Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	BLACKROCK FUNDS
Prospectus Date	rr_ProspectusDate	Nov. 28, 2016
Institutional | BlackRock MSCI Asia ex Japan Index Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Fund Overview Key Facts About BlackRock MSCI Asia ex Japan Index Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The investment objective of BlackRock MSCI Asia ex Japan Index Fund (the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek to track the investment results of an index composed of Asian equities, excluding Japan.
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 Institutional Shares of the Fund.
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	November 30, 2017
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 11% of the average value of its portfolio.
Portfolio Turnover, Rate	rr_PortfolioTurnoverRate	11.00%
Expenses Restated to Reflect Current [Text]	rr_ExpensesRestatedToReflectCurrent	Other Expenses have been restated to reflect current fees.
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:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Strategies of the Fund
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund seeks to track the investment results of the MSCI AC Asia ex Japan Index (the “Underlying Index”), which is a free float-adjusted market capitalization index designed to measure equity market performance of the following 10 developed and emerging market countries or regions: China, Hong Kong, India, Indonesia, Korea, Malaysia, the Philippines, Singapore, Taiwan and Thailand. The Underlying Index includes equity securities issued by issuers which range in size between approximately $437 million and $149.8 billion, although this range may change from time to time. The Underlying Index may include large- or mid- capitalization companies, and components primarily include financial services, information technology and consumer discretionary companies. The components of the Underlying Index, and the degree to which these components represent certain industries, may change over time. BlackRock uses a representative sampling indexing strategy to manage the Fund. “Representative sampling” is an indexing strategy that involves investing in a representative sample of securities that collectively has an investment profile similar to that of the Underlying Index. The securities selected are expected to have, in the aggregate, investment characteristics (based on factors such as market capitalization and industry weightings), fundamental characteristics (such as return variability and yield) and liquidity measures similar to those of the Underlying Index. The Fund may or may not hold all of the securities in the Underlying Index. The Fund generally invests at least 90% of its assets, plus the amount of any borrowing for investment purposes, in securities of the Underlying Index and in depositary receipts representing securities of the Underlying Index.
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 the principal risks of investing in the Fund. Asset Class Risk — Securities and other assets in the Underlying Index or in the Fund’s portfolio may underperform in comparison to the general financial markets, a particular financial market or other asset classes. Concentration Risk — The Fund reserves the right to concentrate its investments (i.e., invest 25% or more of its total assets in securities of issuers in a particular industry) to approximately the same extent that the Underlying Index concentrates in a particular industry. To the extent the Fund concentrates in a particular industry, it may be more susceptible to economic conditions and risks affecting that industry. Consumer Discretionary Sector Risk — The consumer discretionary sector may be affected by changes in domestic and international economies, exchange and interest rates, competition, consumers’ disposable income, consumer preferences, social trends and marketing campaigns. 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. 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. Financials Sector Risk — Performance of companies in the financials sector may be adversely impacted by many factors, including, among others, government regulations, economic conditions, credit rating downgrades, changes in interest rates, and decreased liquidity in credit markets. The impact of more stringent capital requirements, recent or future regulation of any individual financial company, or recent or future regulation of the financials sector as a whole cannot be predicted. In recent years, cyber attacks and technology malfunctions have become increasingly frequent in this sector and have caused significant losses to companies in this sector, which may negatively impact the Fund. 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 may prohibit or impose substantial restrictions on foreign investments in their capital markets or in certain industries. 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. 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. Index Fund Risk — An index fund has operating and other expenses while an index does not. As a result, while the Fund will attempt to track the Underlying Index as closely as possible, it will tend to underperform the Underlying Index to some degree over time. If an index fund is properly correlated to its stated index, the fund will perform poorly when the index performs poorly. Index-Related Risk — There is no guarantee that the Fund will achieve a high degree of correlation to the Underlying Index and therefore achieve its investment objective. Market disruptions and regulatory restrictions could have an adverse effect on the Fund’s ability to adjust its exposure to the required levels in order to track the Underlying Index. Errors in index data, index computations and/or the construction of the Underlying Index in accordance with its methodology may occur from time to time and may not be identified and corrected by the index provider for a period of time or at all, which may have an adverse impact on the Fund and its shareholders. Information Technology Sector Risk — Information technology companies face intense competition and potentially rapid product obsolescence. They are also heavily dependent on intellectual property rights and may be adversely affected by the loss or impairment of those rights. Investment in a Particular Geographic Region or Country Risk — Asia-Pacific Countries — In addition to the risks of investing in non-U.S. securities and the risks of investing in emerging markets, the developing market Asia-Pacific countries are subject to certain additional or specific risks. In many of these markets, there is a high concentration of market capitalization and trading volume in a small number of issuers representing a limited number of industries, as well as a high concentration of investors and financial intermediaries. Many of these markets also may be affected by developments with respect to more established markets in the region such as Hong Kong. Brokers in developing market Asia-Pacific countries typically are fewer in number and less well capitalized than brokers in the United States. Many of the developing market Asia-Pacific countries may be subject to a greater degree of economic, political and social instability than is the case in the United States and Western European countries. Such instability may result from, among other things: (i) authoritarian governments or military involvement in political and economic decision-making, including changes in government through extra-constitutional means; (ii) popular unrest associated with demands for improved political, economic and social conditions; (iii) internal insurgencies; (iv) hostile relations with neighboring countries; and (v) ethnic, religious and racial disaffection. In addition, the governments of many of such countries, such as Indonesia, have a substantial role in regulating and supervising the economy. Another risk common to most such countries is that the economy is heavily export oriented and, accordingly, is dependent upon international trade. The existence of overburdened infrastructure and obsolete financial systems also presents risks in certain countries, as do environmental problems. Certain economies also depend to a significant degree upon exports of primary commodities and, therefore, are vulnerable to changes in commodity prices that, in turn, may be affected by a variety of factors. The rights of investors in developing market Asia-Pacific companies may be more limited than those of shareholders of U.S. corporations. It may be difficult or impossible to obtain and/or enforce a judgment in a developing market Asia-Pacific country. Some developing Asia-Pacific countries prohibit or impose substantial restrictions on investments in their capital markets, particularly their equity markets, by foreign entities. For example, certain countries may require governmental approval prior to investments by foreign persons or limit the amount of investment by foreign persons in a particular company. Risks of Investing in China — Investments in Chinese issuers subject the Fund to risks specific to China. China may be subject to considerable degrees of economic, political and social instability. China is a developing market and demonstrates significantly higher volatility from time to time in comparison to developed markets. Over the past 25 years, the Chinese government has undertaken reform of economic and market practices and is expanding the sphere of private ownership of property in China. However, Chinese markets generally continue to experience inefficiency, volatility and pricing anomalies resulting from governmental influence, a lack of publicly available information and/or political and social instability. Internal social unrest or confrontations with other neighboring countries, including military conflicts in response to such events, may also disrupt economic development in China and result in a greater risk of currency fluctuations, currency convertibility, interest rate fluctuations and higher rates of inflation. Export growth continues to be a major driver of China’s rapid economic growth. Reduction in spending on Chinese products and services, institution of tariffs or other trade barriers, or a downturn in any of the economies of China’s key trading partners may have an adverse impact on the Chinese economy. Risks of Investing in India — Investments in Indian issuers involve risks that are specific to India, including legal, regulatory, political and economic risks. Political and legal uncertainty, greater government control over the economy, currency fluctuations or blockage and the risk of nationalization or expropriation of assets may result in higher potential for losses. The securities markets in India are relatively underdeveloped and may subject the Fund to higher transaction costs or greater uncertainty than investments in more developed securities markets. Risks of Investing in South Korea — Investments in South Korean issuers may subject the Fund to legal, regulatory, political, currency, security, and economic risks that are specific to South Korea. In addition, economic and political developments of South Korea’s neighbors may have an adverse effect on the South Korean economy. Risks of Investing in Taiwan — Investments in Taiwanese issuers may subject the Fund to risks. Taiwan is a small island state with few raw material resources and limited land area and is reliant on imports for its commodity needs. Any fluctuations or shortages in the commodity markets could have a negative impact on the Taiwanese economy. Also, continued labor outsourcing may adversely affect the Taiwanese economy. Taiwan’s economy is intricately linked with economies of Asian countries that have experienced over-extensions of credit, frequent and pronounced currency fluctuations, currency devaluations, currency repatriation, rising unemployment and fluctuations in inflation. The Taiwanese economy is dependent on the economies of Japan and China, as well as the United States, and negative changes in their economies or a reduction in purchases by any of them of Taiwanese products and services would likely have an adverse impact on the Taiwanese economy. Taiwan’s geographic proximity to China and Taiwan’s history of political contention with China have resulted in ongoing tensions with China, including the risk of war with China. These tensions may materially affect the Taiwanese economy and securities markets. Issuer Risk — Fund performance depends on the performance of individual securities to which the Fund has exposure. Changes in the financial condition or credit rating of an issuer of those securities may cause the value of the securities to decline. Management Risk — As the Fund may not fully replicate the Underlying Index, it is subject to the risk that BlackRock’s investment strategy may not produce the intended results. 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. Valuation Risk — The sale price the Fund could receive for a security or other asset may differ from the Fund’s valuation of the security or other asset and from the value used by the Underlying Index, particularly for securities or other assets that trade in low volume or volatile markets or that are valued using a fair value methodology. In addition, the value of the securities or other assets in the Fund’s portfolio may change on days when shareholders will not be able to purchase or sell the Fund’s shares.
Risk Lose Money [Text]	rr_RiskLoseMoney	You may lose part or all of your investment in the Fund or your investment may not perform as well as other similar investments.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Performance Information
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	Because the Fund does not have a full calendar year of operations as of the date of this prospectus, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund. The Fund’s benchmark is the Underlying Index. Information on the Fund’s performance, including its current net asset value, can be obtained by visiting http://www.blackrock.com/funds or can be obtained by phone at (800) 882-0052.
Performance One Year or Less [Text]	rr_PerformanceOneYearOrLess	Because the Fund does not have a full calendar year of operations as of the date of this prospectus, it does not have performance information an investor would find useful in evaluating the risks of investing in the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	(800) 882-0052
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	http://www.blackrock.com/funds
Institutional | BlackRock MSCI Asia ex Japan Index Fund | Institutional Shares
Risk/Return:	rr_RiskReturnAbstract
Management Fee	rr_ManagementFeesOverAssets	0.25%	[1]
Distribution and/or Service (12b-1) Fees	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.91%	[2],[3]
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	1.16%	[3]
Fee Waivers and/or Expense Reimbursements	rr_FeeWaiverOrReimbursementOverAssets	(0.66%)	[1],[4]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements	rr_NetExpensesOverAssets	0.50%	[1],[4]
1 Year	rr_ExpenseExampleYear01	$ 51
3 Years	rr_ExpenseExampleYear03	303
5 Years	rr_ExpenseExampleYear05	575
10 Years	rr_ExpenseExampleYear10	$ 1,350

[1] As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 26, BlackRock Advisors, LLC (“BlackRock”) has contractually agreed to waive the management fee with respect to any portion of the Fund’s assets estimated to be attributable to investments in other equity and fixed-income mutual funds and exchange-traded funds managed by BlackRock or its affiliates that have a contractual management fee, through November 30, 2017. The contractual 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.

[2] Other Expenses have been restated to reflect current fees.

[3] The Total Annual Fund Operating Expenses do not correlate to the ratio of expenses to average net assets given in the Fund’s most recent annual report, which does not include the restatement of Other Expenses to reflect current fees.

[4] As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 26, 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 0.50% of average daily net assets through November 30, 2017. The Fund may have to repay some of these waivers and/or reimbursements to BlackRock in the following two years. The contractual 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.