Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	May 29, 2015
BlackRock Real Estate Securities Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview
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.
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 $25,000 in the fund complex advised by BlackRock Advisors, LLC (“BlackRock”) or its affiliates. More information about these and other discounts is available from your financial professional or your selected securities dealer, broker, investment adviser, service provider or industry professional (including BlackRock, The PNC Financial Services Group, Inc. and their respective affiliates) (each a “Financial Intermediary”) 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-61 of Part II of the Fund’s Statement of Additional Information.
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 1, 2016
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. For the fiscal year ended January 31, 2015, the Fund’s portfolio turnover rate was 74% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	74.00%
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 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 Advisors, LLC (“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:
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.
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
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. 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. 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 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 as apply to the underlying common stock. 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. 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. 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. 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. 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, 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 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. 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 are also subject to the possibilities of failing to qualify for tax free pass-through of income and failing to maintain their exemptions from investment company registration. 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.
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.
Risk Nondiversified Status [Text]	rr_RiskNondiversifiedStatus	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.
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 for the periods since inception and provides some indication of the risks of investing in the Fund. The table compares the Fund’s performance to that of the FTSE EPRA/NAREIT United States 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/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 for the periods since inception 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/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	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 period shown in the bar chart, the highest return for a quarter was 15.24% (quarter ended December 31, 2014) and the lowest return for a quarter was -3.38% (quarter ended September 30, 2014). The year-to-date return as of March 31, 2015 was 5.29%.
Performance Table Heading	rr_PerformanceTableHeading	As of 12/31/14 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.
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 original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none	[1]
Management Fee	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	0.25%
Other Expenses	rr_OtherExpensesOverAssets	0.88%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.88%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.58%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.30%	[2]
1 Year	rr_ExpenseExampleYear01	650
3 Years	rr_ExpenseExampleYear03	1,032
5 Years	rr_ExpenseExampleYear05	1,437
10 Years	rr_ExpenseExampleYear10	2,566
2013	rr_AnnualReturn2013	2.43%
2014	rr_AnnualReturn2014	31.18%
Year to Date Return, Label	rr_YearToDateReturnLabel	year-to-date return
Bar Chart, Year to Date Return, Date	rr_BarChartYearToDateReturnDate	Mar. 31, 2015
Bar Chart, Year to Date Return	rr_BarChartYearToDateReturn	5.29%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Dec. 31, 2014
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	15.24%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Sep. 30, 2014
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	(3.38%)
1 Year	rr_AverageAnnualReturnYear01	24.29%
Since Inception	rr_AverageAnnualReturnSinceInception	12.24%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 28, 2012
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 original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	1.00%	[3]
Management Fee	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	1.00%
Other Expenses	rr_OtherExpensesOverAssets	0.95%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	2.70%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.65%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	2.05%	[2]
1 Year	rr_ExpenseExampleYear01	308
3 Years	rr_ExpenseExampleYear03	777
5 Years	rr_ExpenseExampleYear05	1,372
10 Years	rr_ExpenseExampleYear10	2,984
1 Year	rr_ExpenseExampleNoRedemptionYear01	208
3 Years	rr_ExpenseExampleNoRedemptionYear03	777
5 Years	rr_ExpenseExampleNoRedemptionYear05	1,372
10 Years	rr_ExpenseExampleNoRedemptionYear10	2,984
1 Year	rr_AverageAnnualReturnYear01	29.16%
Since Inception	rr_AverageAnnualReturnSinceInception	14.11%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 28, 2012
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 original purchase price or redemption proceeds, whichever is lower)	rr_MaximumDeferredSalesChargeOverOfferingPrice	none
Management Fee	rr_ManagementFeesOverAssets	0.75%
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.92%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.67%
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.62%)	[2]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	1.05%	[2]
1 Year	rr_ExpenseExampleYear01	107
3 Years	rr_ExpenseExampleYear03	466
5 Years	rr_ExpenseExampleYear05	849
10 Years	rr_ExpenseExampleYear10	1,924
1 Year	rr_AverageAnnualReturnYear01	31.50%
Since Inception	rr_AverageAnnualReturnSinceInception	15.25%
Inception Date	rr_AverageAnnualReturnInceptionDate	Sep. 28, 2012
BlackRock Real Estate Securities Fund | Return After Taxes on Distributions | Investor A Shares
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	23.32%
Since Inception	rr_AverageAnnualReturnSinceInception	10.95%
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	13.85%
Since Inception	rr_AverageAnnualReturnSinceInception	8.84%
BlackRock Real Estate Securities Fund | FTSE EPRA/NAREIT United States Index (Reflects no deduction for fees, expenses or taxes)
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	30.43%
Since Inception	rr_AverageAnnualReturnSinceInception	15.00%

[1] 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 time of purchase as part of an investment of $1,000,000 or more.

[2] As described in the "Management of the Fund" section of the Fund's prospectus beginning on page 30, BlackRock has contractually agreed to waive and/or reimburse fees and/or expenses in order to limit Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements (excluding Dividend Expense, Interest Expense, Acquired Fund Fees and Expenses and certain other Fund expenses) to 1.30% of average daily net assets (for Investor A Shares), 2.05% of average daily net assets (for Investor C Shares) and 1.05% of average daily net assets (for Institutional Shares) until June 1, 2016. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The agreement may be terminated upon 90 days' notice by a majority of the non-interested trustees of the Trust or by a vote of a majority of the outstanding voting securities of the Fund.

[3] There is no CDSC on Investor C Shares after one year.