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    <unit id="pure">
        <measure>pure</measure>
    </unit>
    <unit id="Years">
        <measure>utr:Y</measure>
    </unit>
    <dei:EntityInvCompanyType contextRef="Context_20250531_20250531" id="ixv-34763">N-1A</dei:EntityInvCompanyType>
    <dei:EntityRegistrantName contextRef="Context_20250531_20250531" id="ixv-34764">BNY Mellon Intermediate Municipal Bond Fund, Inc.</dei:EntityRegistrantName>
    <dei:DocumentEffectiveDate contextRef="Context_20250531_20250531" id="ixv-34765">2025-09-30</dei:DocumentEffectiveDate>
    <oef:ProspectusDate contextRef="Context_20250531_20250531" id="ixv-34766">2025-09-30</oef:ProspectusDate>
    <oef:RiskReturnHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34767">Fund 
Summary</oef:RiskReturnHeading>
    <oef:ObjectiveHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34768"> Investment 
Objective</oef:ObjectiveHeading>
    <oef:ObjectivePrimaryTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34769">The fund seeks the maximum amount of current 
income exempt from federal income tax as is consistent with the preservation of capital.</oef:ObjectivePrimaryTextBlock>
    <oef:ExpenseHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34770">Fees 
and Expenses</oef:ExpenseHeading>
    <oef:ExpenseNarrativeTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-247">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; font-weight:normal; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;This table describes the fees and expenses 
that you may pay if you buy, hold and sell shares of the fund.  &lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:bold; text-decoration:none;"&gt;You may 
pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not 
reflected in the table and examples below.&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;  &lt;/span&gt;&lt;/p&gt;</oef:ExpenseNarrativeTextBlock>
    <oef:OperatingExpensesCaption
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34771">Annual 
Fund Operating Expenses (expenses that you pay each year as a percentage of the value 
of your investment)</oef:OperatingExpensesCaption>
    <oef:ManagementFeesOverAssets
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34772"
      unitRef="pure">0.0045</oef:ManagementFeesOverAssets>
    <oef:Component2OtherExpensesOverAssets
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34773"
      unitRef="pure">0.0007</oef:Component2OtherExpensesOverAssets>
    <oef:Component3OtherExpensesOverAssets
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34774"
      unitRef="pure">0.0011</oef:Component3OtherExpensesOverAssets>
    <oef:OtherExpensesOverAssets
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34775"
      unitRef="pure">0.0018</oef:OtherExpensesOverAssets>
    <oef:ExpensesOverAssets
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34776"
      unitRef="pure">0.0063</oef:ExpensesOverAssets>
    <oef:ExpenseExampleHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34777">Example</oef:ExpenseExampleHeading>
    <oef:ExpenseExampleNarrativeTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-295">&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;The Example is intended to help you compare the cost of investing in the fund 
with the cost of investing in other mutual funds.  The Example assumes that you invest $10,000 in the 
fund for the time periods indicated and then hold or redeem all of your shares at the end of those periods. 
 The Example also assumes that your investment has a 5% return each year and that the fund's operating 
expenses remain the same.  Although your actual costs may be higher or lower, based on these assumptions 
your costs would be:&lt;/p&gt;</oef:ExpenseExampleNarrativeTextBlock>
    <oef:ExpenseExampleYear01
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34778"
      unitRef="usd">64</oef:ExpenseExampleYear01>
    <oef:ExpenseExampleYear03
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34779"
      unitRef="usd">202</oef:ExpenseExampleYear03>
    <oef:ExpenseExampleYear05
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34780"
      unitRef="usd">351</oef:ExpenseExampleYear05>
    <oef:ExpenseExampleYear10
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34781"
      unitRef="usd">786</oef:ExpenseExampleYear10>
    <oef:PortfolioTurnoverHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34782">Portfolio 
Turnover</oef:PortfolioTurnoverHeading>
    <oef:PortfolioTurnoverTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-322">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;The fund pays transaction costs, such as commissions, 
when it buys and sells securities (or "turns over" its portfolio).  A higher portfolio turnover may indicate 
higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. 
 These costs, which are not reflected in annual fund operating expenses or in the Example, affect the 
fund's performance.  During the most recent fiscal year, the fund's portfolio turnover rate was 25.19% 
of the average value of its portfolio.&lt;/p&gt;</oef:PortfolioTurnoverTextBlock>
    <oef:PortfolioTurnoverRate
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34783"
      unitRef="pure">0.2519</oef:PortfolioTurnoverRate>
    <oef:StrategyHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34784">Principal 
Investment Strategy</oef:StrategyHeading>
    <oef:StrategyNarrativeTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-327">&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;To pursue its goal, the fund 
normally invests at least 80% of its net assets, plus any borrowings for investment purposes, in municipal 
bonds that provide income exempt from federal personal income tax.  Typically, the fund invests substantially 
all of its assets in such municipal bonds.  Municipal bonds are debt securities or other obligations 
issued by states, territories and possessions of the United States and the District of Columbia and their 
political subdivisions, agencies and instrumentalities, or multistate agencies and authorities. &lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;The fund invests at least 80% of its net assets in municipal bonds rated, at the 
time of purchase, A or higher or the unrated equivalent as determined by Insight North America LLC, the 
fund's sub-adviser.  The fund may invest up to 20% of its net assets in municipal bonds rated, at the 
time of purchase, below A, including bonds rated below investment grade ("high yield" or "junk" bonds) 
or the unrated equivalent as determined by the fund's sub-adviser.  The dollar-weighted average maturity 
of the fund's portfolio generally is between three and ten years.  A bond's maturity is &lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;the length of time until the principal must be fully repaid with interest.  Dollar-weighted 
average maturity is an average of the stated maturities of the bonds held by the fund, based on their 
dollar-weighted proportions in the fund.&lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;The fund's sub-adviser focuses 
on identifying undervalued sectors and securities.  To select municipal bonds for the fund, the sub-adviser 
uses fundamental credit analysis to estimate the relative value and attractiveness of various sectors 
and securities and actively trades among various sectors and securities based on their apparent relative 
values.  The fund seeks to invest in several different sectors, and does not seek to overweight any particular 
sector but may do so depending on each sector's relative value at a given time.&lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;A 
rigorous sell discipline is employed to continuously evaluate all fund holdings.  Current holdings may 
become sell candidates if creditworthiness is deteriorating, if bonds with better risk and return characteristics 
become available, or if the holding no longer meets the sub-adviser's strategic or portfolio construction 
objectives.&lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;Although the fund seeks to provide income exempt from federal 
income tax, income from some of the fund's holdings may be subject to the federal alternative minimum 
tax.&lt;/p&gt;</oef:StrategyNarrativeTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_PrincipalRisks2_S000000073Summary1Member"
      id="ixv-338">&lt;div style="border-bottom:0.25pt; border-bottom-style:solid; border-bottom-color:#000000; padding:0pt 0pt 1pt 0pt;"&gt;&lt;div style="font-size:12.0pt; font-family:Arial; text-align:left; color:#000000; font-weight:bold;"&gt;&lt;span style="font-size:12.0pt; font-family:Arial; font-style:normal; color:#000000; font-weight:bold; text-decoration:none;"&gt;Principal 
Risks&lt;/span&gt;&lt;/div&gt;&lt;/div&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;An investment in the fund is not a bank deposit. 
 It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government 
agency.  It is not a complete investment program.  The fund's share price fluctuates, sometimes dramatically, 
which means you could lose money.&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_RiskNotInsuredMember_S000000073Summary1Member"
      id="ixv-34785">An investment in the fund is not a bank deposit. 
 It is not insured or guaranteed by the Federal Deposit Insurance Corporation (FDIC) or any other government 
agency.</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_RiskLoseMoneyMember_S000000073Summary1Member"
      id="ixv-34786">  The fund's share price fluctuates, sometimes dramatically, 
which means you could lose money.</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Municipalsecuritiesrisk2_S000000073Summary1Member"
      id="ixv-343">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Municipal securities risk:&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;  Municipal 
securities are subject to interest rate, credit, liquidity, valuation, market and political risks.  The 
amount of public information available about municipal securities is generally less than that for corporate 
equities or bonds.  Special factors, such as legislative and regulatory changes, executive orders, voter 
initiatives, and state and local economic and business developments, may adversely affect the value of 
the fund's investments in municipal securities.  Other factors include the general conditions of the 
municipal securities market, the size of the particular offering, the maturity of the obligation and 
the rating of the issue.  Changes in economic, business or political conditions, or public health developments, 
relating to a particular municipal project, municipality, or state, territory or possession of the United 
States in which the fund invests may have an impact on the fund's share price.  Any credit impairment 
could adversely impact the value of municipal bonds, which could negatively impact the performance of 
the fund.  In addition, income from municipal securities held by the fund could be declared taxable because 
of, among other things, unfavorable changes in tax laws, adverse interpretations by the Internal Revenue 
Service or state tax authorities, or noncompliant conduct of an issuer or other obligated party.  Loss 
of tax-exempt status for municipal securities held by the fund may cause interest received and distributed 
to shareholders by the fund to be taxable and may result in a significant decline in the values of such 
municipal securities.  &lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Interestraterisk2_S000000073Summary1Member"
      id="ixv-349">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Interest rate risk:  &lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;Prices 
of bonds and other fixed rate fixed-income securities tend to move inversely with changes in interest 
rates.  Typically, a rise in rates will adversely affect fixed-income securities and, accordingly, will 
cause the value of the fund's investments in these securities to decline.  A wide variety of market factors 
can cause interest rates to rise, including central bank monetary policy, rising inflation and changes 
in general economic conditions.  It is difficult to predict the pace at which central banks or monetary 
authorities may increase (or decrease) interest rates or the timing, frequency, or magnitude of such 
changes.  During periods of very low interest rates, which occur from time to time due to market forces 
or actions of governments and/or their central banks, including the Board of Governors of the Federal 
Reserve System in the U.S., the fund may be subject to a greater risk of principal decline from rising 
interest rates.  When interest rates fall, the fund's investments in new securities may be at lower yields 
and may reduce the fund's income.  Changing interest rates may have unpredictable effects on markets, 
may result in heightened market volatility and may detract from fund performance.  The magnitude of these 
fluctuations in the market price of fixed-income securities is generally greater for securities with 
longer effective maturities and durations because such instruments do not mature, reset interest rates 
or become callable for longer periods of time.  Unlike investment grade bonds, however, the prices of 
high yield ("junk") bonds may fluctuate unpredictably and not necessarily inversely with changes in interest 
rates.    &lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Creditrisk2_S000000073Summary1Member"
      id="ixv-355">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Credit 
risk&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;:  Failure of an issuer of a security to make timely interest or principal payments 
when due, or a decline or perception of a decline in the credit quality of the security, can cause the 
security's price to fall.  The lower a security's credit rating, the greater the chance that the issuer 
of the security will default or fail to meet its payment obligations.&lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Highyieldsecuritiesrisk2_S000000073Summary1Member"
      id="ixv-361">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;High 
yield securities risk&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;:  High yield ("junk") securities involve greater credit risk, 
including the risk of default, than investment grade securities, and are considered predominantly speculative 
with respect to the issuer's ability to make principal and interest payments.  These securities are especially 
sensitive to adverse changes in general economic conditions, to changes in the financial condition of 
their issuers and to price fluctuation in response to changes in interest rates.  During periods of economic 
downturn or rising interest rates, issuers of below investment grade &lt;/span&gt;&lt;/p&gt;&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; margin-left:8.65pt; text-decoration:none;"&gt;securities may experience financial stress that could adversely 
affect their ability to make payments of principal and interest and increase the possibility of default.&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Liquidityrisk2_S000000073Summary1Member"
      id="ixv-372">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Liquidity 
risk&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;:  &lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;When there is little or no active trading market 
for specific types of securities, it can become more difficult to sell the securities in a timely manner 
at or near their perceived value.  In such a market, the value of such securities and the fund's share 
price may fall dramatically.  The secondary market for certain municipal bonds tends to be less well 
developed or liquid than many other securities markets, which may adversely affect the fund's ability 
to buy or sell such municipal bonds at attractive prices.  Investments that are illiquid or that trade 
in lower volumes may be more difficult to value.  The market for below investment grade securities may 
be less liquid and therefore these securities may be harder to value or sell at an acceptable price, 
especially during times of market volatility or decline.&lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Valuationrisk2_S000000073Summary1Member"
      id="ixv-379">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Valuation risk:&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;  The 
price that the fund could receive upon the sale (or other disposition) of an investment may differ from 
the fund's valuation of the investment, particularly for investments that trade in lower volumes, investments 
that are valued using a fair valuation methodology or a price provided by an independent pricing service, 
or during market turmoil or volatility.  As a result, the price received upon the sale of an investment 
may be less than the value ascribed by the fund, and the fund could realize a greater than expected loss 
or lesser than expected gain upon the sale of the investment.  &lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Marketrisk2_S000000073Summary1Member"
      id="ixv-385">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Market 
risk:  &lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;The value of the securities in which the fund invests may be affected by political, 
regulatory, economic and social developments, and developments that impact specific economic sectors, 
industries or segments of the market.&#160; In addition, turbulence in financial markets and reduced liquidity 
in equity, credit and/or fixed-income markets may negatively affect many issuers, which could adversely 
affect the fund.&#160; Global economies and financial markets are becoming increasingly interconnected, and 
conditions and events in one country, region or financial market may adversely impact issuers in a different 
country, region or financial market.&#160; These risks may be magnified if certain events or developments 
adversely interrupt the global supply chain; in these and other circumstances, such risks might affect 
companies world-wide.  Local, regional or global events such as war, military conflicts, acts of terrorism, 
natural disasters, the spread of infectious illness or other public health issues, recessions, elevated 
levels of government debt, changes in trade regulation or economic sanctions, internal unrest and discord, 
or other events could have a significant impact on the fund and its investments.&lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:RiskTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_Managementrisk2_S000000073Summary1Member"
      id="ixv-391">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-8.65pt; font-weight:normal; margin-left:8.65pt; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Symbol; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;&#xb7;&lt;/span&gt;&lt;span style="word-spacing:5.325pt;"&gt;&#160;&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; color:#000000; font-weight:normal; text-decoration:none;"&gt;Management 
risk:  &lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; color:#000000; font-weight:normal; text-decoration:none;"&gt;The investment process used by the fund's sub-adviser could fail to achieve the 
fund's investment goal and cause your fund investment to lose value.  &lt;/span&gt;&lt;/p&gt;</oef:RiskTextBlock>
    <oef:BarChartAndPerformanceTableHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34787">Performance</oef:BarChartAndPerformanceTableHeading>
    <oef:PerformanceNarrativeTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-400">&lt;p style="-sec-ix-redline:true;font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;The following bar chart and table provide some indication of the risks of investing 
in the fund.  The bar chart shows changes in the performance of the fund's shares from year to year. 
 The table compares the average annual total returns of the fund's shares to those of the Bloomberg U.S. 
Municipal Bond Index, a broad measure of market performance, and the Bloomberg Municipal Bond: 7 Year 
Index (6-8).  The fund's past performance (before and after taxes) is not necessarily an indication of 
how the fund will perform in the future.  More recent performance information may be available at www.by.com/investments.&lt;/p&gt;</oef:PerformanceNarrativeTextBlock>
    <oef:PerformancePastDoesNotIndicateFuture
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34788">The fund's past performance (before and after taxes) is not necessarily an indication of 
how the fund will perform in the future.</oef:PerformancePastDoesNotIndicateFuture>
    <oef:BarChartHeading
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34789">Year-by-Year Total Returns&#x2005;as 
of 12/31 each year (%)</oef:BarChartHeading>
    <oef:BarChartClosingTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-419">&lt;p style="font-size:10.0pt; font-family:Serif; text-align:left; font-weight:normal; font-style:normal;"&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:italic; font-weight:normal; text-decoration:none;"&gt;During the periods shown in the chart:&lt;/span&gt;&lt;br/&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; font-weight:bold; text-decoration:none;"&gt;Best&lt;/span&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; font-weight:bold; text-decoration:none;"&gt; Quarter&lt;/span&gt;&lt;br/&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; font-weight:normal; text-decoration:none;"&gt;2023, 
Q4: 6.35&lt;/span&gt;&lt;br/&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; font-weight:bold; text-decoration:none;"&gt;Worst Quarter&lt;/span&gt;&lt;br/&gt;&lt;span style="font-size:10.0pt; font-family:Serif; font-style:normal; font-weight:normal; text-decoration:none;"&gt;2022, Q1: (5.63)&lt;/span&gt;&lt;/p&gt; &lt;p style="-sec-ix-redline:true;font-size:9.0pt; font-family:Serif; text-align:left; color:#000000; text-indent:-4.3pt; font-weight:normal; margin-left:8.6pt; text-decoration:none; font-style:italic;"&gt;The year-to-date total return of the fund's 
shares as of June 30, 2025 was 0.41%.&lt;/p&gt;</oef:BarChartClosingTextBlock>
    <oef:HighestQuarterlyReturnLabel
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34790">Best Quarter</oef:HighestQuarterlyReturnLabel>
    <oef:BarChartHighestQuarterlyReturnDate
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34791">2023-12-31</oef:BarChartHighestQuarterlyReturnDate>
    <oef:BarChartHighestQuarterlyReturn
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34792"
      unitRef="pure">0.0635</oef:BarChartHighestQuarterlyReturn>
    <oef:LowestQuarterlyReturnLabel
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34793">Worst Quarter</oef:LowestQuarterlyReturnLabel>
    <oef:BarChartLowestQuarterlyReturnDate
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34794">2022-03-31</oef:BarChartLowestQuarterlyReturnDate>
    <oef:BarChartLowestQuarterlyReturn
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34795"
      unitRef="pure">-0.0563</oef:BarChartLowestQuarterlyReturn>
    <oef:YearToDateReturnLabel
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34796">The year-to-date total return of the fund's 
shares as of</oef:YearToDateReturnLabel>
    <oef:BarChartYearToDateReturnDate
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34797">2025-06-30</oef:BarChartYearToDateReturnDate>
    <oef:BarChartYearToDateReturn
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34798"
      unitRef="pure">0.0041</oef:BarChartYearToDateReturn>
    <oef:PerformanceTableNarrativeTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-435">&lt;p style="font-size:10.0pt; font-family:Serif; font-style:normal; text-align:left; color:#000000; font-weight:normal; text-decoration:none;"&gt;After-tax returns are calculated 
using the historical highest individual federal marginal income tax rates, and do not reflect the impact 
of state and local taxes.  Actual after-tax returns depend on the investor's tax situation and may differ 
from those shown, and the after-tax returns shown are not relevant to investors who hold their shares 
through U.S. tax-deferred arrangements such as 401(k) plans or individual retirement accounts.  Returns 
after taxes on distributions and sale of fund shares may be higher than returns before taxes or returns 
after taxes on distributions due to an assumed tax benefit from losses on a sale of the fund's shares 
at the end of the period.&lt;/p&gt;</oef:PerformanceTableNarrativeTextBlock>
    <oef:PerformanceTableUsesHighestFederalRate
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34799">After-tax returns are calculated 
using the historical highest individual federal marginal income tax rates, and do not reflect the impact 
of state and local taxes.</oef:PerformanceTableUsesHighestFederalRate>
    <oef:PerformanceTableNotRelevantToTaxDeferred
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34800">Actual after-tax returns depend on the investor's tax situation and may differ 
from those shown, and the after-tax returns shown are not relevant to investors who hold their shares 
through U.S. tax-deferred arrangements such as 401(k) plans or individual retirement accounts.</oef:PerformanceTableNotRelevantToTaxDeferred>
    <oef:PerformanceTableExplanationAfterTaxHigher
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34801">Returns 
after taxes on distributions and sale of fund shares may be higher than returns before taxes or returns 
after taxes on distributions due to an assumed tax benefit from losses on a sale of the fund's shares 
at the end of the period.</oef:PerformanceTableExplanationAfterTaxHigher>
    <oef:AverageAnnualReturnCaption
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34802">Average Annual Total Returns 
(as of 12/31/24)</oef:AverageAnnualReturnCaption>
    <oef:AverageAnnualReturnLabel
      contextRef="Context_20250531_20250531_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34803">returns before taxes</oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20240101_20241231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34804"
      unitRef="pure">0.0096</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20200101_20241231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34805"
      unitRef="pure">0.0071</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20150101_20241231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34806"
      unitRef="pure">0.0183</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Context_20250531_20250531_AfterTaxesOnDistributionsMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34807">returns after taxes 
on distributions</oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20240101_20241231_AfterTaxesOnDistributionsMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34808"
      unitRef="pure">0.0096</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20200101_20241231_AfterTaxesOnDistributionsMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34809"
      unitRef="pure">0.0065</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20150101_20241231_AfterTaxesOnDistributionsMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34810"
      unitRef="pure">0.0169</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Context_20250531_20250531_AfterTaxesOnDistributionsAndSalesMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      id="ixv-34811">returns after taxes on distributions and 
sale of fund shares</oef:AverageAnnualReturnLabel>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20240101_20241231_AfterTaxesOnDistributionsAndSalesMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34812"
      unitRef="pure">0.0164</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20200101_20241231_AfterTaxesOnDistributionsAndSalesMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34813"
      unitRef="pure">0.0106</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20150101_20241231_AfterTaxesOnDistributionsAndSalesMember_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34814"
      unitRef="pure">0.0194</oef:AvgAnnlRtrPct>
    <oef:AverageAnnualReturnLabel
      contextRef="Context_20250531_20250531_BloombergUSMunicipalBondIndexreflectsnodeductionsforfeesexpensesortaxes31_S000000073Member_S000000073Summary1Member"
      id="ixv-34815">Bloomberg 
U.S. Municipal Bond Index</oef:AverageAnnualReturnLabel>
    <oef:IndexNoDeductionForFeesExpensesTaxes
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
      id="ixv-34816">reflects no deductions for fees, expenses or taxes</oef:IndexNoDeductionForFeesExpensesTaxes>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20240101_20241231_BloombergUSMunicipalBondIndexreflectsnodeductionsforfeesexpensesortaxes31_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34817"
      unitRef="pure">0.0105</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20200101_20241231_BloombergUSMunicipalBondIndexreflectsnodeductionsforfeesexpensesortaxes31_S000000073Member_S000000073Summary1Member"
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      id="ixv-34818"
      unitRef="pure">0.0099</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20150101_20241231_BloombergUSMunicipalBondIndexreflectsnodeductionsforfeesexpensesortaxes31_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34819"
      unitRef="pure">0.0225</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20240101_20241231_BloombergMunicipalBond7YearIndex6-8reflectsnodeductionsforfeesexpensesortaxes32_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34820"
      unitRef="pure">0.0051</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20200101_20241231_BloombergMunicipalBond7YearIndex6-8reflectsnodeductionsforfeesexpensesortaxes32_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34821"
      unitRef="pure">0.0092</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="Context_20150101_20241231_BloombergMunicipalBond7YearIndex6-8reflectsnodeductionsforfeesexpensesortaxes32_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-34822"
      unitRef="pure">0.0200</oef:AvgAnnlRtrPct>
    <dei:DocumentType contextRef="Context_20250531_20250531" id="ixv-34825">485BPOS</dei:DocumentType>
    <dei:DocumentPeriodEndDate contextRef="Context_20250531_20250531" id="ixv-34826">2025-05-31</dei:DocumentPeriodEndDate>
    <dei:EntityCentralIndexKey contextRef="Context_20250531_20250531" id="ixv-34827">0000718935</dei:EntityCentralIndexKey>
    <dei:AmendmentFlag contextRef="Context_20250531_20250531" id="ixv-34828">false</dei:AmendmentFlag>
    <dei:DocumentCreationDate contextRef="Context_20250531_20250531" id="ixv-34829">2025-09-24</dei:DocumentCreationDate>
    <oef:AnnualFundOperatingExpensesTableTextBlock
      contextRef="Context_20250531_20250531_S000000073Member_S000000073Summary1Member"
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    <oef:AnnlRtrPct
      contextRef="Context_20151231_20151231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35224"
      unitRef="pure">0.03</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20161231_20161231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35225"
      unitRef="pure">-0.003</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20171231_20171231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35226"
      unitRef="pure">0.0461</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20181231_20181231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35227"
      unitRef="pure">0.007</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20191231_20191231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35228"
      unitRef="pure">0.0695</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20201231_20201231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35229"
      unitRef="pure">0.0428</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20211231_20211231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35230"
      unitRef="pure">0.0075</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20221231_20221231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35231"
      unitRef="pure">-0.0729</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20231231_20231231_C000000110Member_S000000073Member_S000000073Summary1Member"
      decimals="INF"
      id="ixv-35232"
      unitRef="pure">0.0533</oef:AnnlRtrPct>
    <oef:AnnlRtrPct
      contextRef="Context_20241231_20241231_C000000110Member_S000000073Member_S000000073Summary1Member"
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</xbrl>
