Label | Element | Value | ||||||||
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BlackRock Real Estate Securities Fund | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk/Return [Heading] | rr_RiskReturnHeading | Fund Overview Key Facts About BlackRock Real Estate Securities Fund | ||||||||
Objective [Heading] | rr_ObjectiveHeading | Investment Objective | ||||||||
Objective, Primary [Text Block] | rr_ObjectivePrimaryTextBlock | The investment objective of BlackRock Real Estate Securities Fund (the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek total return comprised of long-term growth of capital and dividend income.
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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, hold and sell shares of the Fund. You may pay other fees, such as brokerage commissions and other fees to your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock Advisors, LLC (“BlackRock”) and its affiliates) (each, a “Financial Intermediary”), which are not reflected in the table and example below. You may qualify for sales charge discounts if you and your family invest, or agree to invest in the future, at least $25,000 in the fund complex advised by BlackRock or its affiliates. More information about these and other discounts is available from your Financial Intermediary and in the “Details About the Share Classes” and the “Intermediary-Defined Sales Charge Waiver Policies” sections on pages 23 and A-1, respectively, of the Fund’s prospectus and in the “Purchase of Shares” section on page II-90 of Part II of the Fund’s Statement of Additional Information.
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Shareholder Fees Caption [Text] | rr_ShareholderFeesCaption | Shareholder Fees (fees paid directly from your investment) | ||||||||
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) | ||||||||
Fee Waiver or Reimbursement over Assets, Date of Termination | rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination | June 30, 2025 | ||||||||
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 rate 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 65% of the average value of its portfolio.
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Portfolio Turnover, Rate | rr_PortfolioTurnoverRate | 65.00% | ||||||||
Expenses Deferred Charges [Text Block] | rr_ExpensesDeferredChargesTextBlock | A contingent deferred sales charge (“CDSC”) of 1.00% is assessed on certain redemptions of Investor A Shares made within 18 months after purchase where no initial sales charge was paid at the time of purchase as part of an investment of $1,000,000 or more. | ||||||||
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 $25,000 in the fund complex advised by BlackRock or its affiliates. | ||||||||
Expense Breakpoint, Minimum Investment Required [Amount] | rr_ExpenseBreakpointMinimumInvestmentRequiredAmount | $ 25,000 | ||||||||
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:
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Expense Example, No Redemption, By Year, Caption [Text] | rr_ExpenseExampleNoRedemptionByYearCaption | You would pay the following expenses if you did not redeem your shares: | ||||||||
Strategy [Heading] | rr_StrategyHeading | Principal Investment Strategies of the Fund | ||||||||
Strategy Narrative [Text Block] | rr_StrategyNarrativeTextBlock | Under normal conditions, the Fund invests at least 80% of its net assets plus any borrowings for investment purposes (measured at the time of purchase) in a portfolio of equity investments in issuers that are primarily engaged in or related to the real estate industry inside the United States. An issuer is primarily engaged in or related to the real estate industry if it derives at least 50% of its gross revenues or net profits from the ownership, development, construction, financing, management or sale of commercial, industrial or residential real estate or interests therein or has 50% of its assets in real estate or real estate interests. The Fund may invest up to 20% of its net assets plus any borrowings for investment purposes (measured at the time of purchase) in a portfolio of equity investments in issuers that are primarily engaged in or related to the real estate industry outside the United States and fixed-income investments, such as government, corporate and bank debt obligations. Real estate industry companies may include real estate investment trusts (“REITs”), REIT-like structures, or real estate operating companies whose businesses and services are related to the real estate industry. The Fund primarily buys common stock but also can invest in preferred stock and convertible securities. The Fund concentrates its investments in securities of issuers in the real estate industry. The Fund is classified as non-diversified under the Investment Company Act of 1940, as amended.
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Strategy Portfolio Concentration [Text] | rr_StrategyPortfolioConcentration | Under normal conditions, the Fund invests at least 80% of its net assets plus any borrowings for investment purposes (measured at the time of purchase) in a portfolio of equity investments in issuers that are primarily engaged in or related to the real estate industry inside the United States. | ||||||||
Risk [Heading] | rr_RiskHeading | Principal Risks of Investing in the Fund | ||||||||
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 that of the FTSE Nareit All Equity REITs Net Index. To the extent that dividends and distributions have been paid by the Fund, the performance information for the Fund in the chart and table assumes reinvestment of the dividends and distributions. 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 BlackRock 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, including its current net asset value, can be obtained by visiting www.blackrock.com or can be obtained by phone at (800) 882-0052.
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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 | www.blackrock.com | ||||||||
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 | Investor A Shares ANNUAL TOTAL RETURNS BlackRock Real Estate Securities Fund As of 12/31 | ||||||||
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 18.19% (quarter ended December 31, 2023) and the lowest return for a quarter was -24.07% (quarter ended March 31, 2020). The year-to-date return as of March 31, 2023 was -1.77%.
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Performance Table Heading | rr_PerformanceTableHeading | For the periods ended 12/31/23 Average Annual Total Returns | ||||||||
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 Investor A Shares only, and the after-tax returns for Investor C and Institutional 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 Investor A Shares only, and the after-tax returns for Investor C and Institutional Shares will vary.
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BlackRock Real Estate Securities Fund | Risk Nondiversified Status [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Non-Diversification Risk — The Fund is a non-diversified fund. Because the Fund may invest in securities of a smaller number of issuers, it may be more exposed to the risks associated with and developments affecting an individual issuer than a fund that invests more widely. |
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BlackRock Real Estate Securities Fund | Risk Lose Money [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments. | ||||||||
BlackRock Real Estate Securities Fund | Real Estate Related Securities Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Real Estate-Related Securities Risk — The main risk of real estate-related securities is that the value of the underlying real estate may go down. Many factors may affect real estate values. These factors include both the general and local economies, vacancy rates, changes in rent schedules, tenant bankruptcies, the ability to re-lease space under expiring leases on attractive terms, the amount of new construction in a particular area, the laws and regulations (including zoning, environmental and tax laws) affecting real estate and the costs of owning, maintaining and improving real estate. The availability of mortgage financing and changes in interest rates may also affect real estate values. If the Fund’s real estate-related investments are concentrated in one geographic area or in one property type, the Fund will be particularly subject to the risks associated with that area or property type. Many issuers of real estate-related securities are highly leveraged, which increases the risk to holders of such securities. The value of the securities the Fund buys will not necessarily track the value of the underlying investments of the issuers of such securities. In addition, certain issuers of real estate-related securities may have developed or commenced development on properties and may develop additional properties in the future. Real estate development involves significant risks in addition to those involved in the ownership and operation of established properties. Real estate securities may have limited diversification and are, therefore, subject to risks inherent in operating and financing a limited number of projects. Real estate securities are also subject to heavy cash flow dependency and defaults by borrowers or tenants.
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BlackRock Real Estate Securities Fund | REIT Investment Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ REIT Investment Risk — Investments in REITs involve unique risks. REITs may have limited financial resources, may trade less frequently and in limited volume, may engage in dilutive offerings of securities and may be more volatile than other securities. REIT issuers may also fail to maintain their exemptions from investment company registration or fail to qualify for the “dividends paid deduction” under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), which allows REITs to reduce their corporate taxable income for dividends paid to their shareholders. |
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BlackRock Real Estate Securities Fund | Equity Securities Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Equity Securities Risk — Stock markets are volatile. The price of equity securities fluctuates based on changes in a company’s financial condition and overall market and economic conditions. |
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BlackRock Real Estate Securities Fund | Concentration Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Concentration Risk — The Fund’s strategy of concentrating in the real estate industry means that its performance will be closely tied to the performance of a particular market segment. The Fund’s concentration in these companies may present more risks than if it were broadly diversified over numerous industries and sectors of the economy. A downturn in these companies would have a larger impact on the Fund than on a mutual fund that does not concentrate in such companies. At times, the performance of these companies will lag the performance of other industries or the broader market as a whole. In addition, the real estate industry has historically experienced substantial price volatility. |
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BlackRock Real Estate Securities Fund | Convertible Securities Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Convertible Securities Risk — The market value of a convertible security performs like that of a regular debt security; that is, if market interest rates rise, the value of a convertible security usually falls. In addition, convertible securities are subject to the risk that the issuer will not be able to pay interest, principal or dividends when due, and their market value may change based on changes in the issuer’s credit rating or the market’s perception of the issuer’s creditworthiness. Since it derives a portion of its value from the common stock into which it may be converted, a convertible security is also subject to the same types of market and issuer risks that apply to the underlying common stock, including the potential for increased volatility in the price of the convertible security. |
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BlackRock Real Estate Securities Fund | Investment Style Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Investment Style Risk — Under certain market conditions, value investments have performed better during periods of economic recovery. Therefore, this investment style may over time go in and out of favor. At times when the investment style used by the Fund is out of favor, the Fund may underperform other equity funds that use different investment styles. |
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BlackRock Real Estate Securities Fund | Market Risk and Selection Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Market Risk and Selection Risk — Market risk is the risk that one or more markets in which the Fund invests will go down in value, including the possibility that the markets will go down sharply and unpredictably. The value of a security or other asset may decline due to changes in general market conditions, economic trends or events that are not specifically related to the issuer of the security or other asset, or factors that affect a particular issuer or issuers, exchange, country, group of countries, region, market, industry, group of industries, sector or asset class. Local, regional or global events such as war, acts of terrorism, the spread of infectious illness or other public health issues like pandemics or epidemics, recessions, or other events could have a significant impact on the Fund and its investments. Selection risk is the risk that the securities selected by Fund management will underperform the markets, the relevant indices or the securities selected by other funds with similar investment objectives and investment strategies. This means you may lose money. An outbreak of an infectious coronavirus (COVID-19) that was first detected in December 2019 developed into a global pandemic that has resulted in numerous disruptions in the market and has had significant economic impact leaving general concern and uncertainty. Although vaccines have been developed and approved for use by various governments, the duration of the pandemic and its effects cannot be predicted with certainty. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general ways that cannot necessarily be foreseen at the present time.
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BlackRock Real Estate Securities Fund | Preferred Securities Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Preferred Securities Risk — Preferred securities may pay fixed or adjustable rates of return. Preferred securities are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred securities of smaller companies may be more vulnerable to adverse developments than preferred securities of larger companies.
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BlackRock Real Estate Securities Fund | Risk of Investing in the United States [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Risk of Investing in the United States — Certain changes in the U.S. economy, such as when the U.S. economy weakens or when its financial markets decline, may have an adverse effect on the securities to which the Fund has exposure.. |
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BlackRock Real Estate Securities Fund | Small and Mid Capitalization Company Risk [Member] | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Risk [Text Block] | rr_RiskTextBlock | ◼ Small and Mid-Capitalization Company Risk — Companies with small or mid-size market capitalizations will normally have more limited product lines, markets and financial resources and will be dependent upon a more limited management group than larger capitalized companies. In addition, it is more difficult to get information on smaller companies, which tend to be less well known, have shorter operating histories, do not have significant ownership by large investors and are followed by relatively few securities analysts. |
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BlackRock Real Estate Securities Fund | Investor A Shares | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | 5.25% | ||||||||
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | [1] | |||||||
Management Fee | rr_ManagementFeesOverAssets | 0.75% | [2] | |||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 0.25% | ||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.24% | ||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.24% | ||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.24%) | [2],[3] | |||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.00% | [2],[3] | |||||||
1 Year | rr_ExpenseExampleYear01 | $ 622 | ||||||||
3 Years | rr_ExpenseExampleYear03 | 875 | ||||||||
5 Years | rr_ExpenseExampleYear05 | 1,148 | ||||||||
10 Years | rr_ExpenseExampleYear10 | $ 1,926 | ||||||||
2014 | rr_AnnualReturn2014 | 31.18% | ||||||||
2015 | rr_AnnualReturn2015 | 3.48% | ||||||||
2016 | rr_AnnualReturn2016 | 7.37% | ||||||||
2017 | rr_AnnualReturn2017 | 5.91% | ||||||||
2018 | rr_AnnualReturn2018 | (3.28%) | ||||||||
2019 | rr_AnnualReturn2019 | 27.53% | ||||||||
2020 | rr_AnnualReturn2020 | (4.43%) | ||||||||
2021 | rr_AnnualReturn2021 | 45.86% | ||||||||
2022 | rr_AnnualReturn2022 | (27.74%) | ||||||||
2023 | rr_AnnualReturn2023 | 13.29% | ||||||||
Year to Date Return, Label | rr_YearToDateReturnLabel | year-to-date return | ||||||||
Bar Chart, Year to Date Return, Date | rr_BarChartYearToDateReturnDate | Mar. 31, 2023 | ||||||||
Bar Chart, Year to Date Return | rr_BarChartYearToDateReturn | (1.77%) | ||||||||
Highest Quarterly Return, Label | rr_HighestQuarterlyReturnLabel | highest return | ||||||||
Highest Quarterly Return, Date | rr_BarChartHighestQuarterlyReturnDate | Dec. 31, 2023 | ||||||||
Highest Quarterly Return | rr_BarChartHighestQuarterlyReturn | 18.19% | ||||||||
Lowest Quarterly Return, Label | rr_LowestQuarterlyReturnLabel | lowest return | ||||||||
Lowest Quarterly Return, Date | rr_BarChartLowestQuarterlyReturnDate | Mar. 31, 2020 | ||||||||
Lowest Quarterly Return | rr_BarChartLowestQuarterlyReturn | (24.07%) | ||||||||
1 Year | rr_AverageAnnualReturnYear01 | 7.34% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 6.64% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 7.49% | ||||||||
BlackRock Real Estate Securities Fund | Investor C Shares | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | 1.00% | [4] | |||||||
Management Fee | rr_ManagementFeesOverAssets | 0.75% | [2] | |||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | 1.00% | ||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.38% | ||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 2.13% | ||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.38%) | [2],[3] | |||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 1.75% | [2],[3] | |||||||
1 Year | rr_ExpenseExampleYear01 | $ 278 | ||||||||
3 Years | rr_ExpenseExampleYear03 | 630 | ||||||||
5 Years | rr_ExpenseExampleYear05 | 1,109 | ||||||||
10 Years | rr_ExpenseExampleYear10 | 2,204 | ||||||||
1 Year | rr_ExpenseExampleNoRedemptionYear01 | 178 | ||||||||
3 Years | rr_ExpenseExampleNoRedemptionYear03 | 630 | ||||||||
5 Years | rr_ExpenseExampleNoRedemptionYear05 | 1,109 | ||||||||
10 Years | rr_ExpenseExampleNoRedemptionYear10 | $ 2,204 | ||||||||
1 Year | rr_AverageAnnualReturnYear01 | 11.43% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 6.96% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 7.42% | ||||||||
BlackRock Real Estate Securities Fund | Institutional Shares | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) | rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice | none | ||||||||
Maximum Deferred Sales Charge (Load) (as a percentage of offering price or redemption proceeds, whichever is lower) | rr_MaximumDeferredSalesChargeOverOfferingPrice | none | ||||||||
Management Fee | rr_ManagementFeesOverAssets | 0.75% | [2] | |||||||
Distribution and/or Service (12b-1) Fees | rr_DistributionAndService12b1FeesOverAssets | none | ||||||||
Other Expenses | rr_OtherExpensesOverAssets | 0.35% | ||||||||
Total Annual Fund Operating Expenses | rr_ExpensesOverAssets | 1.10% | ||||||||
Fee Waivers and/or Expense Reimbursements | rr_FeeWaiverOrReimbursementOverAssets | (0.35%) | [2],[3] | |||||||
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements | rr_NetExpensesOverAssets | 0.75% | [2],[3] | |||||||
1 Year | rr_ExpenseExampleYear01 | $ 77 | ||||||||
3 Years | rr_ExpenseExampleYear03 | 315 | ||||||||
5 Years | rr_ExpenseExampleYear05 | 572 | ||||||||
10 Years | rr_ExpenseExampleYear10 | $ 1,309 | ||||||||
1 Year | rr_AverageAnnualReturnYear01 | 13.59% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 8.04% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 8.34% | ||||||||
BlackRock Real Estate Securities Fund | Return After Taxes on Distributions | Investor A Shares | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
1 Year | rr_AverageAnnualReturnYear01 | 6.53% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 5.89% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 6.12% | ||||||||
BlackRock Real Estate Securities Fund | Return After Taxes on Distributions and Sale of Fund Shares | Investor A Shares | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
1 Year | rr_AverageAnnualReturnYear01 | 4.47% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 4.94% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 5.45% | ||||||||
BlackRock Real Estate Securities Fund | FTSE Nareit All Equity REITs Net Index (Reflects no deduction for fees, expenses or taxes) | ||||||||||
Risk/Return: | rr_RiskReturnAbstract | |||||||||
1 Year | rr_AverageAnnualReturnYear01 | 9.95% | ||||||||
5 Years | rr_AverageAnnualReturnYear05 | 6.41% | ||||||||
10 Years | rr_AverageAnnualReturnYear10 | 6.72% | ||||||||
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