Objective, Primary [Text Block]

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Risk/Return [Heading]

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Fund Overview Key Facts about BlackRock Global Long/Short Equity Fund

Objective [Heading]

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Investment Objective

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The investment objective of BlackRock Global Long/Short Equity Fund (the “Fund”), a series of BlackRock Funds^SM (the “Trust”), is to seek total return over the long term.

Expense [Heading]

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Fees and Expenses of the Fund

Expense Narrative [Text Block]

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This table describes the fees and expenses that you may pay if you buy, hold and sell Class K 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.

Operating Expenses Caption [Text]

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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

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June 30, 2023

Portfolio Turnover [Heading]

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Portfolio Turnover:

Portfolio Turnover [Text Block]

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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 43% of the average value of its portfolio.

Portfolio Turnover, Rate

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43.00%

Expenses Restated to Reflect Current [Text]

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The Management Fee has been restated to reflect current fees.

Expense Example [Heading]

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Example:

Expense Example Narrative [Text Block]

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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:

Strategy [Heading]

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Principal Investment Strategies of the Fund

Strategy Narrative [Text Block]

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Under normal circumstances, the Fund invests at least 80% of its total assets in equity instruments and related derivative instruments issued by, or tied economically to, companies located in developed markets. The Fund determines that an investment is tied economically to a developed market if such investment satisfies one or more of the following conditions: 1) the issuer’s primary trading market is in a developed market; 2) the issuer is organized under the laws of, derives at least 50% of its revenue from, or has at least 50% of its assets in developed markets; 3) the investment is included in an index representative of developed markets; and 4) the investment is exposed to the economic risks and returns of developed markets. The Fund may invest in securities of issuers of any market capitalization and in securities denominated in either U.S. dollars or foreign currencies.

The Fund pursues its investment objective by taking both long and short positions in a variety of developed market equity instruments. The Fund expects to maintain long and short positions primarily through the use of swap agreements and other derivative instruments, such as futures, and may invest in such instruments without limitation. Although the Fund intends to maintain an overall long position in its portfolio investments, the Fund generally expects to maintain significant short positions in equity securities and equity-related instruments. In certain circumstances, these short positions may approach or reach the size of the overall long position. The use of both long and short positions better enables the Fund to seek to produce returns that have low correlation to those available by investing in the market as a whole. A long position arises where the Fund holds a security in its portfolio or maintains a position through a derivative instrument that provides economic exposure similar to direct ownership of the security. The Fund will have a short position where it sells a security it does not own by delivery of a borrowed security or has entered into a derivative instrument that provides economic exposure similar to a short sale of the security. The Fund looks to identify overvalued, undervalued or mispriced stocks and other equity instruments through proprietary ranking techniques. The Fund takes long positions primarily in securities that BlackRock has identified as attractive and short positions in such securities that BlackRock has identified as overvalued or poised for underperformance.

Under normal circumstances, the Fund anticipates it will allocate a substantial amount (approximately 40% or more — unless market conditions are not deemed favorable by BlackRock, in which case the Fund would invest at least 30%) of its total assets in securities (or derivatives with similar economic characteristics) of (i) foreign government issuers, (ii) issuers organized or located outside the United States, (iii) issuers whose securities primarily trade in a market located outside the United States, or (iv) issuers doing a substantial amount of business outside the United States, which the Fund considers to be companies that derive at least 50% of their revenue or profits from business outside the United States or have at least 50% of their sales or assets outside the United States. The Fund will allocate its assets among various regions and countries, including the United States (but in no less than three different countries). For temporary defensive purposes, the Fund may deviate very substantially from the allocation described above.

The Fund may utilize derivative instruments as a significant part of its strategy.

When consistent with the Fund’s investment objective, the Fund’s investments may include short-term investments, such as cash and cash equivalents, U.S. Government and agency securities, money market funds (including funds that may be affiliated with or sponsored or managed by BlackRock), commercial paper, certificates of deposit and other bank deposits and bankers’ acceptances.

Equity instruments consist of:

■	Common stock
■	Depositary receipts
■	Derivative securities or instruments such as futures, options, forward contracts and swaps (including, but not limited to, total return swaps, some of which may be referred to as contracts for difference), the value of which is based on a common stock or group of common stocks. A contract for difference offers exposure to price changes in an underlying security without ownership of such security, typically by providing investors the ability to trade on margin.

The Fund may engage in active and frequent trading of portfolio securities to achieve its primary investment strategies.

Risk [Heading]

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Principal Risks of Investing in the Fund

Risk Narrative [Text Block]

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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 the principal risks of investing in the Fund. The order of the below risk factors does not indicate the significance of any particular risk factor.

■	Depositary Receipts Risk — Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted. In addition to investment risks associated with the underlying issuer, depositary receipts expose the Fund to additional risks associated with the non-uniform terms that apply to depositary receipt programs, credit exposure to the depository bank and to the sponsors and other parties with whom the depository bank establishes the programs, currency risk and the risk of an illiquid market for depositary receipts. The issuers of unsponsored depositary receipts are not obligated to disclose information that is, in the United States, considered material. Therefore, there may be less information available regarding these issuers and there may not be a correlation between such information and the market value of the depositary receipts.
■	Derivatives Risk — The Fund’s use of derivatives may increase its costs, reduce the Fund’s returns and/or increase volatility. Derivatives involve significant risks, including:
	Volatility Risk — Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. A risk of the Fund’s use of derivatives is that the fluctuations in their values may not correlate with the overall securities markets.
	Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation.
	Market and Illiquidity Risk — The possible lack of a liquid secondary market for derivatives and the resulting inability of the Fund to sell or otherwise close a derivatives position could expose the Fund to losses and could make derivatives more difficult for the Fund to value accurately.
	Valuation Risk — Valuation may be more difficult in times of market turmoil since many investors and market makers may be reluctant to purchase complex instruments or quote prices for them.
	Hedging Risk — Hedges are sometimes subject to imperfect matching between the derivative and the underlying security, and there can be no assurance that the Fund’s hedging transactions will be effective. The use of hedging may result in certain adverse tax consequences.
	Tax Risk — Certain aspects of the tax treatment of derivative instruments, including swap agreements and commodity-linked derivative instruments, are currently unclear and may be affected by changes in legislation, regulations or other legally binding authority. Such treatment may be less favorable than that given to a direct investment in an underlying asset and may adversely affect the timing, character and amount of income the Fund realizes from its investments.
	Regulatory Risk — Derivative contracts, including, without limitation, swaps, currency forwards and non-deliverable forwards, are subject to regulation under the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Dodd-Frank Act”) in the United States and under comparable regimes in Europe, Asia and other non-U.S. jurisdictions. Under the Dodd-Frank Act, certain derivatives are subject to margin requirements and swap dealers are required to collect margin from the Fund with respect to such derivatives. Specifically, regulations are now in effect that require swap dealers to post and collect variation margin (comprised of specified liquid instruments and subject to a required haircut) in connection with trading of over-the-counter (“OTC”) swaps with the Fund. Shares of investment companies (other than certain money market funds) may not be posted as collateral under these regulations. Requirements for posting of initial margin in connection with OTC swaps will be phased-in through at least 2021. In addition, regulations adopted by global prudential regulators that are now in effect require certain bank-regulated counterparties and certain of their affiliates to include in certain financial contracts, including many derivatives contracts, terms that delay or restrict the rights of counterparties, such as the Fund, to terminate such contracts, foreclose upon collateral, exercise other default rights or restrict transfers of credit support in the event that the counterparty and/or its affiliates are subject to certain types of resolution or insolvency proceedings. The implementation of these requirements with respect to derivatives, as well as regulations under the Dodd-Frank Act regarding clearing, mandatory trading and margining of other derivatives, may increase the costs and risks to the Fund of trading in these instruments and, as a result, may affect returns to investors in the Fund.
	On October 28, 2020, the Securities and Exchange Commission (the “SEC”) adopted new regulations governing the use of derivatives by registered investment companies (“Rule 18f-4”). The Fund will be required to implement and comply with Rule 18f-4 by August 19, 2022. Once implemented, Rule 18f-4 will impose limits on the amount of

derivatives a fund can enter into, eliminate the asset segregation framework currently used by funds to comply with Section 18 of the Investment Company Act of 1940, as amended, treat derivatives as senior securities and require funds whose use of derivatives is more than a limited specified exposure amount to establish and maintain a comprehensive derivatives risk management program and appoint a derivatives risk manager.

Risks Specific to Certain Derivatives Used by the Fund

Forward Foreign Currency Exchange Contracts— Forward foreign currency exchange transactions are OTC contracts to purchase or sell a specified amount of a specified currency or multinational currency unit at a price and future date set at the time of the contract. Forward foreign currency exchange contracts do not eliminate fluctuations in the value of non-U.S. securities but rather allow the Fund to establish a fixed rate of exchange for a future point in time. This strategy can have the effect of reducing returns and minimizing opportunities for gain.

Futures — Futures are standardized, exchange-traded contracts that obligate a purchaser to take delivery, and a seller to make delivery, of a specific amount of an asset at a specified future date at a specified price. The primary risks associated with the use of futures contracts and options are: (a) the imperfect correlation between the change in market value of the instruments held by the Fund and the price of the futures contract or option; (b) the possible lack of a liquid secondary market for a futures contract and the resulting inability to close a futures contract when desired; (c) losses caused by unanticipated market movements, which are potentially unlimited; (d) the investment adviser’s inability to predict correctly the direction of securities prices, interest rates, currency exchange rates and other economic factors; and (e) the possibility that the counterparty will default in the performance of its obligations.

Swaps — Swap agreements, including total return swaps that may be referred to as contracts for difference, are two-party contracts entered into for periods ranging from a few weeks to more than one year. In a standard “swap” transaction, two parties agree to exchange the returns (or differentials in rates of return) earned or realized on particular predetermined investments or instruments, which can be adjusted for an interest factor. Swap agreements involve the risk that the party with whom the Fund has entered into the swap will default on its obligation to pay the Fund and the risk that the Fund will not be able to meet its obligations to pay the other party to the agreement. Swap agreements may also involve the risk that there is an imperfect correlation between the return on the Fund’s obligation to its counterparty and the return on the referenced asset. In addition, swap agreements are subject to market and illiquidity risk, leverage risk and hedging risk. The income tax treatment of swap agreements is unsettled and may be subject to future legislation, regulation or administrative pronouncements issued by the Internal Revenue Service. If future guidance limits the Fund’s ability to use derivatives, the Fund may have to find other ways of achieving its investment objective. The Fund expects to settle or close out swap positions from time to time so that the value of any “in-the-money” swap positions with a single counterparty (and other securities issued by that counterparty) will not exceed 5% of the value of the Fund’s total assets. While this is intended to limit counterparty risk, it is also likely to result in the Fund realizing and distributing to its shareholders more ordinary income and less long-term capital gains, which may be taxable at more favorable rates than ordinary income.

To the extent derivatives are utilized to implement the Fund’s investment strategies, the transactions may involve the risks described below with respect to investments in equity securities and short sales of securities.

■	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.
■	Foreign Securities Risk — Foreign investments often involve special risks not present in U.S. investments that can increase the chances that the Fund will lose money. These risks include:

■	The Fund generally holds its foreign securities and cash in foreign banks and securities depositories, which may be recently organized or new to the foreign custody business and may be subject to only limited or no regulatory oversight.
■	Changes in foreign currency exchange rates can affect the value of the Fund’s portfolio.
■	The economies of certain foreign markets may not compare favorably with the economy of the United States with respect to such issues as growth of gross national product, reinvestment of capital, resources and balance of payments position.
■	The governments of certain countries, or the U.S. Government with respect to certain countries, may prohibit or impose substantial restrictions through capital controls and/or sanctions on foreign investments in the capital markets or certain industries in those countries, which may prohibit or restrict the ability to own or transfer currency, securities, derivatives or other assets.

■	Many foreign governments do not supervise and regulate stock exchanges, brokers and the sale of securities to the same extent as does the United States and may not have laws to protect investors that are comparable to U.S. securities laws.
■	Settlement and clearance procedures in certain foreign markets may result in delays in payment for or delivery of securities not typically associated with settlement and clearance of U.S. investments.
■	The Fund’s claims to recover foreign withholding taxes may not be successful, and if the likelihood of recovery of foreign withholding taxes materially decreases, due to, for example, a change in tax regulation or approach in the foreign country, accruals in the Fund’s net asset value for such refunds may be written down partially or in full, which will adversely affect the Fund’s net asset value.
■	The European financial markets have recently experienced volatility and adverse trends due to concerns about economic downturns in, or rising government debt levels of, several European countries. These events may spread to other countries in Europe. These events may affect the value and liquidity of certain of the Fund’s investments.

■	High Portfolio Turnover Risk — The Fund may engage in active and frequent trading of its portfolio securities. High portfolio turnover (more than 100%) may result in increased transaction costs to the Fund, including brokerage commissions, dealer mark-ups and other transaction costs on the sale of the securities and on reinvestment in other securities. The sale of Fund portfolio securities may result in the realization and/or distribution to shareholders of higher capital gains or losses as compared to a fund with less active trading policies. These effects of higher than normal portfolio turnover may adversely affect Fund performance.
■	Indexed Securities Risk — Indexed securities provide a potential return based on a particular index of value or interest rates. The Fund’s return on these securities will be subject to risk with respect to the value of the particular index. These securities are subject to leverage risk and correlation risk. Certain indexed securities have greater sensitivity to changes in interest rates or index levels than other securities, and the Fund’s investment in such instruments may decline significantly in value if interest rates or index levels move in a way Fund management does not anticipate.
■	Leverage Risk — Some transactions may give rise to a form of economic leverage. These transactions may include, among others, derivatives, and may expose the Fund to greater risk and increase its costs. The use of leverage may cause the Fund to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet any required asset segregation requirements. Increases and decreases in the value of the Fund’s portfolio will be magnified when the Fund uses leverage.
■	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. The Fund seeks to pursue its investment objective by using proprietary models that incorporate quantitative analysis and is subject to “Model Risk” as described below. This means you may lose money.
	A recent outbreak of an infectious coronavirus has 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. 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.
■	Mid Cap Securities Risk — The securities of mid cap companies generally trade in lower volumes and are generally subject to greater and less predictable price changes than the securities of larger capitalization companies.
■	Model Risk — The Fund seeks to pursue its investment objective by using proprietary models that incorporate quantitative analysis. Investments selected using these models may perform differently than as forecasted due to the factors incorporated into the models and the weighting of each factor, changes from historical trends, and issues in the construction and implementation of the models (including, but not limited to, software issues and other technological issues). There is no guarantee that BlackRock’s use of these models will result in effective investment decisions for the Fund.

	The information and data used in the models may be supplied by third parties. Inaccurate or incomplete data may limit the effectiveness of the models. In addition, some of the data that BlackRock uses may be historical data, which may not accurately predict future market movement. There is a risk that the models will not be successful in selecting investments or in determining the weighting of investment positions that will enable the Fund to achieve its investment objective.
■	Money Market Securities Risk — If market conditions improve while the Fund has invested some or all of its assets in high quality money market securities, this strategy could result in reducing the potential gain from the market upswing, thus reducing the Fund’s opportunity to achieve its investment objective.
■	Short Sales Risk — Because making short sales in securities that it does not own exposes the Fund to the risks associated with those securities, such short sales involve speculative exposure risk. The Fund will incur a loss as a result of a short sale if the price of the security increases between the date of the short sale and the date on which the Fund replaces the security sold short. Short sale transactions involve leverage because they can provide investment exposure in an amount exceeding the initial investment.
■	Treasury Obligations Risk — Direct obligations of the U.S. Treasury have historically involved little risk of loss of principal if held to maturity. However, due to fluctuations in interest rates, the market value of such securities may vary during the period shareholders own shares of the Fund.

Risk Lose Money [Text]

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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]

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Performance Information

Performance Narrative [Text Block]

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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. Class K Shares commenced operations on March 28, 2016. As a result, the returns shown below for Class K Shares prior to March 28, 2016 are those of the Fund’s Institutional Shares, which are not offered in this prospectus. The performance of Class K Shares would be substantially similar to Institutional Shares because Class K Shares and Institutional Shares are invested in the same portfolio of securities and performance would differ only to the extent that Class K Shares and Institutional Shares have different expenses. The actual returns of Class K Shares would have been higher than those of Institutional Shares because Class K Shares have lower expenses than Institutional Shares. The table compares the Fund’s performance to that of the ICE BofA 3-Month U.S. Treasury Bill 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. The table includes all applicable fees. 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 http://www.blackrock.com or can be obtained by phone at (800) 882-0052.

Performance Information Illustrates Variability of Returns [Text]

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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]

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(800) 882-0052

Performance Availability Website Address [Text]

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http://www.blackrock.com

Performance Past Does Not Indicate Future [Text]

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As with all such investments, past performance (before and after taxes) is not an indication of future results.

Bar Chart [Heading]

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Class K Shares ANNUAL TOTAL RETURNS BlackRock Global Long/Short Equity Fund As of 12/31

Bar Chart Closing [Text Block]

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During the periods shown in the bar chart, the highest return for a quarter was 6.06% (quarter ended June 30, 2020) and the lowest return for a quarter was -4.90% (quarter ended June 30, 2016). The year-to-date return as of June 30, 2021 was 4.90%.

Performance Table Heading

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For the periods ended 12/31/20 Average Annual Total Returns

Performance Table Uses Highest Federal Rate

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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

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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 Narrative

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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.

Class K | BlackRock Global Long/Short Equity Fund | Class K Shares

Distribution and/or Service (12b-1) Fees

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Management Fee

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1.25%

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none

Other Expenses

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0.27%

Total Annual Fund Operating Expenses

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1.52%

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Fee Waivers and/or Expense Reimbursements

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(0.23%)

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Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements

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1.29%

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rr_ExpenseExampleYear01

$ 131

3 Years

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458

Year to Date Return, Label

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807

10 Years

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$ 1,793

2013

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18.76%

2014

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1.13%

2015

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(0.98%)

2016

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(6.77%)

2017

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12.93%

2018

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2.21%

2019

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(0.81%)

2020

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0.33%

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year-to-date return

Bar Chart, Year to Date Return, Date

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Jun. 30, 2021

Bar Chart, Year to Date Return

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4.90%

Highest Quarterly Return, Label

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highest return

Highest Quarterly Return, Date

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Jun. 30, 2020

Highest Quarterly Return

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6.06%

Lowest Quarterly Return, Label

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lowest return

Lowest Quarterly Return, Date

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Jun. 30, 2016

Lowest Quarterly Return

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(4.90%)

rr_AverageAnnualReturnYear01

0.33%

rr_AverageAnnualReturnYear05

1.38%

Class K | BlackRock Global Long/Short Equity Fund | Return After Taxes on Distributions | Class K Shares

rr_AverageAnnualReturnSinceInception

3.07%

Inception Date

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Dec. 20, 2012

rr_RiskReturnAbstract

rr_AverageAnnualReturnYear01

0.20%

rr_AverageAnnualReturnYear05

0.76%

Class K | BlackRock Global Long/Short Equity Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class K Shares

rr_AverageAnnualReturnSinceInception

2.54%

Inception Date

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Dec. 20, 2012

rr_RiskReturnAbstract

rr_AverageAnnualReturnYear01

0.20%

rr_AverageAnnualReturnYear05

0.81%

Class K | BlackRock Global Long/Short Equity Fund | ICE BofA 3-Month U.S. Treasury Bill Index (Reflects no deduction for fees, expenses or taxes)

rr_AverageAnnualReturnSinceInception

2.18%

Inception Date

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Dec. 20, 2012

rr_RiskReturnAbstract

rr_AverageAnnualReturnYear01

0.67%

rr_AverageAnnualReturnYear05

1.20%