The investment objective of BlackRock All-Cap Energy & Resources Portfolio ("All-Cap Energy & Resources" or the "Fund"), a series of BlackRock Funds^SM (the "Trust"), is to provide long-term growth of capital.

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 and hold Class R Shares of All-Cap Energy & Resources.

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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February 1, 2013

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 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 22% of the average value of its portfolio.

Portfolio Turnover, Rate

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22.00%

Other Expenses, New Fund, Based on Estimates [Text]

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Other Expenses are based on estimated amounts for the current fiscal year

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 conditions, All-Cap Energy & Resources invests at least 80% of its total assets in equity securities of global energy and natural resources companies and companies in associated businesses, as well as utilities (such as gas, water, cable, electrical and telecommunications utilities). Equity securities include common and preferred stock, convertible securities, warrants, depositary receipts and securities or other instruments whose price is linked to the price of common stock.

The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in energy or natural resources companies. The Fund may invest without limit in companies located anywhere in the world and will generally invest in at least three countries and in companies tied economically to a number of countries. The Fund expects to invest primarily in developed markets, but may also invest in emerging markets. The Fund may invest in companies of any size.

The Fund may, when consistent with the Fund's investment objective, buy or sell options or futures on a security or an index of securities and may buy options on a currency or a basket of currencies (commonly known as derivatives).

Strategy Portfolio Concentration [Text]

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The Fund will concentrate its investments (i.e., invest more than 25% of its assets) in energy or natural resources companies.

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 All-Cap Energy & Resources, 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 certain risks of investing in the Fund.

Commodities Market Risk — Stocks of companies engaged in commodities related industries are especially affected by variations in the commodities markets (that may be due to market events, regulatory developments or other factors that the Fund cannot control) and these companies may lack the resources and the broad business lines to weather hard times.

Concentration Risk — The Fund's strategy of concentrating in energy and natural resources companies 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.

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 that apply to the underlying common stock.

Depositary Receipts Risk — 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. Depositary receipts are generally subject to the same risks as the foreign securities that they evidence or into which they may be converted.

Derivatives Risk — The Fund's use of derivatives may reduce the Fund's returns and/or increase volatility. Volatility is defined as the characteristic of a security, an index or a market to fluctuate significantly in price within a short time period. Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will not fulfill its contractual obligation. A risk of the Fund's use of derivatives is that the fluctuations in their values may not correlate perfectly with the overall securities markets. 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. Derivatives may give rise to a form of leverage and may expose the Fund to greater risk and increase its costs. Recent legislation calls for new regulation of the derivatives markets. The extent and impact of the regulation is not yet known and may not be known for some time. New regulation may make derivatives more costly, may limit the availability of derivatives, or may otherwise adversely affect the value or performance of derivatives.

Emerging Markets Risk — Emerging markets are riskier than more developed markets because they tend to develop unevenly and may never fully develop. Investments in emerging markets may be considered speculative. Emerging markets are more likely to experience hyperinflation and currency devaluations, which adversely affect returns to U.S. investors. In addition, many emerging securities markets have far lower trading volumes and less liquidity than developed markets.

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:

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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.

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Changes in foreign currency exchange rates can affect the value of the Fund's portfolio.

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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.

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The governments of certain countries may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries.

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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.

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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.

Geographic Concentration Risk — From time to time the Fund may invest a substantial amount of its assets in issuers located in a single country or a limited number of countries. If the Fund concentrates its investments in this manner, it assumes the risk that economic, political and social conditions in those countries will have a significant impact on its investment performance. The Fund's investment performance may also be more volatile if it concentrates its investments in certain countries, especially emerging market countries.

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.

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.

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.

Small Cap Securities Risk — Small cap companies may have limited product lines or markets. They may be less financially secure than larger, more established companies. They may depend on a more limited management group than larger capitalized companies.

Warrants Risk — If the price of the underlying stock does not rise above the exercise price before the warrant expires, the warrant generally expires without any value and the Fund loses any amount it paid for the warrant. Thus, investments in warrants may involve substantially more risk than investments in common stock. Warrants may trade in the same markets as their underlying stock; however, the price of the warrant does not necessarily move with the price of the underlying stock.

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.

Risk Nondiversified Status [Text]

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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]

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Performance Information

Performance Narrative [Text Block]

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Class R Shares do not have a performance history as of the date of this prospectus. As a result, the chart and table give you a picture of the long-term performance of All-Cap Energy & Resources for Investor A Shares, which are not offered in this prospectus. Investor A Shares would have annual returns substantially similar to Class R Shares differing only to the extent that Investor A and Class R Shares have different expenses. The actual return of Class R Shares would generally be lower than that of Investor A Shares because Class R Shares are subject to higher distribution and/or service (12b-1) fees than Investor A Shares.

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 Standard & Poor's ("S&P") 500^® Index and a customized weighted index comprised of 70% Wilshire 5000 Modified Energy Cap Weighted Index and 30% MSCI All-Country World Energy Index, which are relevant to the Fund because they have characteristics similar to the Fund's investment strategies. 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 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]

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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]

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(800) 882-0052

Performance Availability Website Address [Text]

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http://www.blackrock.com/funds

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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Investor A Shares
ANNUAL TOTAL RETURNS
BlackRock All-Cap Energy & Resources Portfolio
As of 12/31

Bar Chart Does Not Reflect Sales Loads [Text]

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Sales charges are not reflected in the bar chart. If they were, returns would be less than those shown.

Bar Chart Closing [Text Block]

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During the period shown in the bar chart, the highest return for a quarter was 28.89% (quarter ended June 30, 2008) and the lowest return for a quarter was –39.62% (quarter ended December 31, 2008).

Performance Table Heading

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As of 12/31/11
Average Annual Total Returns

Performance Table Does Reflect Sales Loads

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However, the table includes all applicable fees and sales charges.

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 One Class of after Tax Shown [Text]

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After-tax returns are shown for Investor A Shares only, and the after-tax returns for Class R Shares will vary.

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. After-tax returns are shown for Investor A Shares only, and the after-tax returns for Class R Shares will vary.

BLACKROCK ALL-CAP ENERGY & RESOURCES PORTFOLIO | S&P 500 Index (Reflects no deduction for fees, expenses or taxes)

Risk/Return:

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1 Year

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2.11%

5 Years

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(0.25%)

Since Inception

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2.67%

BLACKROCK ALL-CAP ENERGY & RESOURCES PORTFOLIO | 70% Wilshire 5000 Modified Energy Cap Weighted Index/30% MSCI All-Country World Energy Index (Reflects no deduction for fees, expenses or taxes)

Risk/Return:

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1 Year

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(1.22%)

5 Years

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4.90%

Since Inception

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9.93%

[1]

Other Expenses are based on estimated amounts for the current fiscal year.

[2]

As described in the "Management of the Funds" section of the Fund's prospectus on pages 55-63, BlackRock Advisors, LLC ("BlackRock") has contractually agreed to waive and/or reimburse fees 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 1.83% of average daily net assets until February 1, 2013. 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.