Investor A C and Institutional [Member] Investment Strategy - Investor A, C and Institutional - BlackRock Pennsylvania Municipal Bond Fund	May 31, 2026
Prospectus [Line Items]
Strategy [Heading]	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	The Fund invests primarily in a portfolio of long-term investment grade Pennsylvania municipal bonds. Pennsylvania municipal bonds are debt obligations issued by or on behalf of a governmental entity in Pennsylvania or other qualifying issuer that pay interest that, in the opinion of bond counsel, is excludable from gross income for Federal income tax purposes (except that interest may be includable in taxable income for purposes of the Federal alternative minimum tax) and exempt from Pennsylvania personal income taxes. These may be obligations of a variety of issuers including governmental entities in Pennsylvania and issuers located in Puerto Rico, the U.S. Virgin Islands and Guam. Under normal circumstances, the Fund will invest at least 80% of its assets in Pennsylvania municipal bonds. For the purposes of the foregoing 80% policy, “assets” are the Fund’s net assets, plus the amount of any borrowings for investment purposes. The Fund’s investments in derivatives will be counted toward the foregoing 80% policy to the extent that they provide investment exposure to the securities included within that policy or to one or more market risk factors associated with such securities. At least 80% of the Fund’s assets will be invested in investment grade securities. Investment grade securities are securities which are rated in the four highest categories by at least one of the major rating agencies or determined by the management team to be of similar quality. When choosing investments, Fund management considers various factors, including the credit quality of issuers, yield analysis, maturity analysis and the call features of the obligations. Under normal circumstances, the Fund’s weighted average maturity will be more than ten years. The Fund may leverage its assets through the use of proceeds received through tender option bond transactions. In a tender option bond transaction, the Fund transfers municipal bonds or other municipal securities into a special purpose entity (a “TOB Trust”). A TOB Trust typically issues two classes of beneficial interests: short-term floating rate interests (“TOB Floaters”), which are sold to third party investors, and residual inverse floating rate interests (“TOB Residuals”), which are generally issued to the Fund. The Fund may invest in TOB Residuals and may also invest in TOB Floaters. The Fund will look through to the underlying municipal bond held by a TOB Trust for purposes of the Fund’s 80% policy.

The Fund invests primarily in a portfolio of long-term investment grade Pennsylvania municipal bonds. Pennsylvania municipal bonds are debt obligations issued by or on behalf of a governmental entity in Pennsylvania or other qualifying issuer that pay interest that, in the opinion of bond counsel, is excludable from gross income for Federal income tax purposes (except that interest may be includable in taxable income for purposes of the Federal alternative minimum tax) and exempt from Pennsylvania personal income taxes. These may be obligations of a variety of issuers including governmental entities in Pennsylvania and issuers located in Puerto Rico, the U.S. Virgin Islands and Guam. Under normal circumstances, the Fund will invest at least 80% of its assets in Pennsylvania municipal bonds. For the purposes of the foregoing 80% policy, “assets” are the Fund’s net assets, plus the amount of any borrowings for investment purposes. The Fund’s investments in derivatives will be counted toward the foregoing 80% policy to the extent that they provide investment exposure to the securities included within that policy or to one or more market risk factors associated with such securities. At least 80% of the Fund’s assets will be invested in investment grade securities. Investment grade securities are securities which are rated in the four highest categories by at least one of the major rating agencies or determined by the management team to be of similar quality. When choosing investments, Fund management considers various factors, including the credit quality of issuers, yield analysis, maturity analysis and the call features of the obligations. Under normal circumstances, the Fund’s weighted average maturity will be more than ten years.

The Fund may leverage its assets through the use of proceeds received through tender option bond transactions. In a tender option bond transaction, the Fund transfers municipal bonds or other municipal securities into a special purpose entity (a “TOB Trust”). A TOB Trust typically issues two classes of beneficial interests: short-term floating rate interests (“TOB Floaters”), which are sold to third party investors, and residual inverse floating rate interests (“TOB Residuals”), which are generally issued to the Fund. The Fund may invest in TOB Residuals and may also invest in TOB Floaters. The Fund will look through to the underlying municipal bond held by a TOB Trust for purposes of the Fund’s 80% policy.