Label

Element

Value

Risk/Return:

rr_RiskReturnAbstract

Registrant Name

dei_EntityRegistrantName

FEDERATED MUNICIPAL BOND FUND INC

Prospectus Date

rr_ProspectusDate

May 31, 2019

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

IMPORTANT INFORMATION REGARDING
THE FEDERATED HERMES FUNDS*

SUPPLEMENT TO CURRENT SUMMARY PROSPECTUSES, PROSPECTUSES AND STATEMENTS OF ADDITIONAL INFORMATION

* The Federated Hermes Funds include the below listed registrants and funds (including all share classes)

On February 13, 2020, in connection with Federated Investors, Inc.'s corporate name change to Federated Hermes, Inc., which became effective January 31, 2020, the Boards of Directors/Trustees (the "Boards") of the Federated Hermes funds listed below (the "Funds") approved changing each Fund's name to replace "Federated" with "Federated Hermes." In addition, the Boards approved changing each Fund's registrant name (the "Registrant") as noted below. There are no changes in fund operations or investment policies as a result of the name changes. The Fund and Registrant name changes will be effective at the close of business on June 26, 2020.

CURRENT REGISTRANT/FUND NAME	NEW REGISTRANT/FUND NAME
Federated Municipal Bond Fund, Inc.	Federated Hermes Municipal Bond Fund, Inc.

Federated Hermes Municipal Bond Fund, Inc.

Risk/Return:

rr_RiskReturnAbstract

Supplement to Prospectus [Text Block]

rr_SupplementToProspectusTextBlock

IMPORTANT INFORMATION REGARDING
THE FEDERATED HERMES FUNDS*

SUPPLEMENT TO CURRENT SUMMARY PROSPECTUSES, PROSPECTUSES AND STATEMENTS OF ADDITIONAL INFORMATION

* The Federated Hermes Funds include the below listed registrants and funds (including all share classes)

On February 13, 2020, in connection with Federated Investors, Inc.'s corporate name change to Federated Hermes, Inc., which became effective January 31, 2020, the Boards of Directors/Trustees (the "Boards") of the Federated Hermes funds listed below (the "Funds") approved changing each Fund's name to replace "Federated" with "Federated Hermes." In addition, the Boards approved changing each Fund's registrant name (the "Registrant") as noted below. There are no changes in fund operations or investment policies as a result of the name changes. The Fund and Registrant name changes will be effective at the close of business on June 26, 2020.

CURRENT REGISTRANT/FUND NAME	NEW REGISTRANT/FUND NAME
Federated Municipal Bond Fund, Inc.	Federated Hermes Municipal Bond Fund, Inc.