Investor A1 [Member] Annual Fund Operating Expenses - Investor A1 - BlackRock Strategic Municipal Opportunities Fund |
May 31, 2025 |
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| Prospectus [Line Items] | ||||||||
| Fee Waiver or Reimbursement over Assets, Date of Termination | June 30, 2027 | |||||||
| Investor A1 Shares | ||||||||
| Prospectus [Line Items] | ||||||||
| Management Fees (as a percentage of Assets) | 0.52% | [1],[2] | ||||||
| Distribution and Service (12b-1) Fees | 0.10% | |||||||
| Component1 Other Expenses | 0.08% | |||||||
| Component2 Other Expenses | 0.15% | |||||||
| Other Expenses (as a percentage of Assets): | 0.23% | |||||||
| Acquired Fund Fees and Expenses | 0.02% | [3] | ||||||
| Expenses (as a percentage of Assets) | 0.87% | [3] | ||||||
| Fee Waiver or Reimbursement | (0.05%) | [1],[2] | ||||||
| Net Expenses (as a percentage of Assets) | 0.82% | [1],[2] | ||||||
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