As filed with the U.S. Securities and Exchange Commission on October 11, 2012
Securities Act File No. 33-08058
Investment Company Act File No. 811-04802
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM N-1A
REGISTRATION STATEMENT
UNDER
THE SECURITIES ACT OF 1933 | x | |||
Pre-Effective Amendment No. | ¨ | |||
Post-Effective Amendment No. 35 | x | |||
and/or | ||||
REGISTRATION STATEMENT | ||||
UNDER | ||||
THE INVESTMENT COMPANY ACT OF 1940 | x |
Amendment No. 36
(Check appropriate box or boxes)
BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust
(Exact Name of Registrant as Specified in Charter)
100 Bellevue Parkway
Wilmington, Delaware 19809
(Address of Principal Executive Office)
Registrants Telephone Number, including Area Code (800) 441-7762
John M. Perlowski
BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust
55 East 52nd Street, New York, New York 10055
(Name and Address of Agent for Service)
Copies to:
Counsel for the Fund: Margery K. Neale, Esq. Willkie Farr & Gallagher LLP 787 Seventh Avenue New York, New York 10019-6099 |
Benjamin Archibald, Esq. BlackRock Advisors, LLC 55 East 52nd Street New York, New York 10055 |
Continuous
(Approximate Date of Proposed Offering)
It is proposed that this filing will become effective:
x | immediately upon filing pursuant to paragraph (b) |
¨ | on (date) pursuant to paragraph (b) |
¨ | 60 days after filing pursuant to paragraph (a)(1) |
¨ | on (date) pursuant to paragraph (a)(1) |
¨ | 75 days after filing pursuant to paragraph (a)(2) |
¨ | on (date) pursuant to paragraph (a)(2) of Rule 485. |
If appropriate, check the following box:
¨ | This post-effective amendment designates a new effective date for a previously filed post-effective amendment. |
Title of Securities Being Registered: Shares of Beneficial Interest, par value $.10 per share.
SIGNATURES
Pursuant to the requirements of the Securities Act of 1933 and the Investment Company Act of 1940, the Registrant certifies that it meets all requirements for effectiveness of this Post-Effective Amendment to the Registration Statement pursuant to Rule 485(b) under the Securities Act and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of New York, and State of New York, on the 11th day of October, 2012.
BLACKROCK MUNICIPAL SERIES TRUST (REGISTRANT) on behalf of BlackRock Intermediate Municipal Fund | ||
By: | /s/ John Perlowski | |
(John Perlowski, Chief Executive Officer) |
Pursuant to the requirements of the Securities Act of 1933, this Post-Effective Amendment to the Registration Statement has been signed below by the following persons in the capacities and on the dates indicated.
Signature |
Title |
Date | ||
/s/ John Perlowski (John Perlowski) |
Chief Executive Officer (Principal Executive Officer) | October 11, 2012 | ||
/s/ Neal Andrews (Neal J. Andrews) |
Chief Financial Officer (Principal Financial and Accounting Officer) | October 11, 2012 | ||
JAMES H. BODURTHA* (James H. Bodurtha) |
Trustee | October 11, 2012 | ||
BRUCE R. BOND* (Bruce R. Bond) |
Trustee | October 11, 2012 | ||
DONALD W. BURTON* (Donald W. Burton) |
Trustee | October 11, 2012 | ||
STUART E. EIZENSTAT* (Stuart E. Eizenstat) |
Trustee | October 11, 2012 | ||
KENNETH A. FROOT* (Kenneth A. Froot) |
Trustee | October 11, 2012 | ||
ROBERT M. HERNANDEZ* (Robert M. Hernandez) |
Trustee | October 11, 2012 | ||
JOHN F. OBRIEN* (John F. OBrien) |
Trustee | October 11, 2012 | ||
ROBERTA COOPER RAMO* (Roberta Cooper Ramo) |
Trustee | October 11, 2012 | ||
DAVID H. WALSH* (David H. Walsh) |
Trustee | October 11, 2012 |
FRED G. WEISS* (Fred G. Weiss) |
Trustee | October 11, 2012 | ||
PAUL L. AUDET* (Paul L. Audet) |
Trustee and President | October 11, 2012 | ||
LAURENCE D. FINK* (Laurence D. Fink) |
Trustee | October 11, 2012 | ||
HENRY GABBAY* (Henry Gabbay) |
Trustee | October 11, 2012 |
*By: | /s/ Benjamin Archibald |
October 11, 2012 | ||||
Benjamin Archibald (Attorney-In-Fact) |
EXHIBIT INDEX
Index No. |
Description of Exhibit | |
EX-101.INS | XBRL Instance Document | |
EX-101.SCH | XBRL Taxonomy Extension Schema Document | |
EX-101.CAL | XBRL Taxonomy Extension Calculation Linkbase | |
EX-101.DEF | XBRL Taxonomy Extension Definition Linkbase | |
EX-101.LAB | XBRL Taxonomy Extension Labels Linkbase | |
EX-101.PRE | XBRL Taxonomy Extension Presentation Linkbase |
Label | Element | Value | ||||||||||
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Registrant Name | dei_EntityRegistrantName | BLACKROCK MUNICIPAL SERIES TRUST | ||||||||||
Prospectus Date | rr_ProspectusDate | Sep. 28, 2012 | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Risk/Return [Heading] | rr_RiskReturnHeading | Fund Overview Key Facts about BlackRock Intermediate Municipal Fund |
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Objective [Heading] | rr_ObjectiveHeading | Investment Objective | ||||||||||
Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | The investment objective of the BlackRock Intermediate Municipal Fund (the “Fund”) is to provide shareholders with a high level of income exempt from Federal income taxes. | ||||||||||
Expense [Heading] | rr_ExpenseHeading | Fees and Expenses of the Fund | ||||||||||
Expense Narrative [Text Block] | rr_ExpenseNarrativeTextBlock | This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the BlackRock-advised fund complex. More information about these and other discounts is available from your financial professional and in the “Details about the Share Classes” section on page 16 of the Fund’s prospectus and in the “Purchase of Shares” section on page II-69 of the Fund’s statement of additional information. | ||||||||||
Shareholder Fees Caption [Text] | rr_ShareholderFeesCaption | Shareholder Fees (fees paid directly from your investment) |
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Operating Expenses Caption [Text] | rr_OperatingExpensesCaption | Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment) |
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Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | October 1, 2013 | ||||||||||
Portfolio Turnover [Heading] | rr_PortfolioTurnoverHeading | Portfolio Turnover: | ||||||||||
Portfolio Turnover [Text Block] | rr_PortfolioTurnoverTextBlock | The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its portfolio). A higher portfolio turnover may indicate higher transaction costs and may result in higher taxes when shares are held in a taxable account. These costs, which are not reflected in annual fund operating expenses or in the example, affect the Fund’s performance. During the most recent fiscal year, the Fund’s portfolio turnover rate was 15% of the average value of its portfolio. | ||||||||||
Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 15.00% | ||||||||||
Expense Breakpoint Discounts [Text] | rr_ExpenseBreakpointDiscounts | You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $100,000 in the BlackRock-advised fund complex. | ||||||||||
Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | 100,000 | ||||||||||
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] | rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees | The Total Annual Fund Operating Expenses and the Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements do not correlate to the ratio of expenses to average net assets given in the Fund’s annual report, which does not include Acquired Fund Fees and Expenses. | ||||||||||
Expense Example [Heading] | rr_ExpenseExampleHeading | Example: | ||||||||||
Expense Example Narrative [Text Block] | rr_ExpenseExampleNarrativeTextBlock | This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain the same. Although your actual costs may be higher or lower, based on these assumptions your costs would be: | ||||||||||
Expense Example, No Redemption Narrative [Text Block] | rr_ExpenseExampleNoRedemptionNarrativeTextBlock | You will pay the following expenses if you do not redeem your shares: | ||||||||||
Strategy [Heading] | rr_StrategyHeading | Principal Investment Strategies of the Fund | ||||||||||
Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | The Fund invests primarily in a portfolio of investment grade municipal bonds. These may be obligations of a variety of issuers including states, territories and possessions of the United States, including the District of Columbia, and their political subdivisions, agencies and instrumentalities. Under normal circumstances, the Fund will invest at least 80% of its assets in municipal bonds. The Fund may invest in either fixed rate or variable rate obligations. Under normal circumstances, at least 80% of the Fund’s assets will be invested in investment grade municipal bonds. Under normal circumstances, the Fund’s dollar-weighted average maturity will be between three and ten years; however, there is no limit on the remaining maturity of each individual municipal bond investment by the Fund. | ||||||||||
Risk [Heading] | rr_RiskHeading | Principal Risks of Investing in the Fund | ||||||||||
Risk Narrative [Text Block] | rr_RiskNarrativeTextBlock | Risk is inherent in all investing. The value of your investment in the Fund, as well as the amount of return you receive on your investment, may fluctuate significantly from day to day and over time. You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. The following is a summary description of principal risks of investing in the Fund.
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Risk Lose Money [Text] | rr_RiskLoseMoney | You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. | ||||||||||
Bar Chart and Performance Table [Heading] | rr_BarChartAndPerformanceTableHeading | Performance Information | ||||||||||
Performance Narrative [Text Block] | rr_PerformanceNarrativeTextBlock | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to those of the S&P Municipal Bond Index and the S&P Intermediate Municipal Bond Index, which are relevant to the Fund because they have characteristics similar to the Fund’s investment strategies. Prior to the Investor A and Investor C Shares inception date of October 2, 2006, the returns for Investor A and Investor C Shares are based on performance of the Fund’s Institutional Shares. The returns for Investor A and Investor C Shares, however, are adjusted to reflect the distribution and service (12b-1) fees applicable to such Shares. As with all such investments, past performance (before and after taxes) is not an indication of future results. Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. However, the table includes all applicable fees and sales charges. If the Fund’s investment manager and its affiliates had not waived or reimbursed certain Fund expenses during these periods, the Fund’s returns would have been lower. Updated information on the Fund’s performance can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at 800-882-0052. | ||||||||||
Performance Information Illustrates Variability of Returns [Text] | rr_PerformanceInformationIllustratesVariabilityOfReturns | The information shows you how the Fund’s performance has varied year by year and provides some indication of the risks of investing in the Fund. | ||||||||||
Performance Availability Phone [Text] | rr_PerformanceAvailabilityPhone | 800-882-0052 | ||||||||||
Performance Availability Website Address [Text] | rr_PerformanceAvailabilityWebSiteAddress | http://www.blackrock.com/funds | ||||||||||
Performance Past Does Not Indicate Future [Text] | rr_PerformancePastDoesNotIndicateFuture | As with all such investments, past performance (before and after taxes) is not an indication of future results. | ||||||||||
Bar Chart [Heading] | rr_BarChartHeading | ANNUAL TOTAL RETURNS BlackRock Intermediate Municipal Fund As of 12/31 |
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Bar Chart Does Not Reflect Sales Loads [Text] | rr_BarChartDoesNotReflectSalesLoads | Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown. | ||||||||||
Bar Chart Closing [Text Block] | rr_BarChartClosingTextBlock | During the ten-year period shown in the bar chart, the highest return for a quarter was 7.08% (quarter ended September 30, 2009) and the lowest return for a quarter was 4.09% (quarter ended December 31, 2010). The year-to-date return as of June 30, 2012 was 4.32%. | ||||||||||
Performance Table Heading | rr_PerformanceTableHeading | As of 12/31/11 Average Annual Total Returns |
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Performance Table Does Reflect Sales Loads | rr_PerformanceTableDoesReflectSalesLoads | However, the table includes all applicable fees and sales charges. | ||||||||||
Performance Table Uses Highest Federal Rate | rr_PerformanceTableUsesHighestFederalRate | After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. | ||||||||||
Performance Table Not Relevant to Tax Deferred | rr_PerformanceTableNotRelevantToTaxDeferred | Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. | ||||||||||
Performance Table One Class of after Tax Shown [Text] | rr_PerformanceTableOneClassOfAfterTaxShown | After-tax returns are shown for Institutional Shares only, and the after-tax returns for Investor A, Investor B and Investor C Shares will vary. | ||||||||||
Performance Table Narrative | rr_PerformanceTableNarrativeTextBlock | After-tax returns are calculated using the historical highest individual Federal marginal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on the investor's tax situation and may differ from those shown, and the after-tax returns shown are not relevant to investors who hold their shares through tax-deferred arrangements such as 401(k) plans or individual retirement accounts. After-tax returns are shown for Institutional Shares only, and the after-tax returns for Investor A, Investor B and Investor C Shares will vary. | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Investor A Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 4.25% | ||||||||||
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | [1] | |||||||||
Management Fee | rr_ManagementFeesOverAssets | 0.55% | [2] | |||||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||||||
Interest Expense | rr_Component1OtherExpensesOverAssets | 0.01% | ||||||||||
Miscellaneous Other Expense | rr_Component2OtherExpensesOverAssets | 0.13% | ||||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.14% | ||||||||||
Acquired Fund Fees and Expenses | rr_AcquiredFundFeesAndExpensesOverAssets | 0.01% | [3] | |||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.95% | [3] | |||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.05%) | [2] | |||||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.90% | [2],[3] | |||||||||
1 Year | rr_ExpenseExampleYear01 | 513 | ||||||||||
3 Years | rr_ExpenseExampleYear03 | 710 | ||||||||||
5 Years | rr_ExpenseExampleYear05 | 923 | ||||||||||
10 Years | rr_ExpenseExampleYear10 | 1,537 | ||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 6.34% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 4.21% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 4.31% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Investor B Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | [4] | |||||||||
Management Fee | rr_ManagementFeesOverAssets | 0.55% | [2] | |||||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.30% | ||||||||||
Interest Expense | rr_Component1OtherExpensesOverAssets | 0.01% | ||||||||||
Miscellaneous Other Expense | rr_Component2OtherExpensesOverAssets | 0.21% | ||||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.22% | ||||||||||
Acquired Fund Fees and Expenses | rr_AcquiredFundFeesAndExpensesOverAssets | 0.01% | [3] | |||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.08% | [3] | |||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.05%) | [2] | |||||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.03% | [2],[3] | |||||||||
1 Year | rr_ExpenseExampleYear01 | 205 | ||||||||||
3 Years | rr_ExpenseExampleYear03 | 364 | ||||||||||
5 Years | rr_ExpenseExampleYear05 | 591 | ||||||||||
10 Years | rr_ExpenseExampleYear10 | 1,313 | ||||||||||
1 Year | rr_ExpenseExampleNoRedemptionYear01 | 105 | ||||||||||
3 Years | rr_ExpenseExampleNoRedemptionYear03 | 339 | ||||||||||
5 Years | rr_ExpenseExampleNoRedemptionYear05 | 591 | ||||||||||
10 Years | rr_ExpenseExampleNoRedemptionYear10 | 1,313 | ||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 10.02% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.02% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 4.69% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Investor C Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | [5] | |||||||||
Management Fee | rr_ManagementFeesOverAssets | 0.55% | [2] | |||||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||||
Interest Expense | rr_Component1OtherExpensesOverAssets | 0.01% | ||||||||||
Miscellaneous Other Expense | rr_Component2OtherExpensesOverAssets | 0.15% | ||||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.16% | ||||||||||
Acquired Fund Fees and Expenses | rr_AcquiredFundFeesAndExpensesOverAssets | 0.01% | [3] | |||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.72% | [3] | |||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.05%) | [2] | |||||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.67% | [2],[3] | |||||||||
1 Year | rr_ExpenseExampleYear01 | 270 | ||||||||||
3 Years | rr_ExpenseExampleYear03 | 537 | ||||||||||
5 Years | rr_ExpenseExampleYear05 | 929 | ||||||||||
10 Years | rr_ExpenseExampleYear10 | 2,026 | ||||||||||
1 Year | rr_ExpenseExampleNoRedemptionYear01 | 170 | ||||||||||
3 Years | rr_ExpenseExampleNoRedemptionYear03 | 537 | ||||||||||
5 Years | rr_ExpenseExampleNoRedemptionYear05 | 929 | ||||||||||
10 Years | rr_ExpenseExampleNoRedemptionYear10 | 2,026 | ||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 9.22% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 4.33% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 3.98% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Institutional Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||||
Maximum Deferred Sales Charge (Load) (as percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||||||
Management Fee | rr_ManagementFeesOverAssets | 0.55% | [2] | |||||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||||
Interest Expense | rr_Component1OtherExpensesOverAssets | 0.01% | ||||||||||
Miscellaneous Other Expense | rr_Component2OtherExpensesOverAssets | 0.14% | ||||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.15% | ||||||||||
Acquired Fund Fees and Expenses | rr_AcquiredFundFeesAndExpensesOverAssets | 0.01% | [3] | |||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 0.71% | [3] | |||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.05%) | [2] | |||||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.66% | [2],[3] | |||||||||
1 Year | rr_ExpenseExampleYear01 | 67 | ||||||||||
3 Years | rr_ExpenseExampleYear03 | 222 | ||||||||||
5 Years | rr_ExpenseExampleYear05 | 390 | ||||||||||
10 Years | rr_ExpenseExampleYear10 | 878 | ||||||||||
2002 | rr_AnnualReturn2002 | 10.41% | ||||||||||
2003 | rr_AnnualReturn2003 | 4.90% | ||||||||||
2004 | rr_AnnualReturn2004 | 3.04% | ||||||||||
2005 | rr_AnnualReturn2005 | 1.23% | ||||||||||
2006 | rr_AnnualReturn2006 | 4.04% | ||||||||||
2007 | rr_AnnualReturn2007 | 3.25% | ||||||||||
2008 | rr_AnnualReturn2008 | (4.00%) | ||||||||||
2009 | rr_AnnualReturn2009 | 13.38% | ||||||||||
2010 | rr_AnnualReturn2010 | 3.82% | ||||||||||
2011 | rr_AnnualReturn2011 | 11.32% | ||||||||||
Year to Date Return, Label | rr_YearToDateReturnLabel | year-to-date return | ||||||||||
Bar Chart, Year to Date Return, Date | rr_BarChartYearToDateReturnDate | Jun. 30, 2012 | ||||||||||
Bar Chart, Year to Date Return | rr_BarChartYearToDateReturn | 4.32% | ||||||||||
Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | highest return | ||||||||||
Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Sep. 30, 2009 | ||||||||||
Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 7.08% | ||||||||||
Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | lowest return | ||||||||||
Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Dec. 31, 2010 | ||||||||||
Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (4.09%) | ||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 11.32% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.37% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 5.02% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Return After Taxes on Distributions | Institutional Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 11.32% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.37% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 4.94% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | Return After Taxes on Distributions and Sale of Fund Shares | Institutional Shares
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 8.74% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.13% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 4.83% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | S&P Municipal Bond Index (Reflects no deduction for fees, expenses or taxes)
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 10.62% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 4.86% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 5.35% | ||||||||||
Investor and Institutional Shares | BlackRock Intermediate Municipal Fund of BlackRock Municipal Series Trust | S&P Intermediate Municipal Bond Index (Reflects no deduction for fees, expenses or taxes)
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Risk/Return: | rr_RiskReturnAbstract | |||||||||||
1 Year | rr_AverageAnnualReturnYear01 | 10.17% | ||||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.96% | ||||||||||
10 Years | rr_AverageAnnualReturnYear10 | 5.57% | ||||||||||
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