Investor A1 [Member] Expense Example - Investor A1 [Member] - BlackRock Strategic Municipal Opportunities Fund of BlackRock Municipal Series Trust - Investor A1 Shares	May 31, 2026 USD ($)
Prospectus [Line Items]
Expense Example, with Redemption, 1 Year	$ 100
Expense Example, with Redemption, 3 Years	323
Expense Example, with Redemption, 5 Years	564
Expense Example, with Redemption, 10 Years	$ 1,255

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