significant impact on the Trust and its investments. Illiquidity Risk: Market Risk: Infectious Illness Risk: Valuation Risk: The price the Trust could receive upon the sale of any particular portfolio investment may differ from the Trust’s valuation of the investment, particularly for securities that trade in thin or volatile markets or that are valued using a fair valuation technique or a price provided by an independent pricing service. Changes to significant unobservable inputs and assumptions (i.e., publicly traded company multiples, growth rate, time to exit) due to the lack of observable inputs may significantly impact the resulting fair value and therefore the Trust’s results of operations. As a result, the price received upon the sale of an investment may be less than the value ascribed by the Trust, and the Trust could realize a greater than expected loss or lesser than expected gain upon the sale of the investment. The Trust’s ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third-party service providers. Counterparty Credit Risk: A derivative contract may suffer a mark-to-market loss if the value of the contract decreases due to an unfavorable change in the market rates or values of the underlying instrument. Losses can also occur if the counterparty does not perform under the contract. With exchange-traded futures and centrally cleared swaps, there is less counterparty credit risk to the Trust since the exchange or clearinghouse, as counterparty to such instruments, guarantees against a possible default. The clearinghouse stands between the buyer and the seller of the contract; therefore, credit risk is limited to failure of the clearinghouse. While offset rights may exist under applicable law, the Trust does not have a contractual right of offset against a clearing broker or clearinghouse in the event of a default (including the bankruptcy or insolvency). Additionally, credit risk exists in exchange-traded futures and centrally cleared swaps with respect to initial and variation margin that is held in a clearing broker’s customer accounts. While clearing brokers are required to segregate customer margin from their own assets, in the event that a clearing broker becomes insolvent or goes into bankruptcy and at that time there is a shortfall in the aggregate amount of margin held by the clearing broker for all its clients, typically the shortfall would be allocated on a pro rata basis across all the clearing broker’s customers, potentially resulting in losses to the Trust. Geographic/Asset Class Risk: The Trust invests a significant portion of its assets in high yield securities. High yield securities that are rated below investment-grade (commonly referred to as “junk bonds”) or are unrated may be deemed speculative, involve greater levels of risk than higher-rated securities of similar maturity and are more likely to default. High yield securities may be issued by less creditworthy issuers, and issuers of high yield securities may be unable to meet their interest or principal payment obligations. High yield securities are subject to extreme price fluctuations, may be less liquid than higher rated fixed-income securities, even under normal economic conditions, and frequently have redemption features. The Trust invests a significant portion of its assets in fixed-income securities and/or uses derivatives tied to the fixed-income markets. Changes in market interest rates or economic conditions may affect the value and/or liquidity of such investments. Interest rate risk is the risk that prices of bonds and other fixed-income securities will decrease as interest rates rise and increase as interest rates fall. The Trust may be subject to a greater risk of rising interest rates due to the period of historically low interest rates that ended in March 2022. The Federal Reserve has recently been raising the federal funds rate as part of its efforts to address inflation. There is a risk that interest rates will continue to rise, which will likely drive down the prices of bonds and other fixed-income securities, and could negatively impact the Trust’s performance. The Trust invests a significant portion of its assets in securities of issuers located in the United States. A decrease in imports or exports, changes in trade regulations, inflation and/or an economic recession in the United States may have a material adverse effect on the U.S. economy and the securities listed on U.S. exchanges. Proposed and adopted policy and legislative changes in the United States may also have a significant effect on U.S. markets generally, as well as on the value of certain securities. Governmental agencies project that the United States will continue to maintain elevated public debt levels for the foreseeable future which may constrain future economic growth. Circumstances could arise that could prevent the timely payment of interest or principal on U.S. government debt, such as reaching the legislative “debt ceiling.” Such non-payment would result in substantial negative consequences for the U.S. economy and the global financial system. If U.S. relations with certain countries deteriorate, it could adversely affect issuers that rely on the United States for trade. The United States has also experienced increased internal unrest and discord. If these trends were to continue, they may have an adverse impact on the U.S. economy and the issuers in which the Trust invests. The Trust invests a significant portion of its assets in securities backed by commercial or residential mortgage loans or in issuers that hold mortgage and other asset-backed securities. When a fund concentrates its investments in this manner, it assumes a greater risk of prepayment or payment extension by securities issuers. Changes in economic conditions, including delinquencies and/or defaults on assets underlying these securities, can affect the value, income and/or liquidity of such positions. Investment percentages in these securities are presented in the Schedule of Investments. LIBOR Transition Risk Risk Factors This section contains a discussion of the general risks of investing in the Trust. The net asset value and market price of, and dividends paid on, the common shares will fluctuate with and be affected by, among other things, the risks more fully described below. As with any fund, there can be no guarantee that the Trust will meet its investment objective or that the Trust’s performance will be positive for any period of time. The order of the below risk factors does not indicate the significance of any particular risk factor. Investment and Market Discount Risk: management investment companies frequently trade at a discount from their net asset value. This risk is separate and distinct from the risk that the Trust’s net asset value could decrease as a result of its investment activities. At any point in time an investment in the Trust’s common shares may be worth less than the original amount invested, even after taking into account distributions paid by the Trust. During periods in which the Trust may use leverage, the Trust’s investment, market discount and certain other risks will be magnified. Concentration Risk: Debt Securities Risk: • Interest Rate Risk — The market value of bonds and other fixed-income securities changes in response to interest rate changes and other factors. Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. The Trust may be subject to a greater risk of rising interest rates due to the recent period of historically low interest rates. For example, if interest rates increase by 1%, assuming a current portfolio duration of ten years, and all other factors being equal, the value of the Trust’s investments would be expected to decrease by 10%. (Duration is a measure of the price sensitivity of a debt security of portfolio of debt securities to relative changes in interest rates.) The magnitude of these fluctuations in the market price of bonds and other fixed-income securities is generally greater for those securities with longer maturities. Fluctuations in the market price of the Trust’s investments will not affect interest income derived from instruments already owned by the Trust, but will be reflected in the Trust’s net asset value. The Trust may lose money if short-term or long-term interest rates rise sharply in a manner not anticipated by Trust management. To the extent the Trust invests in debt securities that may be prepaid at the option of the obligor (such as mortgage-backed securities), the sensitivity of such securities to changes in interest rates may increase (to the detriment of the Trust) when interest rates rise. Moreover, because rates on certain floating rate debt securities typically reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause some fluctuations in the net asset value of the Trust to the extent that it invests in floating rate debt securities. These basic principles of bond prices also apply to U.S. Government securities. A security backed by the “full faith and credit” of the U.S. Government is guaranteed only as to its stated interest rate and face value at maturity, not its current market price. Just like other fixed-income securities, government-guaranteed securities will fluctuate in value when interest rates change. A general rise in interest rates has the potential to cause investors to move out of fixed-income securities on a large scale, which may increase redemptions from funds that hold large amounts of fixed-income securities. Heavy redemptions could cause the Trust to sell assets at inopportune times or at a loss or depressed value and could hurt the Trust’s performance. • Credit Risk — Credit risk refers to the possibility that the issuer of a debt security (i.e., the borrower) will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Trust’s investment in that issuer. The degree of credit risk depends on both the financial condition of the issuer and the terms of the obligation. • Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these obligations to fall. • Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Trust may have to invest the proceeds in securities with lower yields. Mortgage- and Asset-Backed Securities Risks: REIT Investment Risk: U.S. Government Obligations Risk: Senior Loans Risk: of non-payment of scheduled interest or principal or that such collateral could be readily liquidated. To the extent that a senior loan is collateralized by stock in the borrower or its subsidiaries, such stock may lose all of its value in the event of the bankruptcy of the borrower. Uncollateralized senior loans involve a greater risk of loss. Second Lien Loans Risk: CLO Risk: Preferred Securities Risk: Risk of Investing in the United States: Convertible Securities Risk: Sovereign Debt Risk: Municipal Securities Risks: • General Obligation Bonds Risks — Timely payments depend on the issuer’s credit quality, ability to raise tax revenues and ability to maintain an adequate tax base. • Revenue Bonds Risks — These payments depend on the money earned by the particular facility or class of facilities, or the amount of revenues derived from another source. • Private Activity Bonds Risks — Municipalities and other public authorities issue private activity bonds to finance development of industrial facilities for use by a private enterprise. The private enterprise pays the principal and interest on the bond, and the issuer does not pledge its full faith, credit and taxing power for repayment. The Trust’s investments may consist of private activity bonds that may subject certain shareholders to an alternative minimum tax. • Moral Obligation Bonds Risks — Moral obligation bonds are generally issued by special purpose public authorities of a state or municipality. If the issuer is unable to meet its obligations, repayment of these bonds becomes a moral commitment, but not a legal obligation, of the state or municipality. • Municipal Notes Risks — Municipal notes are shorter term municipal debt obligations. If there is a shortfall in the anticipated proceeds, the notes may not be fully repaid and the Trust may lose money. • Municipal Lease Obligations Risks — In a municipal lease obligation, the issuer agrees to make payments when due on the lease obligation. Although the issuer does not pledge its unlimited taxing power for payment of the lease obligation, the lease obligation is secured by the leased property. • Tax-Exempt Status Risk — The Trust and its investment manager will rely on the opinion of issuers’ bond counsel and, in the case of derivative securities, sponsors’ counsel, on the tax-exempt status of interest on municipal bonds and payments under derivative securities. Neither the Trust nor its investment manager will independently review the bases for those tax opinions, which may ultimately be determined to be incorrect and subject the Trust and its shareholders to substantial tax liabilities. Structured Securities Risk: Derivatives Risk: • Leverage Risk — The Trust’s use of derivatives can magnify the Trust’s gains and losses. Relatively small market movements may result in large changes in the value of a derivatives position and can result in losses that greatly exceed the amount originally invested. • Market Risk — Some derivatives are more sensitive to interest rate changes and market price fluctuations than other securities. The Trust could also suffer losses related to its derivatives positions as a result of unanticipated market movements, which losses are potentially unlimited. Finally, the Manager may not be able to predict correctly the direction of securities prices, interest rates and other economic factors, which could cause the Trust’s derivatives positions to lose value. • Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will be unable or unwilling to fulfill its contractual obligation, and the related risks of having concentrated exposure to such a counterparty. • Illiquidity Risk — The possible lack of a liquid secondary market for derivatives and the resulting inability of the Trust to sell or otherwise close a derivatives position could expose the Trust to losses and could make derivatives more difficult for the Trust to value accurately. • Operational Risk — The use of derivatives includes the risk of potential operational issues, including documentation issues, settlement issues, systems failures, inadequate controls and human error. • Legal Risk — The risk of insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract. • Volatility and Correlation Risk — Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. A risk of the Trust’s use of derivatives is that the fluctuations in their values may not correlate with the overall securities markets. • Valuation Risk — Valuation for derivatives may not be readily available in the market. Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. • Hedging Risk — Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that the Trust’s hedging transactions will be effective. The use of hedging may result in certain adverse tax consequences. • Tax Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements and commodity-linked derivative instruments, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority. Such treatment may be less favorable than that given to a direct investment in an underlying asset and may adversely affect the timing, character and amount of income the Trust realizes from its investments. Junk Bonds Risk: Unrated Securities Risk: Equity Securities Risk: Small and Mid-Capitalization Company Risk: Foreign Securities Risk: • The Trust generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. • Changes in foreign currency exchange rates can affect the value of the Trust’s portfolio. • The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. • The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer currency, securities, derivatives or other assets. • Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. • Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. • The Trust’s claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the foreign country, accruals in the Trust’s net asset value for such refunds may be written down partially or in full, which will adversely affect the Trust’s net asset value. Emerging Markets Risk: Investment Companies and ETFs Risk: The securities of other investment companies and ETFs in which the Trust may invest may be leveraged. As a result, the Trust may be indirectly exposed to leverage through an investment in such securities. An investment in securities of other investment companies and ETFs that use leverage may expose the Trust to higher volatility in the market value of such securities and the possibility that the Trust’s long-term returns on such securities (and, indirectly, the long-term returns of shares of the Trust) will be diminished. As with other investments, investments in other investment companies, including ETFs, are subject to market and selection risk. To the extent the Trust is held by an affiliated fund, the ability of the Trust itself to hold other investment companies may be limited. Illiquid Investments Risk: Inverse Floater and Related Securities Risk: Repurchase Agreements and Purchase and Sale Contracts Risk: Short Sales Risk: Leverage Risk: The use of leverage creates an opportunity for increased common share net investment income dividends, but also creates risks for the holders of common shares. The Trust cannot assure you that the use of leverage will result in a higher yield on the common shares. Any leveraging strategy the Trust employs may not be successful. Leverage involves risks and special considerations for common shareholders, including: • the likelihood of greater volatility of net asset value, market price and dividend rate of the common shares than a comparable portfolio without leverage; • the risk that fluctuations in interest rates or dividend rates on any leverage that the Trust must pay will reduce the return to the common shareholders; • the effect of leverage in a declining market, which is likely to cause a greater decline in the net asset value of the common shares than if the Trust were not leveraged, which may result in a greater decline in the market price of the common shares; • leverage may increase operating costs, which may reduce total return. Any decline in the net asset value of the Trust’s investments will be borne entirely by the holders of common shares. Therefore, if the market value of the Trust’s portfolio declines, leverage will result in a greater decrease in net asset value to the holders of common shares than if the Trust were not leveraged. This greater net asset value decrease will also tend to cause a greater decline in the market price for the common shares. Reverse Repurchase Agreements Risk: Dollar Rolls Risk: Market Risk and Selection Risk: An outbreak of an infectious coronavirus (COVID-19) that was first detected in December 2019 developed into a global pandemic that has resulted in numerous disruptions in the market and has had significant economic impact leaving general concern and uncertainty. Although vaccines have been developed and approved for use by various governments, the duration of the pandemic and its effects cannot be predicted with certainty. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general ways that cannot necessarily be foreseen at the present time. | |||||||||
| Share Price [Table Text Block] | The following table summarizes BIT’s highest and lowest daily closing market prices on the NYSE per common share, the NAV per common share, and the premium to or discount from NAV, on the date of each of the high and low market prices. The trading volume indicates the number of common shares traded on the NYSE during the respective quarters. NYSE Market Price NAV per Common Market Price Premium/ on Date of During Quarter Ended High Low High Low High Low Trading Volume October 31, 2023 $ 15.01 $ 13.73 $ 14.51 $ 13.68 3.45 % 0.37 % 5,503,757 July 31, 2023 14.95 14.00 14.55 14.33 2.75 (2.30 ) 5,540,851 April 30, 2023 15.24 14.08 15.29 14.48 (0.33 ) (2.76 ) 6,248,672 January 31, 2023 15.22 14.19 14.73 14.74 3.33 (3.73 ) 6,234,148 October 31, 2022 16.70 14.06 15.70 14.52 6.37 (3.17 ) 6,104,129 July 31, 2022 15.88 13.64 16.15 15.08 (1.67 ) (9.55 ) 7,111,803 April 30, 2022 17.10 15.17 17.27 16.22 (0.98 ) (6.47 ) 7,107,554 January 31, 2022 18.95 16.36 17.97 17.35 5.45 (5.71 ) 7,934,072 As of October 31, 2023, BIT’s market price, NAV per Common Share, and premium/(discount) to NAV per Common Share were $14.09, $13.78, and 2.25%, respectively. | |||||||||
| Share Price | $ 14.09 | $ 14.09 | ||||||||
| NAV Per Share | 13.78 | $ 13.78 | ||||||||
| Latest Premium (Discount) to NAV [Percent] | 2.25% | |||||||||
| Capital Stock, Long-Term Debt, and Other Securities [Abstract] | ||||||||||
| Capital Stock [Table Text Block] | 10. CAPITAL SHARE TRANSACTIONS The Trust is authorized to issue an unlimited number of shares, all of which were initially classified as Common Shares. The Board is authorized, however, to reclassify any unissued Common Shares to Preferred Shares without the approval of Common Shareholders. Common Shares For the periods shown, shares issued and outstanding increased by the following amounts as a result of dividend reinvestment: Year Ended Trust Name 10/31/23 10/31/22 BIT 103,666 74,296 The Trust participates in an open market share repurchase program (the “Repurchase Program”). From December 1, 2021 through November 30, 2022, the Trust may repurchase up to 5% of its outstanding common shares under the Repurchase Program, based on common shares outstanding as of the close of business on November 30, 2021, subject to certain conditions. From December 1, 2022 through November 30, 2023, the Trust may repurchase up to 5% of its outstanding common shares under the Repurchase Program, based on common shares outstanding as of the close of business on November 30, 2022, subject to certain conditions. The Repurchase Program has an accretive effect as shares are purchased at a discount to the Trust’s NAV. There is no assurance that the Trust will purchase shares in any particular amounts. For the year ended October 31, 2023, the Trust did not repurchase any shares. The Trust has filed a prospectus with the SEC allowing it to issue an additional 15,000,000 Common Shares, through an equity Shelf Offering. Under the Shelf Offering, the Trust, subject to market conditions, may raise additional equity capital from time to time in varying amounts and utilizing various offering methods at a net price at or above the Trust’s NAV per Common Share (calculated within 48 hours of pricing). As of period end, 15,000,000 Common Shares remain available for issuance under the Shelf Offering. For the year ended October 31, 2023, Common Shares issued and outstanding under the Shelf Offering remained constant. See Additional Information - Shelf Offering Program for additional information. Initial costs incurred by the Trust in connection with its Shelf Offering are recorded as “Deferred offering costs” in the Statement of Assets and Liabilities. As shares are sold, a portion of the costs attributable to the shares sold will be charged against paid-in-capital. Any remaining deferred charges at the end of the shelf offering period will be charged to expense. | |||||||||
| Outstanding Securities [Table Text Block] | The Trust is authorized to issue an unlimited number of shares, all of which were initially classified as Common Shares. | |||||||||
| Outstanding Security, Held [Shares] | 37,789,586 | |||||||||
| Illiquidity Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Illiquidity Risk: | |||||||||
| Market Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Market Risk: | |||||||||
| Infectious Illness Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Infectious Illness Risk: | |||||||||
| Valuation Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Valuation Risk: The price the Trust could receive upon the sale of any particular portfolio investment may differ from the Trust’s valuation of the investment, particularly for securities that trade in thin or volatile markets or that are valued using a fair valuation technique or a price provided by an independent pricing service. Changes to significant unobservable inputs and assumptions (i.e., publicly traded company multiples, growth rate, time to exit) due to the lack of observable inputs may significantly impact the resulting fair value and therefore the Trust’s results of operations. As a result, the price received upon the sale of an investment may be less than the value ascribed by the Trust, and the Trust could realize a greater than expected loss or lesser than expected gain upon the sale of the investment. The Trust’s ability to value its investments may also be impacted by technological issues and/or errors by pricing services or other third-party service providers. | |||||||||
| Counterparty Credit Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Counterparty Credit Risk: A derivative contract may suffer a mark-to-market loss if the value of the contract decreases due to an unfavorable change in the market rates or values of the underlying instrument. Losses can also occur if the counterparty does not perform under the contract. With exchange-traded futures and centrally cleared swaps, there is less counterparty credit risk to the Trust since the exchange or clearinghouse, as counterparty to such instruments, guarantees against a possible default. The clearinghouse stands between the buyer and the seller of the contract; therefore, credit risk is limited to failure of the clearinghouse. While offset rights may exist under applicable law, the Trust does not have a contractual right of offset against a clearing broker or clearinghouse in the event of a default (including the bankruptcy or insolvency). Additionally, credit risk exists in exchange-traded futures and centrally cleared swaps with respect to initial and variation margin that is held in a clearing broker’s customer accounts. While clearing brokers are required to segregate customer margin from their own assets, in the event that a clearing broker becomes insolvent or goes into bankruptcy and at that time there is a shortfall in the aggregate amount of margin held by the clearing broker for all its clients, typically the shortfall would be allocated on a pro rata basis across all the clearing broker’s customers, potentially resulting in losses to the Trust. | |||||||||
| GeographicAsset Class Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Geographic/Asset Class Risk: The Trust invests a significant portion of its assets in high yield securities. High yield securities that are rated below investment-grade (commonly referred to as “junk bonds”) or are unrated may be deemed speculative, involve greater levels of risk than higher-rated securities of similar maturity and are more likely to default. High yield securities may be issued by less creditworthy issuers, and issuers of high yield securities may be unable to meet their interest or principal payment obligations. High yield securities are subject to extreme price fluctuations, may be less liquid than higher rated fixed-income securities, even under normal economic conditions, and frequently have redemption features. The Trust invests a significant portion of its assets in fixed-income securities and/or uses derivatives tied to the fixed-income markets. Changes in market interest rates or economic conditions may affect the value and/or liquidity of such investments. Interest rate risk is the risk that prices of bonds and other fixed-income securities will decrease as interest rates rise and increase as interest rates fall. The Trust may be subject to a greater risk of rising interest rates due to the period of historically low interest rates that ended in March 2022. The Federal Reserve has recently been raising the federal funds rate as part of its efforts to address inflation. There is a risk that interest rates will continue to rise, which will likely drive down the prices of bonds and other fixed-income securities, and could negatively impact the Trust’s performance. The Trust invests a significant portion of its assets in securities of issuers located in the United States. A decrease in imports or exports, changes in trade regulations, inflation and/or an economic recession in the United States may have a material adverse effect on the U.S. economy and the securities listed on U.S. exchanges. Proposed and adopted policy and legislative changes in the United States may also have a significant effect on U.S. markets generally, as well as on the value of certain securities. Governmental agencies project that the United States will continue to maintain elevated public debt levels for the foreseeable future which may constrain future economic growth. Circumstances could arise that could prevent the timely payment of interest or principal on U.S. government debt, such as reaching the legislative “debt ceiling.” Such non-payment would result in substantial negative consequences for the U.S. economy and the global financial system. If U.S. relations with certain countries deteriorate, it could adversely affect issuers that rely on the United States for trade. The United States has also experienced increased internal unrest and discord. If these trends were to continue, they may have an adverse impact on the U.S. economy and the issuers in which the Trust invests. The Trust invests a significant portion of its assets in securities backed by commercial or residential mortgage loans or in issuers that hold mortgage and other asset-backed securities. When a fund concentrates its investments in this manner, it assumes a greater risk of prepayment or payment extension by securities issuers. Changes in economic conditions, including delinquencies and/or defaults on assets underlying these securities, can affect the value, income and/or liquidity of such positions. Investment percentages in these securities are presented in the Schedule of Investments. | |||||||||
| LIBOR Transition Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | LIBOR Transition Risk | |||||||||
| Investment and Market Discount Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Investment and Market Discount Risk: management investment companies frequently trade at a discount from their net asset value. This risk is separate and distinct from the risk that the Trust’s net asset value could decrease as a result of its investment activities. At any point in time an investment in the Trust’s common shares may be worth less than the original amount invested, even after taking into account distributions paid by the Trust. During periods in which the Trust may use leverage, the Trust’s investment, market discount and certain other risks will be magnified. | |||||||||
| Concentration Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Concentration Risk: | |||||||||
| Debt Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Debt Securities Risk: • Interest Rate Risk — The market value of bonds and other fixed-income securities changes in response to interest rate changes and other factors. Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise. The Trust may be subject to a greater risk of rising interest rates due to the recent period of historically low interest rates. For example, if interest rates increase by 1%, assuming a current portfolio duration of ten years, and all other factors being equal, the value of the Trust’s investments would be expected to decrease by 10%. (Duration is a measure of the price sensitivity of a debt security of portfolio of debt securities to relative changes in interest rates.) The magnitude of these fluctuations in the market price of bonds and other fixed-income securities is generally greater for those securities with longer maturities. Fluctuations in the market price of the Trust’s investments will not affect interest income derived from instruments already owned by the Trust, but will be reflected in the Trust’s net asset value. The Trust may lose money if short-term or long-term interest rates rise sharply in a manner not anticipated by Trust management. To the extent the Trust invests in debt securities that may be prepaid at the option of the obligor (such as mortgage-backed securities), the sensitivity of such securities to changes in interest rates may increase (to the detriment of the Trust) when interest rates rise. Moreover, because rates on certain floating rate debt securities typically reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause some fluctuations in the net asset value of the Trust to the extent that it invests in floating rate debt securities. These basic principles of bond prices also apply to U.S. Government securities. A security backed by the “full faith and credit” of the U.S. Government is guaranteed only as to its stated interest rate and face value at maturity, not its current market price. Just like other fixed-income securities, government-guaranteed securities will fluctuate in value when interest rates change. A general rise in interest rates has the potential to cause investors to move out of fixed-income securities on a large scale, which may increase redemptions from funds that hold large amounts of fixed-income securities. Heavy redemptions could cause the Trust to sell assets at inopportune times or at a loss or depressed value and could hurt the Trust’s performance. • Credit Risk — Credit risk refers to the possibility that the issuer of a debt security (i.e., the borrower) will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Trust’s investment in that issuer. The degree of credit risk depends on both the financial condition of the issuer and the terms of the obligation. • Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these obligations to fall. • Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Trust may have to invest the proceeds in securities with lower yields. | |||||||||
| Mortgage and AssetBacked Securities Risks [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Mortgage- and Asset-Backed Securities Risks: | |||||||||
| REIT Investment Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | REIT Investment Risk: | |||||||||
| U.S. Government Obligations Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | U.S. Government Obligations Risk: | |||||||||
| Senior Loans Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Senior Loans Risk: of non-payment of scheduled interest or principal or that such collateral could be readily liquidated. To the extent that a senior loan is collateralized by stock in the borrower or its subsidiaries, such stock may lose all of its value in the event of the bankruptcy of the borrower. Uncollateralized senior loans involve a greater risk of loss. | |||||||||
| Second Lien Loans Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Second Lien Loans Risk: | |||||||||
| CLO Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | CLO Risk: | |||||||||
| Preferred Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Preferred Securities Risk: | |||||||||
| Risk of Investing in the United States [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Risk of Investing in the United States: | |||||||||
| Convertible Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Convertible Securities Risk: | |||||||||
| Sovereign Debt Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Sovereign Debt Risk: | |||||||||
| Municipal Securities Risks [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Municipal Securities Risks: • General Obligation Bonds Risks — Timely payments depend on the issuer’s credit quality, ability to raise tax revenues and ability to maintain an adequate tax base. • Revenue Bonds Risks — These payments depend on the money earned by the particular facility or class of facilities, or the amount of revenues derived from another source. • Private Activity Bonds Risks — Municipalities and other public authorities issue private activity bonds to finance development of industrial facilities for use by a private enterprise. The private enterprise pays the principal and interest on the bond, and the issuer does not pledge its full faith, credit and taxing power for repayment. The Trust’s investments may consist of private activity bonds that may subject certain shareholders to an alternative minimum tax. • Moral Obligation Bonds Risks — Moral obligation bonds are generally issued by special purpose public authorities of a state or municipality. If the issuer is unable to meet its obligations, repayment of these bonds becomes a moral commitment, but not a legal obligation, of the state or municipality. • Municipal Notes Risks — Municipal notes are shorter term municipal debt obligations. If there is a shortfall in the anticipated proceeds, the notes may not be fully repaid and the Trust may lose money. • Municipal Lease Obligations Risks — In a municipal lease obligation, the issuer agrees to make payments when due on the lease obligation. Although the issuer does not pledge its unlimited taxing power for payment of the lease obligation, the lease obligation is secured by the leased property. • Tax-Exempt Status Risk — The Trust and its investment manager will rely on the opinion of issuers’ bond counsel and, in the case of derivative securities, sponsors’ counsel, on the tax-exempt status of interest on municipal bonds and payments under derivative securities. Neither the Trust nor its investment manager will independently review the bases for those tax opinions, which may ultimately be determined to be incorrect and subject the Trust and its shareholders to substantial tax liabilities. | |||||||||
| Structured Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Structured Securities Risk: | |||||||||
| Derivatives Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Derivatives Risk: • Leverage Risk — The Trust’s use of derivatives can magnify the Trust’s gains and losses. Relatively small market movements may result in large changes in the value of a derivatives position and can result in losses that greatly exceed the amount originally invested. • Market Risk — Some derivatives are more sensitive to interest rate changes and market price fluctuations than other securities. The Trust could also suffer losses related to its derivatives positions as a result of unanticipated market movements, which losses are potentially unlimited. Finally, the Manager may not be able to predict correctly the direction of securities prices, interest rates and other economic factors, which could cause the Trust’s derivatives positions to lose value. • Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will be unable or unwilling to fulfill its contractual obligation, and the related risks of having concentrated exposure to such a counterparty. • Illiquidity Risk — The possible lack of a liquid secondary market for derivatives and the resulting inability of the Trust to sell or otherwise close a derivatives position could expose the Trust to losses and could make derivatives more difficult for the Trust to value accurately. • Operational Risk — The use of derivatives includes the risk of potential operational issues, including documentation issues, settlement issues, systems failures, inadequate controls and human error. • Legal Risk — The risk of insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract. • Volatility and Correlation Risk — Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. A risk of the Trust’s use of derivatives is that the fluctuations in their values may not correlate with the overall securities markets. • Valuation Risk — Valuation for derivatives may not be readily available in the market. Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them. • Hedging Risk — Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that the Trust’s hedging transactions will be effective. The use of hedging may result in certain adverse tax consequences. • Tax Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements and commodity-linked derivative instruments, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority. Such treatment may be less favorable than that given to a direct investment in an underlying asset and may adversely affect the timing, character and amount of income the Trust realizes from its investments. | |||||||||
| Junk Bonds Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Junk Bonds Risk: | |||||||||
| Unrated Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Unrated Securities Risk: | |||||||||
| Equity Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Equity Securities Risk: | |||||||||
| Small and MidCapitalization Company Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Small and Mid-Capitalization Company Risk: | |||||||||
| Foreign Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Foreign Securities Risk: • The Trust generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight. • Changes in foreign currency exchange rates can affect the value of the Trust’s portfolio. • The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position. • The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer currency, securities, derivatives or other assets. • Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws. • Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments. • The Trust’s claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the foreign country, accruals in the Trust’s net asset value for such refunds may be written down partially or in full, which will adversely affect the Trust’s net asset value. | |||||||||
| Emerging Markets Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Emerging Markets Risk: | |||||||||
| Investment Companies and ETFs Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Investment Companies and ETFs Risk: The securities of other investment companies and ETFs in which the Trust may invest may be leveraged. As a result, the Trust may be indirectly exposed to leverage through an investment in such securities. An investment in securities of other investment companies and ETFs that use leverage may expose the Trust to higher volatility in the market value of such securities and the possibility that the Trust’s long-term returns on such securities (and, indirectly, the long-term returns of shares of the Trust) will be diminished. As with other investments, investments in other investment companies, including ETFs, are subject to market and selection risk. To the extent the Trust is held by an affiliated fund, the ability of the Trust itself to hold other investment companies may be limited. | |||||||||
| Illiquid Investments Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Illiquid Investments Risk: | |||||||||
| Inverse Floater and Related Securities Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Inverse Floater and Related Securities Risk: | |||||||||
| Repurchase Agreements and Purchase and Sale Contracts Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Repurchase Agreements and Purchase and Sale Contracts Risk: | |||||||||
| Short Sales Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Short Sales Risk: | |||||||||
| Leverage Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Leverage Risk: The use of leverage creates an opportunity for increased common share net investment income dividends, but also creates risks for the holders of common shares. The Trust cannot assure you that the use of leverage will result in a higher yield on the common shares. Any leveraging strategy the Trust employs may not be successful. Leverage involves risks and special considerations for common shareholders, including: • the likelihood of greater volatility of net asset value, market price and dividend rate of the common shares than a comparable portfolio without leverage; • the risk that fluctuations in interest rates or dividend rates on any leverage that the Trust must pay will reduce the return to the common shareholders; • the effect of leverage in a declining market, which is likely to cause a greater decline in the net asset value of the common shares than if the Trust were not leveraged, which may result in a greater decline in the market price of the common shares; • leverage may increase operating costs, which may reduce total return. Any decline in the net asset value of the Trust’s investments will be borne entirely by the holders of common shares. Therefore, if the market value of the Trust’s portfolio declines, leverage will result in a greater decrease in net asset value to the holders of common shares than if the Trust were not leveraged. This greater net asset value decrease will also tend to cause a greater decline in the market price for the common shares. | |||||||||
| Reverse Repurchase Agreements Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Reverse Repurchase Agreements Risk: | |||||||||
| Dollar Rolls Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Dollar Rolls Risk: | |||||||||
| Market Risk and Selection Risk [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Risk [Text Block] | Market Risk and Selection Risk: An outbreak of an infectious coronavirus (COVID-19) that was first detected in December 2019 developed into a global pandemic that has resulted in numerous disruptions in the market and has had significant economic impact leaving general concern and uncertainty. Although vaccines have been developed and approved for use by various governments, the duration of the pandemic and its effects cannot be predicted with certainty. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general ways that cannot necessarily be foreseen at the present time. | |||||||||
| Common Shares [Member] | ||||||||||
| General Description of Registrant [Abstract] | ||||||||||
| Lowest Price or Bid | 13.73 | $ 14 | $ 14.08 | $ 14.19 | $ 14.06 | $ 13.64 | $ 15.17 | $ 16.36 | ||
| Highest Price or Bid | 15.01 | 14.95 | 15.24 | 15.22 | 16.7 | 15.88 | 17.1 | 18.95 | ||
| Lowest Price or Bid, NAV | 13.68 | 14.33 | 14.48 | 14.74 | 14.52 | 15.08 | 16.22 | 17.35 | ||
| Highest Price or Bid, NAV | $ 14.51 | $ 14.55 | $ 15.29 | $ 14.73 | $ 15.7 | $ 16.15 | $ 17.27 | $ 17.97 | ||
| Highest Price or Bid, Premium (Discount) to NAV [Percent] | 3.45% | 2.75% | (0.33%) | 3.33% | 6.37% | (1.67%) | (0.98%) | 5.45% | ||
| Lowest Price or Bid, Premium (Discount) to NAV [Percent] | 0.37% | (2.30%) | (2.76%) | (3.73%) | (3.17%) | (9.55%) | (6.47%) | (5.71%) | ||
| [1]If the common shares are sold to or through underwriters, the Prospectus Supplement will set forth any applicable sales load and the estimated offering expenses. Trust shareholders will pay all offering expenses involved with an offering.[2]Computershare Trust Company, N.A. (the “Reinvestment Plan Agent”) fees for the handling of the reinvestment of dividends will be paid by BIT. However, shareholders will pay a $0.02 per share fee incurred in connection with open-market purchases, which will be deducted from the value of the dividend. Shareholders will also be charged a $2.50 sales fee and pay a $0.15 per share fee if a shareholder directs the Reinvestment Plan Agent to sell the common shares held in a dividend reinvestment account. Per share fees include any applicable brokerage commissions the Reinvestment Plan Agent is required to pay.[3]BIT and the Manager have entered into a fee waiver agreement (the “Fee Waiver Agreement”), pursuant to which the Manager has contractually agreed to waive the investment advisory fees with respect to any portion of BIT’s assets attributable to investments in any equity and fixed-income mutual funds and exchange-traded funds managed by the Manager or its affiliates that have a contractual management fee, through June 30, 2025. In addition, pursuant to the Fee Waiver Agreement, the Manager has contractually agreed to waive its investment advisory fees by the amount of investment advisory fees BIT pays to the Manager indirectly through its investment in money market funds managed by the Manager or its affiliates, through June 30, 2025. The Fee Waiver Agreement may be terminated at any time, without the payment of any penalty, only by BIT (upon the vote of a majority of the Trustees who are not “interested persons” (as defined in the Investment Company Act of 1940, as amended (the “Investment Company Act”), of BIT (the “Independent Trustees”)) or a majority of the outstanding voting securities of BIT), upon 90 days’ written notice by BIT to the Manager.[4]BIT currently pays the Manager a monthly fee at an annual contractual investment management fee rate of 0.80% of the average daily value of BIT’s managed assets. For purposes of calculating these fees, “managed assets” means the total assets of BIT (including any assets attributable to money borrowed for investment purposes) minus the sum of BIT’s accrued liabilities (other than money borrowed for investment purposes).[5]Assumes the use of leverage in the form of reverse repurchase agreements representing 35.4% of managed assets at an annual interest expense to BIT of 4.9%, which is based on current market conditions. The actual amount of interest expense borne by BIT will vary over time in accordance with the level of BIT’s use of reverse repurchase agreements and variations in market interest rates. Interest expense is required to be treated as an expense of BIT for accounting purposes. | ||||||||||
