Label	Element	Value
Dreyfus High Yield Municipal Bond Fund
Risk/Return:	rr_RiskReturnAbstract
Supplement [Text Block]	ck0000878092_SupplementTextBlock	May 1, 2018 DREYFUS MUNICIPAL FUNDS, INC. - DREYFUS HIGH YIELD MUNICIPAL BOND FUND (Class A, C, I, Y and Z Shares) Supplement to Current Summary Prospectus and Prospectus dated December 29, 2017
Risk/Return [Heading]	rr_RiskReturnHeading	Dreyfus High Yield Municipal Bond Fund
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following information supplements and supersedes any contrary information contained in the fund’s summary prospectus and prospectus. As of May 1, 2018, the fund no longer assesses a redemption fee on redemptions or exchanges of fund shares. The fund reserves the right to reimpose a redemption fee in the future, upon appropriate notice.

This table describes the fees and expenses that you may pay if you buy and hold shared 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 $[_____] in [name of fund family] funds. Include the narrative explanations in the order indicated. A Fund may modify the narrative explanations if the explanation contains comparable information to that shown. The narrative explanation regarding sales charge discounts is only required by a Fund that offers such discounts and should specify the minimum level of investment required to qualify for a discount. Modify the narrative explanation to state that Fund shares are sold on a national securities exchange at the end of the time periods indicated, and that brokerage commissions for buying and selling Fund shares through a broker are not reflected.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Form
-Number N-1A
-Chapter A
-Section 3
-Subsection instructions
-Paragraph 1
-Subparagraph b

Name:	rr_ExpenseNarrativeTextBlock
Namespace Prefix:	rr_
Data Type:	nonnum:textBlockItemType
Balance Type:	na
Period Type:	duration