Investor A1 [Member] Expense Example - Investor A1 - BlackRock Strategic Municipal Opportunities Fund - Investor A1 Shares	May 31, 2025 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 84
Expense Example, with Redemption, 3 Years	273
Expense Example, with Redemption, 5 Years	477
Expense Example, with Redemption, 10 Years	$ 1,068

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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