497

Dreyfus Municipal Bond Opportunity Fund (the "Registrant")

Incorporated herein by reference is a revised version of the Registrant's prospectus dated August 31, 2018, As Revised October 1, 2018 filed pursuant to Rule 497(e) under the Securities Act of 1933 (SEC Accession No. 0000797923-18-000013).

XML

Document and Entity Information	Total
Prospectus:
Document Type	497
Document Period End Date	Apr. 30, 2018
Registrant Name	DREYFUS MUNICIPAL BOND OPPORTUNITY FUND
Central Index Key	0000797923
Amendment Flag	false
Document Creation Date	Oct. 01, 2018
Document Effective Date	Oct. 01, 2018
Prospectus Date	Oct. 01, 2018
DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class A
Prospectus:
Trading Symbol	PTEBX
DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class C
Prospectus:
Trading Symbol	DMBCX
DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class Z
Prospectus:
Trading Symbol	DMBZX
DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class Y
Prospectus:
Trading Symbol	DMBYX
DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class I
Prospectus:
Trading Symbol	DMBVX

XML

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND

Fund Summary

Investment Objective

The fund seeks to maximize current income exempt from federal income tax to the extent consistent with the preservation of capital.

Fees and Expenses

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or shares of other funds in the Dreyfus Family of Funds that are subject to a sales charge. More information about sales charges, including these and other discounts and waivers, is available from your financial professional and in the Shareholder Guide section beginning on page 9 of the prospectus and in the How to Buy Shares section and the Additional Information About How to Buy Shares section beginning on page II-1 and page III-1, respectively, of the fund's Statement of Additional Information.

Shareholder Fees (fees paid directly from your investment)

Shareholder Fees - DREYFUS MUNICIPAL BOND OPPORTUNITY FUND	Class A		Class C	Class I	Class Y	Class Z
Maximum sales charge (load) imposed on purchases (as a percentage of offering price)	4.50%		none	none	none	none
Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)	none	[1]	1.00%	none	none	none

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Annual Fund Operating Expenses - DREYFUS MUNICIPAL BOND OPPORTUNITY FUND	Class A	Class C	Class I	Class Y	Class Z
Management fees	0.55%	0.55%	0.55%	0.55%	0.55%
Distribution (12b-1) fees	none	0.75%	none	none	none
Other expenses (including shareholder services fees)	0.38%	0.40%	0.15%	0.15%	0.32%
Total annual fund operating expenses	0.93%	1.70%	0.70%	0.70%	0.87%

Example

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 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:

Expense Example - DREYFUS MUNICIPAL BOND OPPORTUNITY FUND - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	541	733	942	1,542
Class C	273	536	923	2,009
Class I	72	224	390	871
Class Y	72	224	390	871
Class Z	89	278	482	1,073

You would pay the following expenses if you did not redeem your shares:

Expense Example No Redemption - DREYFUS MUNICIPAL BOND OPPORTUNITY FUND - USD ($)	1 Year	3 Years	5 Years	10 Years
Class A	541	733	942	1,542
Class C	173	536	923	2,009
Class I	72	224	390	871
Class Y	72	224	390	871
Class Z	89	278	482	1,073

Portfolio Turnover

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 26.94% of the average value of its portfolio.

Principal Investment Strategy

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 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, and certain other specified securities.

The fund invests at least 70% of its assets in municipal bonds rated, at the time of purchase, investment grade (i.e., Baa/BBB or higher) or the unrated equivalent as determined by The Dreyfus Corporation. For additional yield, the fund may invest up to 30% of its assets in municipal bonds rated below investment grade ("high yield" or "junk" bonds) or the unrated equivalent as determined by The Dreyfus Corporation. The dollar-weighted average maturity of the fund's portfolio normally exceeds ten years, but the fund may invest without regard to maturity or duration. A bond's maturity is 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. Duration is an indication of an investment's "interest rate risk," or how sensitive a bond or the fund's portfolio may be to changes in interest rates.

The fund's portfolio managers focus on identifying undervalued sectors and securities. To select municipal bonds for the fund, the fund's portfolio managers use fundamental credit analysis to estimate the relative value and attractiveness of various sectors and securities and actively trade among various sectors based on their apparent relative values.

Although the fund seeks to provide income exempt from federal income tax, the fund may invest without limitation in municipal bonds the income from which is subject to the federal alternative minimum tax.

Principal Risks

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.

·Municipal securities risk. The amount of public information available about municipal securities is generally less than that for corporate equities or bonds. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or 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 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.

·Interest rate risk. 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. 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. 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. The change in the value of a fixed-income security or portfolio can be approximated by multiplying its duration by a change in interest rates. For example, the market price of a fixed-income security with a duration of three years would be expected to decline 3% if interest rates rose 1%. Conversely, the market price of the same security would be expected to increase 3% if interest rates fell 1%. Unlike investment grade bonds, however, the prices of high yield ("junk") bonds may fluctuate unpredictably and not necessarily inversely with changes in interest rates. Risks associated with rising interest rates are heightened given that the Federal Reserve has raised the federal funds rate several times in recent periods and has signaled additional increases in the near future.

·Credit risk. 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.

·High yield securities risk. 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. The prices of high yield securities can fall in response to bad news about the issuer or its industry, or the economy in general, to a greater extent than those of higher rated securities.

·Liquidity risk. 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 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. Liquidity risk also may refer to the risk that the fund will not be able to pay redemption proceeds within the allowable time period stated in this prospectus because of unusual market conditions, an unusually high volume of redemption requests, or other reasons. To meet redemption requests, the fund may be forced to sell securities at an unfavorable time and/or under unfavorable conditions, which may adversely affect the fund's share price.

Performance

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 Class A shares from year to year. Sales charges, if any, are not reflected in the bar chart, and, if those charges were included, returns would have been less than those shown. The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance. 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.dreyfus.com.

Year-by-Year Total Returns as of 12/31 each year (%) Class A

Best Quarter
Q3, 2009: 8.05%

Worst Quarter
Q4, 2010: -5.46%

The year-to-date total return of the fund's Class A shares as of June 30, 2018 was -0.10%.

Average Annual Total Returns (as of 12/31/17)

After-tax performance is shown only for Class A shares. After-tax performance of the fund's other share classes will vary. 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.

For the fund's Class I and Y shares, periods prior to the inception date reflect the performance of the fund's Class A shares, without reflecting any applicable sales charges for Class A shares. Such performance figures have not been adjusted to reflect applicable class fees and expenses. Each share class is invested in the same portfolio of securities, and the annual returns would have differed only to the extent that the classes do not have the same expenses.

Average Annual Returns - DREYFUS MUNICIPAL BOND OPPORTUNITY FUND	Average Annual Returns, 1 Year	Average Annual Returns, 5 Years	Average Annual Returns, 10 Years	Average Annual Returns, Inception Date
Class A	1.01%	2.14%	3.52%
Class C	3.93%	2.31%	3.23%
Class I	5.89%	3.16%	4.03%	Aug. 31, 2016
Class Y	5.83%	3.09%	3.99%	Aug. 31, 2016
Class Z	5.80%	3.15%	4.05%
After Taxes on Distributions | Class A	1.01%	2.14%	3.51%
After Taxes on Distributions and Sale of Fund Shares | Class A	1.86%	2.37%	3.54%
Bloomberg Barclays U.S. Municipal Bond Index reflects no deductions for fees, expenses or taxes	5.45%	3.02%	4.46%

[1] Class A shares bought without an initial sales charge as part of an investment of $1 million or more may be charged a deferred sales charge of 1.00% if redeemed within one year.

XML

Label

Element

Value

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND

Risk/Return:

rr_RiskReturnAbstract

Risk/Return [Heading]

rr_RiskReturnHeading

Fund Summary

Objective [Heading]

rr_ObjectiveHeading

Investment Objective

Objective, Primary [Text Block]

rr_ObjectivePrimaryTextBlock

The fund seeks to maximize current income exempt from federal income tax to the extent consistent with the preservation of capital.

Expense [Heading]

rr_ExpenseHeading

Fees and Expenses

Expense Narrative [Text Block]

rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or shares of other funds in the Dreyfus Family of Funds that are subject to a sales charge. More information about sales charges, including these and other discounts and waivers, is available from your financial professional and in the Shareholder Guide section beginning on page 9 of the prospectus and in the How to Buy Shares section and the Additional Information About How to Buy Shares section beginning on page II-1 and page III-1, respectively, of the fund's Statement of Additional Information.

Shareholder Fees Caption [Text]

rr_ShareholderFeesCaption

Shareholder Fees (fees paid directly from your investment)

Operating Expenses Caption [Text]

rr_OperatingExpensesCaption

Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)

Portfolio Turnover [Heading]

rr_PortfolioTurnoverHeading

Portfolio Turnover

Portfolio Turnover [Text Block]

rr_PortfolioTurnoverTextBlock

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 26.94% of the average value of its portfolio.

Portfolio Turnover, Rate

rr_PortfolioTurnoverRate

26.94%

Expense Breakpoint Discounts [Text]

rr_ExpenseBreakpointDiscounts

You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $50,000 in the fund or shares of other funds in the Dreyfus Family of Funds that are subject to a sales charge.

Expense Breakpoint, Minimum Investment Required [Amount]

rr_ExpenseBreakpointMinimumInvestmentRequiredAmount

$ 50,000

Expense Example [Heading]

rr_ExpenseExampleHeading

Example

Expense Example Narrative [Text Block]

rr_ExpenseExampleNarrativeTextBlock

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 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:

Expense Example, No Redemption, By Year, Caption [Text]

rr_ExpenseExampleNoRedemptionByYearCaption

You would pay the following expenses if you did not redeem your shares:

Strategy [Heading]

rr_StrategyHeading

Principal Investment Strategy

Strategy Narrative [Text Block]

rr_StrategyNarrativeTextBlock

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 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, and certain other specified securities.

The fund invests at least 70% of its assets in municipal bonds rated, at the time of purchase, investment grade (i.e., Baa/BBB or higher) or the unrated equivalent as determined by The Dreyfus Corporation. For additional yield, the fund may invest up to 30% of its assets in municipal bonds rated below investment grade ("high yield" or "junk" bonds) or the unrated equivalent as determined by The Dreyfus Corporation. The dollar-weighted average maturity of the fund's portfolio normally exceeds ten years, but the fund may invest without regard to maturity or duration. A bond's maturity is 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. Duration is an indication of an investment's "interest rate risk," or how sensitive a bond or the fund's portfolio may be to changes in interest rates.

The fund's portfolio managers focus on identifying undervalued sectors and securities. To select municipal bonds for the fund, the fund's portfolio managers use fundamental credit analysis to estimate the relative value and attractiveness of various sectors and securities and actively trade among various sectors based on their apparent relative values.

Although the fund seeks to provide income exempt from federal income tax, the fund may invest without limitation in municipal bonds the income from which is subject to the federal alternative minimum tax.

Risk [Heading]

rr_RiskHeading

Principal Risks

Risk Narrative [Text Block]

rr_RiskNarrativeTextBlock

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.

·Municipal securities risk. The amount of public information available about municipal securities is generally less than that for corporate equities or bonds. Special factors, such as legislative changes, and state and local economic and business developments, may adversely affect the yield and/or 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 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.

·Interest rate risk. 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. 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. 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. The change in the value of a fixed-income security or portfolio can be approximated by multiplying its duration by a change in interest rates. For example, the market price of a fixed-income security with a duration of three years would be expected to decline 3% if interest rates rose 1%. Conversely, the market price of the same security would be expected to increase 3% if interest rates fell 1%. Unlike investment grade bonds, however, the prices of high yield ("junk") bonds may fluctuate unpredictably and not necessarily inversely with changes in interest rates. Risks associated with rising interest rates are heightened given that the Federal Reserve has raised the federal funds rate several times in recent periods and has signaled additional increases in the near future.

·Credit risk. 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.

·High yield securities risk. 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. The prices of high yield securities can fall in response to bad news about the issuer or its industry, or the economy in general, to a greater extent than those of higher rated securities.

·Liquidity risk. 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 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. Liquidity risk also may refer to the risk that the fund will not be able to pay redemption proceeds within the allowable time period stated in this prospectus because of unusual market conditions, an unusually high volume of redemption requests, or other reasons. To meet redemption requests, the fund may be forced to sell securities at an unfavorable time and/or under unfavorable conditions, which may adversely affect the fund's share price.

Risk Lose Money [Text]

rr_RiskLoseMoney

The fund's share price fluctuates, sometimes dramatically, which means you could lose money.

Risk Not Insured Depository Institution [Text]

rr_RiskNotInsuredDepositoryInstitution

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.

Bar Chart and Performance Table [Heading]

rr_BarChartAndPerformanceTableHeading

Performance

Performance Narrative [Text Block]

rr_PerformanceNarrativeTextBlock

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 Class A shares from year to year. Sales charges, if any, are not reflected in the bar chart, and, if those charges were included, returns would have been less than those shown. The table compares the average annual total returns of the fund's shares to those of a broad measure of market performance. 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.dreyfus.com.

Performance Information Illustrates Variability of Returns [Text]

rr_PerformanceInformationIllustratesVariabilityOfReturns

The following bar chart and table provide some indication of the risks of investing in the fund.

Performance Availability Website Address [Text]

rr_PerformanceAvailabilityWebSiteAddress

www.dreyfus.com

Performance Past Does Not Indicate Future [Text]

rr_PerformancePastDoesNotIndicateFuture

The fund's past performance (before and after taxes) is not necessarily an indication of how the fund will perform in the future.

Bar Chart [Heading]

rr_BarChartHeading

Year-by-Year Total Returns as of 12/31 each year (%) Class A

Bar Chart Does Not Reflect Sales Loads [Text]

rr_BarChartDoesNotReflectSalesLoads

Sales charges, if any, are not reflected in the bar chart, and, if those charges were included, returns would have been less than those shown.

Bar Chart Closing [Text Block]

rr_BarChartClosingTextBlock

Best Quarter
Q3, 2009: 8.05%

Worst Quarter
Q4, 2010: -5.46%

The year-to-date total return of the fund's Class A shares as of June 30, 2018 was -0.10%.

Year to Date Return, Label

rr_YearToDateReturnLabel

year-to-date total return

Bar Chart, Year to Date Return, Date

rr_BarChartYearToDateReturnDate

Jun. 30, 2018

Bar Chart, Year to Date Return

rr_BarChartYearToDateReturn

(0.10%)

Highest Quarterly Return, Label

rr_HighestQuarterlyReturnLabel

Best Quarter

Highest Quarterly Return, Date

rr_BarChartHighestQuarterlyReturnDate

Sep. 30, 2009

Highest Quarterly Return

rr_BarChartHighestQuarterlyReturn

8.05%

Lowest Quarterly Return, Label

rr_LowestQuarterlyReturnLabel

Worst Quarter

Lowest Quarterly Return, Date

rr_BarChartLowestQuarterlyReturnDate

Dec. 31, 2010

Lowest Quarterly Return

rr_BarChartLowestQuarterlyReturn

(5.46%)

Index No Deduction for Fees, Expenses, Taxes [Text]

rr_IndexNoDeductionForFeesExpensesTaxes

reflects no deductions for fees, expenses or taxes

Performance Table Uses Highest Federal Rate

rr_PerformanceTableUsesHighestFederalRate

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.

Performance Table Not Relevant to Tax Deferred

rr_PerformanceTableNotRelevantToTaxDeferred

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.

Performance Table One Class of after Tax Shown [Text]

rr_PerformanceTableOneClassOfAfterTaxShown

After-tax performance is shown only for Class A shares. After-tax performance of the fund's other share classes will vary.

Performance Table Explanation after Tax Higher

rr_PerformanceTableExplanationAfterTaxHigher

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.

Performance Table Narrative

rr_PerformanceTableNarrativeTextBlock

After-tax performance is shown only for Class A shares. After-tax performance of the fund's other share classes will vary. 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.

For the fund's Class I and Y shares, periods prior to the inception date reflect the performance of the fund's Class A shares, without reflecting any applicable sales charges for Class A shares. Such performance figures have not been adjusted to reflect applicable class fees and expenses. Each share class is invested in the same portfolio of securities, and the annual returns would have differed only to the extent that the classes do not have the same expenses.

Caption

rr_AverageAnnualReturnCaption

Average Annual Total Returns (as of 12/31/17)

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Bloomberg Barclays U.S. Municipal Bond Index reflects no deductions for fees, expenses or taxes

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.45%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.02%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

4.46%

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class A

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

4.50%

Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

^[1]

Management fees

rr_ManagementFeesOverAssets

0.55%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.38%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.93%

Expenses Deferred Charges [Text Block]

rr_ExpensesDeferredChargesTextBlock

Class A shares bought without an initial sales charge as part of an investment of $1 million or more may be charged a deferred sales charge of 1.00% if redeemed within one year.

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 541

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

733

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

942

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,542

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

541

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

733

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

942

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,542

Annual Return 2008

rr_AnnualReturn2008

(8.71%)

Annual Return 2009

rr_AnnualReturn2009

15.78%

Annual Return 2010

rr_AnnualReturn2010

1.05%

Annual Return 2011

rr_AnnualReturn2011

10.68%

Annual Return 2012

rr_AnnualReturn2012

7.47%

Annual Return 2013

rr_AnnualReturn2013

(3.87%)

Annual Return 2014

rr_AnnualReturn2014

11.25%

Annual Return 2015

rr_AnnualReturn2015

3.59%

Annual Return 2016

rr_AnnualReturn2016

(0.59%)

Annual Return 2017

rr_AnnualReturn2017

5.74%

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.01%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.14%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.52%

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class A | After Taxes on Distributions

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.01%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.14%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.51%

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class A | After Taxes on Distributions and Sale of Fund Shares

Risk/Return:

rr_RiskReturnAbstract

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

1.86%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.37%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.54%

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class C

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

1.00%

Management fees

rr_ManagementFeesOverAssets

0.55%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

0.75%

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.40%

Total annual fund operating expenses

rr_ExpensesOverAssets

1.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 273

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

536

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

923

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

2,009

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

173

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

536

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

923

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 2,009

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

3.93%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

2.31%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.23%

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class I

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.55%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.15%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

224

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

390

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

871

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

72

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

224

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

390

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 871

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.89%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.16%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

4.03%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 31, 2016

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class Y

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.55%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.15%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.70%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 72

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

224

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

390

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

871

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

72

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

224

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

390

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 871

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.83%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.09%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

3.99%

Average Annual Returns, Inception Date

rr_AverageAnnualReturnInceptionDate

Aug. 31, 2016

DREYFUS MUNICIPAL BOND OPPORTUNITY FUND | Class Z

Risk/Return:

rr_RiskReturnAbstract

Maximum sales charge (load) imposed on purchases (as a percentage of offering price)

rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice

none

Maximum deferred sales charge (load) (as a percentage of lower of purchase or sale price)

rr_MaximumDeferredSalesChargeOverOfferingPrice

none

Management fees

rr_ManagementFeesOverAssets

0.55%

Distribution (12b-1) fees

rr_DistributionAndService12b1FeesOverAssets

none

Other expenses (including shareholder services fees)

rr_OtherExpensesOverAssets

0.32%

Total annual fund operating expenses

rr_ExpensesOverAssets

0.87%

Expense Example, with Redemption, 1 Year

rr_ExpenseExampleYear01

$ 89

Expense Example, with Redemption, 3 Years

rr_ExpenseExampleYear03

278

Expense Example, with Redemption, 5 Years

rr_ExpenseExampleYear05

482

Expense Example, with Redemption, 10 Years

rr_ExpenseExampleYear10

1,073

Expense Example, No Redemption, 1 Year

rr_ExpenseExampleNoRedemptionYear01

89

Expense Example, No Redemption, 3 Years

rr_ExpenseExampleNoRedemptionYear03

278

Expense Example, No Redemption, 5 Years

rr_ExpenseExampleNoRedemptionYear05

482

Expense Example, No Redemption, 10 Years

rr_ExpenseExampleNoRedemptionYear10

$ 1,073

Average Annual Returns, 1 Year

rr_AverageAnnualReturnYear01

5.80%

Average Annual Returns, 5 Years

rr_AverageAnnualReturnYear05

3.15%

Average Annual Returns, 10 Years

rr_AverageAnnualReturnYear10

4.05%

[1] Class A shares bought without an initial sales charge as part of an investment of $1 million or more may be charged a deferred sales charge of 1.00% if redeemed within one year.

XML

Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Prospectus Date	rr_ProspectusDate	Oct. 01, 2018