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DFA Commodity Strategy Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading DFA Commodity Strategy Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock
The investment objective of the DFA Commodity Strategy Portfolio (the “Portfolio”) is to seek total return consisting of capital appreciation and current income.
Expense [Heading] rr_ExpenseHeading Fees and Expenses of the Portfolio
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock
This table describes the fees and expenses you may pay if you buy, hold or sell shares of the DFA Commodity Strategy Portfolio. You may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table and Example below. 
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment):
Operating Expenses Caption [Text] rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses that you pay each year as a percentage of the value of your investment)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading PORTFOLIO TURNOVER
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock
The DFA Commodity Strategy Portfolio 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 Portfolio shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Portfolio’s performance. During the most recent fiscal year, the Portfolio’s portfolio turnover rate was 114% of the average value of its investment portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 114.00%
Expense Example [Heading] rr_ExpenseExampleHeading EXAMPLE
Expense Example Narrative [Text Block] rr_ExpenseExampleNarrativeTextBlock
This Example is meant to help you compare the cost of investing in the DFA Commodity Strategy Portfolio with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Portfolio for the time periods indicated. The Example also assumes that your investment has a 5% return each year and that the Portfolio’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
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock
The DFA Commodity Strategy Portfolio seeks to achieve its investment objective by generally investing in a universe of allowable commodity-linked derivative instruments and fixed income investment opportunities. The Portfolio gains exposure to commodities markets by investing in derivative instruments, such as structured notes whose principal and/or coupon payments are linked to commodities or commodity indices, in swap agreements, and/or in other commodity-linked instruments (such as futures contracts on individual commodities or commodity indices). The Portfolio may invest up to 25% of its total assets in Dimensional Cayman Commodity Fund I Ltd. (the “Subsidiary”), a wholly-owned subsidiary of the Portfolio formed in the Cayman Islands, which has the same
  
investment objective as the Portfolio and has a strategy of investing in derivative instruments, such as commodity-linked swap agreements and other commodity-linked instruments, futures contracts on individual commodities or commodity indices, and options on these instruments. The Portfolio, directly and/or through its investment in the Subsidiary, expects to use such derivatives extensively as part of its investment strategy. 
The DFA Commodity Strategy Portfolio will invest in obligations issued or guaranteed by the U.S. and foreign governments, their agencies and instrumentalities, bank obligations, commercial paper, repurchase agreements, money market funds, obligations of other domestic and foreign issuers having investment grade ratings (e.g., rated AAA to BBB- by S&P Global Ratings (“S&P”) or Fitch Ratings Ltd. (“Fitch”) or Aaa to Baa3 by Moody’s Investors Service, Inc. (“Moody’s”)), securities of domestic or foreign issuers denominated in U.S. dollars but not trading in the United States, and obligations of supranational organizations. Dimensional Fund Advisors LP (the “Advisor”) expects that the Portfolio will primarily invest in the obligations of issuers that are in developed countries. The fixed income securities in which the Portfolio invests are considered investment grade at the time of purchase. In addition, the Portfolio is authorized to invest more than 25% of its total assets in U.S. Treasury bonds, bills and notes, and obligations of federal agencies and instrumentalities. 
The DFA Commodity Strategy Portfolio’s fixed income securities primarily will mature within five years from the date of settlement, and the Portfolio maintains an average portfolio duration of three years or less. Duration is a measure of the sensitivity of a security’s price to changes in interest rates. The longer a security’s duration, the more sensitive it will be to changes in interest rates. Similarly, a portfolio with a longer average portfolio duration will be more sensitive to changes in interest rates than a fund with a shorter average portfolio duration. In making purchase decisions, if the expected term premium is greater for longer-term securities in the eligible maturity range, the Advisor will focus investment in the longer-term area, otherwise, the Portfolio will focus investment in the shorter-term area of the eligible maturity range. 
The DFA Commodity Strategy Portfolio’s investments may include foreign securities denominated in foreign currencies. The Portfolio intends to hedge foreign currency exposure to protect against uncertainty in the level of future foreign currency rates, to hedge against fluctuations in currency exchange rates or to transfer balances from one currency to another. The Portfolio may hedge such currency exposure by entering into foreign currency forward contracts. The Portfolio also may enter into credit default swaps on issuers or indices to buy or sell credit protection to hedge its credit exposure, gain market or issuer exposure without owning the underlying securities, or increase the Portfolio’s expected total return. The Portfolio may purchase or sell futures contracts and options on futures contracts, to hedge its currency exposure or to hedge its interest rate exposure or for non-hedging purposes, such as a substitute for direct investment or to increase or decrease market exposure based on actual or expected cash inflows to or outflows from the Portfolio. 
The DFA Commodity Strategy Portfolio may lend its portfolio securities to generate additional income. 
Risk [Heading] rr_RiskHeading Principal Risks
Risk Narrative [Text Block] rr_RiskNarrativeTextBlock
Because the value of your investment in the DFA Commodity Strategy Portfolio will fluctuate, there is the risk that you will lose money. An investment in the Portfolio is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. The following is a description of principal risks of investing in the Portfolio.
Market Risk: Even a long-term investment approach cannot guarantee a profit. Economic, political, and issuer-specific events will cause the value of securities, and the Portfolio that owns them, to rise or fall.
Commodity Risk: The value of commodity-linked derivative instruments 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, livestock disease, embargoes, tariffs, and international economic, political, and regulatory developments.
  
Derivatives Risk: Derivatives are instruments, such as futures, and options thereon, foreign currency forward contracts and swaps, whose value is derived from that of other assets, rates or indices. Derivatives can be used for hedging (attempting to reduce risk by offsetting one investment position with another) or non-hedging purposes. While hedging can reduce or eliminate losses, it also can reduce or eliminate gains or cause losses if the market moves in a manner different from that anticipated by the Portfolio or if the cost of the derivative outweighs the benefit of the hedge. In regard to currency hedging, it is generally not possible to precisely match the foreign currency exposure of such foreign currency forward contracts to the value of the securities involved due to fluctuations in the market values of such securities and cash flows into and out of the Portfolio between the date a foreign currency forward contract is entered into and the date it expires. The use of derivatives for non-hedging purposes may be considered to carry more risk than other types of investments. When the Portfolio uses derivatives, the Portfolio will be directly exposed to the risks of those derivatives. Derivative instruments are subject to a number of risks, including commodity, counterparty, correlation, interest rate, liquidity, market, credit and management risks, as well as the risk of improper valuation. The Portfolio also may use derivatives for leverage. The Portfolio’s use of derivatives, particularly commodity-linked derivatives, involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other traditional investments. Use of leveraged commodity-linked derivatives creates an opportunity for increased return but, at the same time, creates the possibility for greater loss (including the likelihood of greater volatility of the Portfolio’s net asset value), and there can be no assurance that the Portfolio’s use of leverage will be successful. Changes in the value of a derivative may not correlate perfectly with the underlying asset, rate, or index, and the Portfolio could lose more than the principal amount invested. For example, potential losses from commodity-linked notes or swap agreements can be unlimited. Additional risks are associated with the use of credit default swaps, including counterparty and credit risk (the risk that the other party to a swap agreement will not fulfill its contractual obligations, whether because of bankruptcy or other default), and settlement risk (the risk faced when one party to a transaction has performed its obligations under a contract but has not yet received value from its counterparty). and liquidity risk (the possible lack of a secondary market for the swap agreement). Also, suitable derivative transactions may not be available in all circumstances and there can be no assurance that the Portfolio will engage in these transactions to reduce exposure to other risks when that would be beneficial. 
Focus Risk: The Portfolio may be exposed, from time to time, to the performance of a small number of commodity sectors (e.g., energy, metals or agricultural), which may represent a large portion of the Portfolio. As a result, the Portfolio may be subject to greater volatility than if the Portfolio were more broadly diversified among commodity sectors. 
Foreign Securities and Currencies Risk: Foreign securities prices may decline or fluctuate because of: (a) economic or political actions of foreign governments, and/or (b) less regulated or liquid securities markets. Investors holding these securities may also be exposed to foreign currency risk (the possibility that foreign currency will fluctuate in value against the U.S. dollar or that a foreign government will convert, or be forced to convert, its currency to another currency, changing its value against the U.S. dollar). The Portfolio hedges foreign currency risk. 
Foreign Government Debt Risk: The risk that: (a) the governmental entity that controls the repayment of government debt may not be willing or able to repay the principal and/or to pay the interest when it becomes due, due to factors such as political considerations, the relative size of the governmental entity’s debt position in relation to the economy, cash flow problems, insufficient foreign currency reserves, the failure to put in place economic reforms required by the International Monetary Fund or other multilateral agencies, and/or other national economic factors; (b) governments may default on their debt securities, which may require holders of such securities to participate in debt rescheduling; and (c) there is no legal or bankruptcy process by which defaulted government debt may be collected in whole or in part. 
Interest Rate Risk: Fixed income securities are subject to interest rate risk because the prices of fixed income securities tend to move in the opposite direction of interest rates. When interest rates rise, fixed income security prices fall. When interest rates fall, fixed income security prices rise. In general, fixed income securities with longer maturities are more sensitive to changes in interest rates. The Portfolio may be subject to a greater risk of rising interest rates due to the current period of historically low interest rates. 
Credit Risk: Credit risk is the risk that the issuer of a security, or the counterparty to an agreement or contract, including a derivative instrument, such as a credit default swap, may be unable or unwilling to meet its financial 
obligations. A downgrade to an issuer’s credit rating or a perceived change in an issuer’s financial strength may affect a security’s value, and thus, impact the Portfolio’s performance. Government agency obligations have different levels of credit support and, therefore, different degrees of credit risk. Securities issued by agencies and instrumentalities of the U.S. Government that are supported by the full faith and credit of the United States, such as the Federal Housing Administration and Ginnie Mae, present little credit risk. Other securities issued by agencies and instrumentalities sponsored by the U.S. Government, that are supported only by the issuer’s right to borrow from the U.S. Treasury, subject to certain limitations, and securities issued by agencies and instrumentalities sponsored by the U.S. Government that are sponsored by the credit of the issuing agencies, such as Freddie Mac and Fannie Mae, are subject to a greater degree of credit risk. U.S. government agency securities issued or guaranteed by the credit of the agency may still involve a risk of non-payment of principal and/or interest. 
Call Risk: Call risk is the risk that during periods of falling interest rates, an issuer will call or repay a higher-yielding fixed income security before its maturity date, forcing the Portfolio to reinvest in fixed income securities with lower interest rates than the original obligations. 
Liquidity Risk: Certain portfolio holdings, such as commodity-linked derivative instruments and swap agreements, may be difficult or impossible to sell at the time and the price that the Portfolio would like. The Portfolio may have to lower the price, sell other holdings instead, or forego an investment opportunity. Any of these could have a negative effect on management of the Portfolio or the Portfolio’s performance. 
Subsidiary Risk: By investing in the Subsidiary, the Portfolio is indirectly exposed to the risks associated with the Subsidiary’s investments. The derivatives and other investments held by the Subsidiary are generally similar to those that are permitted to be held by the Portfolio and are subject to the same risks that apply to similar investments if held directly by the Portfolio. These risks are described elsewhere in this Prospectus. 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 of 1940, as amended (the “1940 Act”), and, unless otherwise noted in this Prospectus, is not subject to all of the investor protections of the 1940 Act. However, the Portfolio wholly owns and controls the Subsidiary, and the Portfolio and the Subsidiary are both managed by the Advisor, making it unlikely that the Subsidiary will take action contrary to the interests of the Portfolio and its shareholders. The Board of Directors of DFA Investment Dimensions Group Inc. (the “Fund”) has oversight responsibility for the investment activities of the Portfolio, including its investment in the Subsidiary, and the Portfolio’s role as the sole shareholder of the Subsidiary. The Subsidiary will be subject to investment restrictions and limitations and compliance policies and procedures substantially similar to those imposed on the Portfolio by the 1940 Act. Changes in the laws of the United States and/or the Cayman Islands could result in the inability of the Portfolio and/or the Subsidiary to continue to operate as it does currently and could adversely affect the Portfolio. For example, the Cayman Islands currently do not impose any income, corporate, or capital gains tax, estate duty, inheritance tax, gift tax, or withholding tax on the Subsidiary. If Cayman Islands law changes, such that the Subsidiary must pay Cayman Islands taxes, Portfolio shareholders likely would suffer decreased investment returns. 
Tax Risk: The tax treatment of commodity-linked derivative instruments may be adversely affected by changes in legislation, regulations or other legally binding authority. If, as a result of any such adverse action, the income of the Portfolio from certain commodity-linked derivatives was treated as non-qualifying income, the Portfolio might fail to qualify as a regulated investment company and be subject to federal income tax at the Portfolio level. As a regulated investment company, the Portfolio must derive at least 90% of its gross income for each taxable year from sources treated as qualifying income under the Internal Revenue Code of 1986, as amended (the “Code”). The Portfolio has obtained private letter rulings from the Internal Revenue Service confirming that the income the Portfolio derives from a form of commodity-linked note and the Subsidiary constitutes qualifying income under the Code. However, the portion of such rulings regarding the treatment of commodity-linked notes held directly by the Portfolio was revoked because of changes in the IRS’s position. Despite the rulings, the Portfolio historically has not invested directly in commodity-linked notes. As a result, the Portfolio may invest in commodity-linked notes only: (a) directly, to the extent that such investments constitute securities under section 2(a)(36) of the 1940 Act (because such securities generate qualifying income to a regulated investment company, such as the Portfolio), (b) directly, to the extent that the Portfolio believes such investments would not prohibit the Portfolio from qualifying as a regulated investment company regardless of the status of the 
investment as a security under section 2(a)(36) of the 1940 Act, or (c) indirectly, as the Portfolio traditionally has done, through the Subsidiary. If the Portfolio does not appropriately limit such investments or if such investments (or the income earned on such investments) were to be recharacterized for U.S. tax purposes, the Portfolio could fail to qualify as a regulated investment company. In lieu of potential disqualification, the Portfolio is permitted to pay a tax for certain failures to satisfy the income requirement, which, in general, are limited to those due to reasonable cause and not willful neglect. The Portfolio also may incur transaction and other costs to comply with any new or additional guidance from the Internal Revenue Service. For more information, please see the “TAXATION OF THE PORTFOLIO AND ITS SHAREHOLDERS” section in the Portfolio’s Statement of Additional Information. 
Leveraging Risk: Certain transactions that the Portfolio may enter into may give rise to a form of leverage. Such transactions may include, among others, structured notes, swap agreements, futures contracts, and loans of portfolio securities. The use of leverage may cause the Portfolio to liquidate portfolio positions when it may not be advantageous to do so to satisfy its obligations or to meet segregation requirements. Leverage may cause the Portfolio to be more volatile than if the Portfolio had not been leveraged. This is because leverage tends to exaggerate the effect of any increase or decrease in the value of the Portfolio’s portfolio securities. 
Regulatory Risk: Governments, agencies, or other regulatory bodies may adopt or change laws or regulations that could adversely affect the issuer, the market value of the security, or the Portfolio’s performance. 
Valuation Risk: The lack of an active trading market may make it difficult to obtain an accurate price for a security held by the Portfolio. Many commodity-linked derivative instruments are not actively traded. 
Securities Lending Risk: Securities lending involves the risk that the borrower may fail to return the securities in a timely manner or at all. As a result, the Portfolio may lose money and there may be a delay in recovering the loaned securities. The Portfolio could also lose money if the Portfolio does not recover the securities and/or the value of the collateral falls, including the value of investments made with cash collateral. Securities lending also may have certain adverse tax consequences. 
Operational Risk: Operational risks include human error, changes in personnel, system changes, faults in communication, and failures in systems, technology, or processes. Various operational events or circumstances are outside the Advisor’s control, including instances at third parties. The Portfolio and the Advisor seek to reduce these operational risks through controls and procedures. However, these measures do not address every possible risk and may be inadequate to address these risks. 
Cyber Security Risk: The Portfolio’s and its service providers’ use of internet, technology and information systems may expose the Portfolio to potential risks linked to cyber security breaches of those technological or information systems. Cyber security breaches, amongst other things, could allow an unauthorized party to gain access to proprietary information, customer data, or fund assets, or cause the Portfolio and/or its service providers to suffer data corruption or lose operational functionality. 
Risk Lose Money [Text] rr_RiskLoseMoney Because the value of your investment in the DFA Commodity Strategy Portfolio will fluctuate, there is the risk that you will lose money.
Risk Not Insured Depository Institution [Text] rr_RiskNotInsuredDepositoryInstitution An investment in the Portfolio is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock
The bar chart and table immediately following illustrate the variability of the DFA Commodity Strategy Portfolio’s returns and are meant to provide some indication of the risks of investing in the Portfolio. The bar chart shows the changes in the Portfolio’s performance from year to year. The table illustrates how annualized one year, five year and ten year returns, both before and after taxes, compare with those of a broad measure of market performance. The Portfolio’s past performance (before and after taxes) is not an indication of future results. Updated performance information for the Portfolio can be obtained by visiting http://us.dimensional.com.
The after-tax returns presented in the table for the DFA Commodity Strategy Portfolio 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 an investor’s tax situation and may differ from those shown in the table. In addition, the after-tax returns shown are not relevant to investors who hold shares of the Portfolio through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table immediately following illustrate the variability of the DFA Commodity Strategy Portfolio’s returns and are meant to provide some indication of the risks of investing in the Portfolio. The bar chart shows the changes in the Portfolio’s performance from year to year.
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress http://us.dimensional.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The Portfolio’s past performance (before and after taxes) is not an indication of future results.
Bar Chart [Heading] rr_BarChartHeading DFA Commodity Strategy Portfolio Institutional Class Shares—Total Returns 
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
January 2012‑December 2021
Highest Quarter
  
Lowest Quarter
14.68% (4/21-6/21)
  
-22.51% (1/20–3/20)
Performance Table Heading rr_PerformanceTableHeading Annualized Returns (%)Periods ending December 31, 2021
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate The after-tax returns presented in the table for the DFA Commodity Strategy Portfolio 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 In addition, the after-tax returns shown are not relevant to investors who hold shares of the Portfolio through tax-advantaged arrangements, such as 401(k) plans or individual retirement accounts.
DFA Commodity Strategy Portfolio | DFA Commodity Strategy Portfolio Shares  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fee, Other rr_ShareholderFeeOther none
Management Fee rr_ManagementFeesOverAssets 0.28%
Other Expenses rr_OtherExpensesOverAssets 0.03%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.31%
1 Year rr_ExpenseExampleYear01 $ 32
3 Years rr_ExpenseExampleYear03 100
5 Years rr_ExpenseExampleYear05 174
10 Years rr_ExpenseExampleYear10 393
1 Year rr_ExpenseExampleNoRedemptionYear01 32
3 Years rr_ExpenseExampleNoRedemptionYear03 100
5 Years rr_ExpenseExampleNoRedemptionYear05 174
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 393
2012 rr_AnnualReturn2012 1.33%
2013 rr_AnnualReturn2013 (9.09%)
2014 rr_AnnualReturn2014 (14.62%)
2015 rr_AnnualReturn2015 (23.85%)
2016 rr_AnnualReturn2016 13.77%
2017 rr_AnnualReturn2017 2.73%
2018 rr_AnnualReturn2018 (11.21%)
2019 rr_AnnualReturn2019 7.96%
2020 rr_AnnualReturn2020 (1.78%)
2021 rr_AnnualReturn2021 28.46%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2021
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.68%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (22.51%)
1 Year rr_AverageAnnualReturnYear01 28.46%
5 Years rr_AverageAnnualReturnYear05 4.44%
10 Years rr_AverageAnnualReturnYear10 (1.65%)
DFA Commodity Strategy Portfolio | Return After Taxes on Distributions | DFA Commodity Strategy Portfolio Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 11.65%
5 Years rr_AverageAnnualReturnYear05 0.98%
10 Years rr_AverageAnnualReturnYear10 (3.44%)
DFA Commodity Strategy Portfolio | Return After Taxes on Distributions and Sale of Portfolio Shares | DFA Commodity Strategy Portfolio Shares  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 16.49%
5 Years rr_AverageAnnualReturnYear05 1.92%
10 Years rr_AverageAnnualReturnYear10 (1.96%)
DFA Commodity Strategy Portfolio | Bloomberg Commodity Index Total Return (reflects no deduction for fees, expenses, or taxes on sales)  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 27.11%
5 Years rr_AverageAnnualReturnYear05 3.66%
10 Years rr_AverageAnnualReturnYear10 (2.85%)