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Class K | BlackRock Total Factor Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Fund Overview Key Facts About BlackRock Total Factor Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of BlackRock Total Factor Fund (“Total Factor Fund”or the “Fund”), a series of BlackRock FundsSM (the “Trust”), is to seek total return.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Fund
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
This table describes the fees and expenses that you may pay if you buy, hold and sell 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] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination June 30, 2024
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 July 31, 2022, the Fund’s portfolio turnover rate was 101% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 101.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text] rr_ExpensesNotCorrelatedToRatioDueToAcquiredFundFees 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 Acquired Fund Fees and Expenses.
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
Total Factor Fund seeks to achieve its investment objective by investing in a broad range of global asset classes, such as equity securities (which may include derivative instruments that are tied economically to equity securities), fixed and floating rate debt instruments, derivatives, other investment companies, including exchange-traded funds (“ETFs”), real estate investment trusts (“REITs”) and commodity-related instruments. The Fund will have flexibility with respect to the relative weighting of each asset class to produce total return and reduce risk.
The Fund applies a factor-based approach to portfolio construction to seek to more efficiently generate total return from a risk/return perspective than a traditional combination of equity and fixed-income securities. Through its research, BlackRock has identified macro and style factors that can drive returns across and within asset classes. BlackRock uses this research to determine allocations of the portfolio with reference to these factors and translates those allocations into asset classes. Such allocation across a range of asset classes and factors can lead to greater diversification and lower risk than a portfolio consisting solely of global equity securities. In determining the appropriate allocation across asset classes, the Fund will seek to manage exposure to macroeconomic factors, including, but not limited to, interest rates and economic growth and style factors, including, but not limited to, value, momentum, carry, and defensive factors. Allocations are computed not only in terms of capital but also in terms of risk in an effort to avoid overconcentration in any particular factor and to broaden the sources of potential returns.
The Fund will normally invest in both U.S. and non-U.S. companies, including companies located in emerging markets and in securities denominated in both U.S. dollars and foreign currencies. Equity securities include common stock, preferred stock, securities convertible into common stock, non-convertible preferred stock and depositary receipts. The Fund may invest in securities of issuers of any market capitalization.
The Fund’s investment in debt securities may include fixed and floating rate government and corporate bonds and other fixed-income instruments, such as medium term notes. The Fund may invest in debt securities of any credit quality, as determined by Fund management, which may include high yield securities (commonly called “junk bonds”).
The Fund may invest in derivatives, including but not limited to, total return swaps (some of which may be referred to as contracts for difference), credit default swaps, interest rate swaps, options, futures, options on futures and swaps and foreign exchange transactions, for hedging purposes, as well as to enhance the return on its portfolio investments. There is no limit to the Fund’s ability to invest in derivatives. The Fund may also invest in indexed and inverse securities. The Fund may engage in short sales of securities either to hedge against potential declines in the value of a security held in the portfolio or to realize appreciation when a security the Fund does not own declines in value.
The Fund may invest in other investment companies, including ETFs, which may be affiliated with BlackRock.
With respect to its cash investments, the Fund may hold high quality U.S. and non-U.S. money market securities, including, among others, short term U.S. Government securities, U.S. Government agency securities, securities issued by U.S. Government-sponsored enterprises and U.S. Government instrumentalities, short-term obligations of foreign issuers, bank obligations, commercial paper, including asset-backed commercial paper, corporate notes, repurchase agreements and obligations of supranational organizations. The Fund may invest a significant portion of its assets in money market funds, including those advised by BlackRock or its affiliates.
The Fund may invest in REITs and other real estate related securities.
The Fund may invest in commodity-related instruments. The Fund may make such investments through investments in BlackRock Cayman Strategic Risk Allocation Fund, Ltd. (the “Subsidiary”), a wholly-owned subsidiary of the Fund formed in the Cayman Islands, which invests primarily in commodity-related instruments and other derivatives. The Fund will not invest more than 25% of its total assets (measured at the time of investment) in the Subsidiary.
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 Total Factor 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 relative significance of each risk factor below may change over time and you should review each risk factor carefully. 
■ 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.
■ Debt Securities Risk — Debt securities, such as bonds, involve interest rate risk, credit risk, extension risk, and prepayment risk, among other things.
  Interest Rate Risk — The market value of bonds and other fixed-income securities changes in response to interest rate changes and other factors. Interest rate risk is the risk that prices of bonds and other fixed-income securities will increase as interest rates fall and decrease as interest rates rise.
  The Fund may be subject to a greater risk of rising interest rates due to the recent period of historically low interest rates. For example, if interest rates increase by 1%, assuming a current portfolio duration of ten years, and all other factors being equal, the value of the Fund’s investments would be expected to decrease by 10%. (Duration is a measure of the price sensitivity of a debt security or portfolio of debt securities to relative changes in interest rates.) The magnitude of these fluctuations in the market price of bonds and other fixed-income securities is generally greater for those securities with longer maturities. Fluctuations in the market price of the Fund’s investments will not affect interest income derived from instruments already owned by the Fund, but will be reflected in the Fund’s net asset value. The Fund may lose money if short-term or long-term interest rates rise sharply in a manner not anticipated by Fund management.
  To the extent the Fund invests in debt securities that may be prepaid at the option of the obligor (such as mortgage-backed securities), the sensitivity of such securities to changes in interest rates may increase (to the detriment of the Fund) when interest rates rise. Moreover, because rates on certain floating rate debt securities typically reset only periodically, changes in prevailing interest rates (and particularly sudden and significant changes) can be expected to cause some fluctuations in the net asset value of the Fund to the extent that it invests in floating rate debt securities.
  These basic principles of bond prices also apply to U.S. Government securities. A security backed by the “full faith and credit” of the U.S. Government is guaranteed only as to its stated interest rate and face value at maturity, not its current market price. Just like other fixed-income securities, government-guaranteed securities will fluctuate in value when interest rates change.
  A general rise in interest rates has the potential to cause investors to move out of fixed-income securities on a large scale, which may increase redemptions from funds that hold large amounts of fixed-income securities. Heavy redemptions could cause the Fund to sell assets at inopportune times or at a loss or depressed value and could hurt the Fund’s performance.
  Credit Risk — Credit risk refers to the possibility that the issuer of a debt security (i.e., the borrower) will not be able to make payments of interest and principal when due. Changes in an issuer’s credit rating or the market’s perception of an issuer’s creditworthiness may also affect the value of the Fund’s investment in that issuer. The degree of credit risk depends on both the financial condition of the issuer and the terms of the obligation.
  Extension Risk — When interest rates rise, certain obligations will be paid off by the obligor more slowly than anticipated, causing the value of these obligations to fall.
  Prepayment Risk — When interest rates fall, certain obligations will be paid off by the obligor more quickly than originally anticipated, and the Fund may have to invest the proceeds in securities with lower yields.
■ Investment in Other Investment Companies Risk — As with other investments, investments in other investment companies, including ETFs, are subject to market and selection risk. In addition, if the Fund acquires shares of investment companies, including ones affiliated with the Fund, shareholders bear both their proportionate share of expenses in the Fund (including management and advisory fees) and, indirectly, the expenses of the investment companies (to the extent not offset by BlackRock through waivers). To the extent the Fund is held by an affiliated fund, the ability of the Fund itself to hold other investment companies may be limited.
■ Indexed and Inverse Securities Risk — Indexed and inverse 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 and inverse 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.
■ 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:
  Leverage Risk — The Fund’s use of derivatives can magnify the Fund’s gains and losses. Relatively small market movements may result in large changes in the value of a derivatives position and can result in losses that greatly exceed the amount originally invested.
  Market Risk — Some derivatives are more sensitive to interest rate changes and market price fluctuations than other securities. The Fund could also suffer losses related to its derivatives positions as a result of unanticipated market movements, which losses are potentially unlimited. Finally, BlackRock may not be able to predict correctly the direction of securities prices, interest rates and other economic factors, which could cause the Fund’s derivatives positions to lose value.
  Counterparty Risk — Derivatives are also subject to counterparty risk, which is the risk that the other party in the transaction will be unable or unwilling to fulfill its contractual obligation, and the related risks of having concentrated exposure to such a counterparty.
  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.
  Operational Risk — The use of derivatives includes the risk of potential operational issues, including documentation issues, settlement issues, systems failures, inadequate controls and human error.
  Legal Risk — The risk of insufficient documentation, insufficient capacity or authority of counterparty, or legality or enforceability of a contract.
  Volatility and Correlation 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.
  Valuation Risk — Valuation for derivatives may not be readily available in the market. 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 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, with respect to uncleared swaps, swap dealers are required to collect variation margin from the Fund and may be required by applicable regulations to collect initial margin from the Fund. Both initial and variation margin may be comprised of cash and/or securities, subject to applicable regulatory haircuts. Shares of investment companies (other than certain money market funds) may not be posted as collateral under applicable regulations. 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.
■ Commodities Related Investments Risk — Exposure to the commodities markets may subject the Fund to greater volatility than investments in traditional securities. The value of commodity-linked derivative investments may be affected by changes in overall market movements, commodity index volatility, changes in interest rates, or factors 
  affecting a particular industry or commodity, such as drought, floods, weather, embargoes, tariffs and international economic, political and regulatory developments.
■ 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 — 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.
■ 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.
■ 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 as well as acts of war in the region. These events may spread to other countries in Europe and may affect the value and liquidity of certain of the Fund’s investments. 
■ Investment Style Risk — Certain investment styles may over time go in and out of favor. At times when an investment style used by the Fund is out of favor, the Fund may underperform other funds that use different investment styles.
■ Junk Bonds Risk — Although junk bonds generally pay higher rates of interest than investment grade bonds, junk bonds are high risk investments that are considered speculative and may cause income and principal losses for the Fund. 
■ 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 the applicable requirements of the Investment Company Act of 1940, as amended (the “Investment Company Act”), and the rules thereunder. 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. This means you may lose money.
  An outbreak of an infectious coronavirus (COVID-19) that was first detected in December 2019 developed into a global pandemic that has resulted in numerous disruptions in the market and has had significant economic impact leaving general concern and uncertainty. Although vaccines have been developed and approved for use by various governments, the duration of the pandemic and its effects cannot be predicted with certainty. The impact of this coronavirus, and other epidemics and pandemics that may arise in the future, could affect the economies of many nations, individual companies and the market in general ways that cannot necessarily be foreseen at the present time.
■ 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.
■ Preferred Securities Risk — Preferred securities may pay fixed or adjustable rates of return. Preferred securities are subject to issuer-specific and market risks applicable generally to equity securities. In addition, a company’s preferred securities generally pay dividends only after the company makes required payments to holders of its bonds and other debt. For this reason, the value of preferred securities will usually react more strongly than bonds and other debt to actual or perceived changes in the company’s financial condition or prospects. Preferred securities of smaller companies may be more vulnerable to adverse developments than preferred securities of larger companies.
■ 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 may also affect real estate values. If the Fund’s real estate-related investments are concentrated in one geographic area or in one property type, the Fund will be particularly subject to the risks associated with that area or property type. Many issuers of real estate-related securities are highly leveraged, which increases the risk to holders of such securities. The value of the securities the Fund buys will not necessarily track the value of the underlying investments of the issuers of such securities. 
■ REIT Investment Risk — Investments in REITs involve unique risks. REITs may have limited financial resources, may trade less frequently and in limited volume, may engage in dilutive offerings of securities and may be more volatile than other securities. REIT issuers may also fail to maintain their exemptions from investment company registration or fail to qualify for the “dividends paid deduction” under the Internal Revenue Code of 1986, as amended (the “Internal Revenue Code”), which allows REITs to reduce their corporate taxable income for dividends paid to their shareholders.
■ Repurchase Agreements Risk— If the other party to a repurchase agreement defaults on its obligation under the agreement, the Fund may suffer delays and incur costs or lose money in exercising its rights under the agreement. If the seller fails to repurchase the security and the market value of the security declines, the Fund may lose money.
■ 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.
■ Sovereign Debt Risk — Sovereign debt instruments are subject to the risk that a governmental entity may delay or refuse to pay interest or repay principal on its sovereign debt, due, for example, to cash flow problems, insufficient foreign currency reserves, political considerations, the relative size of the governmental entity’s debt position in relation to the economy or the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies.
■ Subsidiary Risk — By investing in the Subsidiary, the Fund is indirectly exposed to the risks associated with the Subsidiary’s investments. The commodity-related instruments held by the Subsidiary are generally similar to those that are permitted to be held by the Fund and are subject to the same risks that apply to similar investments if held directly by the Fund (see “Commodities Related Investments Risk” above). There can be no assurance that the investment objective of the Subsidiary will be achieved. The Subsidiary is not registered under the Investment Company Act, and, unless otherwise noted in this prospectus, is not subject to all the investor protections of the Investment Company Act. However, the Fund wholly owns and controls the Subsidiary, and the Fund and the Subsidiary are both managed by BlackRock, making it unlikely that the Subsidiary will take action contrary to the interests of the Fund and its shareholders. The Board has oversight responsibility for the investment activities of the Fund, including its investment in the Subsidiary, and the Fund’s role as sole shareholder of the Subsidiary. The Subsidiary is subject to the same investment restrictions and limitations, and follows the same compliance policies and procedures, as the Fund except that the Subsidiary may invest without limitation in commodity-related instruments. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Fund and/or the Subsidiary to operate as described in this prospectus and the Statement of Additional Information and could adversely affect the Fund.
■ Supranational Entities Risk — The Fund may invest in obligations issued or guaranteed by the International Bank for Reconstruction and Development (the “World Bank”). The government members, or “stockholders,” usually make initial capital contributions to the World Bank and in many cases are committed to make additional capital contributions if the World Bank is unable to repay its borrowings. There is no guarantee that one or more stockholders of the World Bank will continue to make any necessary additional capital contributions. If such contributions are not made, the entity may be unable to pay interest or repay principal on its debt securities, and the Fund may lose money on such investments.
■ 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.
■ U.S. Government Obligations Risk — Certain securities in which the Fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States.
■ Variable and Floating Rate Instrument Risk — Variable and floating rate securities provide for periodic adjustment in the interest rate paid on the securities. These securities may be subject to greater illiquidity risk than other fixed income securities, meaning the absence of an active market for these securities could make it difficult for the Fund to dispose of them at any given time.
■ Volatility Risk — Although the Fund intends to implement strategies designed to limit volatility during times of market stress, the effectiveness of these strategies may depend on particular market conditions and other factors that are beyond the control of Fund management. There can be no assurance that the Fund’s efforts to limit volatility will be successful or that any particular level of volatility will be achieved. 
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
The Fund’s Annual Total Returns between December 27, 2012 (commencement of operations) and February 2, 2017 as reflected in the bar chart and the table are the returns of the Fund that followed a different investment process and different investment strategies under the name “BlackRock Strategic Risk Allocation Fund.”
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 February 3, 2017. As a result, returns show below for Class K Shares prior to February 3, 2017 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 Institutional Shares and Class K Shares have different expenses. The actual returns of Class K Shares would have been higher than those of the Institutional Shares because Class K Shares have lower expenses than the Institutional Shares. The table compares the Fund’s performance to that of the MSCI World Index Hedged USD Net, the Bloomberg U.S. Aggregate Bond Index, a customized weighted index comprised of the returns of the the MSCI World Index Hedged USD Net (60%) and the Bloomberg U.S. Aggregate Bond Index (40%) and 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 www.blackrock.com 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
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 Class K Shares ANNUAL TOTAL RETURNS BlackRock Total Factor Fund As of 12/31
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
During the periods shown in the bar chart, the highest return for a quarter was 4.86% (quarter ended March 31, 2019) and the lowest return for a quarter was -12.43% (quarter ended March 31, 2020). The year-to-date return as of September 30, 2022 was -10.26%.
Performance Table Heading rr_PerformanceTableHeading For the periods ended 12/31/21 Average Annual Total Returns
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 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.
Class K | BlackRock Total Factor Fund | Class K Shares  
Risk/Return: rr_RiskReturnAbstract  
Management Fee rr_ManagementFeesOverAssets 0.50% [1]
Distribution and/or Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses of the Fund rr_Component1OtherExpensesOverAssets 0.42%
Other Expenses of the Subsidiary rr_Component2OtherExpensesOverAssets [2]
Other Expenses rr_OtherExpensesOverAssets 0.42% [2]
Acquired Fund Fees and Expenses rr_AcquiredFundFeesAndExpensesOverAssets 0.01% [3]
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.93% [3]
Fee Waivers and/or Expense Reimbursements rr_FeeWaiverOrReimbursementOverAssets (0.42%) [1],[4]
Total Annual Fund Operating Expenses After Fee Waivers and/or Expense Reimbursements rr_NetExpensesOverAssets 0.51% [1],[4]
1 Year rr_ExpenseExampleYear01 $ 52
3 Years rr_ExpenseExampleYear03 254
5 Years rr_ExpenseExampleYear05 474
10 Years rr_ExpenseExampleYear10 $ 1,104
2013 rr_AnnualReturn2013 (1.88%)
2014 rr_AnnualReturn2014 9.21%
2015 rr_AnnualReturn2015 (4.37%)
2016 rr_AnnualReturn2016 8.85%
2017 rr_AnnualReturn2017 10.24%
2018 rr_AnnualReturn2018 (2.36%)
2019 rr_AnnualReturn2019 7.96%
2020 rr_AnnualReturn2020 (15.29%)
2021 rr_AnnualReturn2021 16.73%
Year to Date Return, Label rr_YearToDateReturnLabel year-to-date return
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2022
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn (10.26%)
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest return
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2019
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 4.86%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest return
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.43%)
1 Year rr_AverageAnnualReturnYear01 16.73%
5 Years rr_AverageAnnualReturnYear05 2.82%
Since Inception rr_AverageAnnualReturnSinceInception 2.76%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 27, 2012
Class K | BlackRock Total Factor Fund | Return After Taxes on Distributions | Class K Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 14.94%
5 Years rr_AverageAnnualReturnYear05 1.66%
Since Inception rr_AverageAnnualReturnSinceInception 1.44%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 27, 2012
Class K | BlackRock Total Factor Fund | Return After Taxes on Distributions and Sale of Fund Shares | Class K Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 9.90%
5 Years rr_AverageAnnualReturnYear05 1.68%
Since Inception rr_AverageAnnualReturnSinceInception 1.52%
Inception Date rr_AverageAnnualReturnInceptionDate Dec. 27, 2012
Class K | BlackRock Total Factor Fund | MSCI World Index Hedged USD Net (Reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 24.38%
5 Years rr_AverageAnnualReturnYear05 15.23%
Since Inception rr_AverageAnnualReturnSinceInception 13.81%
Class K | BlackRock Total Factor Fund | Bloomberg U.S. Aggregate Bond Index (Reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 (1.54%)
5 Years rr_AverageAnnualReturnYear05 3.57%
Since Inception rr_AverageAnnualReturnSinceInception 2.74%
Class K | BlackRock Total Factor Fund | MSCI World Index Hedged USD Net (60%)/Bloomberg U.S. Aggregate Bond Index (40%) (Reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 13.45%
5 Years rr_AverageAnnualReturnYear05 10.70%
Since Inception rr_AverageAnnualReturnSinceInception 9.47%
Class K | BlackRock Total Factor Fund | ICE BofA 3-Month U.S. Treasury Bill Index (Reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 0.05% [5]
5 Years rr_AverageAnnualReturnYear05 1.14% [5]
Since Inception rr_AverageAnnualReturnSinceInception 0.69% [5]
[1] As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 35, 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 June 30, 2024. In addition, BlackRock has contractually agreed to waive its management fees by the amount of investment advisory fees the Fund pays to BlackRock indirectly through its investment in money market funds managed by BlackRock or its affiliates, through June 30, 2024. The contractual agreements 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] The Other Expenses of the BlackRock Cayman Strategic Risk Allocation Fund, Ltd. (the “Subsidiary”) were less than 0.01% for the most recent fiscal year.
[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 Acquired Fund Fees and Expenses.
[4] As described in the “Management of the Fund” section of the Fund’s prospectus beginning on page 35, 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 June 30, 2024. 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.
[5] On March 1, 2021, the Fund began to track the 4pm pricing variant of the ICE BofA 1-3 Year U.S. Treasury Bill Index (the “Index”). Historical index data prior to March 1, 2021 is for the 3pm pricing variant of the Index. Index data on and after March 1, 2021 is for the 4 pm pricing variant of the Index.