XML 258 R659.htm IDEA: XBRL DOCUMENT v3.8.0.1
Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName DFA INVESTMENT DIMENSIONS GROUP INC
Prospectus Date rr_ProspectusDate Feb. 28, 2018
R SHARES | U.S. Targeted Value Portfolio  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading U.S. Targeted Value Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Objective
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The investment objective of the U.S. Targeted Value Portfolio is to achieve long-term capital appreciation.
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 and hold shares of the U.S. Targeted Value Portfolio.
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 U.S. Targeted Value 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 U.S. Targeted Value Portfolio’s performance. During the most recent fiscal year, the U.S. Targeted Value Portfolio’s portfolio turnover rate was 23% of the average value of its investment portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 23.00%
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 U.S. Targeted Value 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 the 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 U.S. Targeted Value Portfolio, using a market capitalization weighted approach, purchases a broad and diverse group of the readily marketable securities of U.S. small and mid cap companies that Dimensional Fund Advisors LP (the “Advisor”) determines to be value stocks. A company’s market capitalization is the number of its shares outstanding times its price per share. In general, the higher the relative market capitalization of the eligible company, the greater its representation in the Portfolio. The Advisor may adjust the representation in the U.S. Targeted Value Portfolio of an eligible company, or exclude a company, after considering such factors as free float, momentum, trading strategies, liquidity, size, value, profitability, and other factors that the Advisor determines to be appropriate, given market conditions. Securities are considered value stocks primarily because a company’s shares have a low price in relation to their book value. In assessing value, the Advisor may consider additional factors such as price to cash flow and price to earnings ratios. In assessing profitability, the Advisor may consider different ratios, such as that of earnings or profits from operations relative to book value or assets. The criteria the Advisor uses for assessing value or profitability are subject to change from time to time.

As a non-fundamental policy, under normal circumstances, the U.S. Targeted Value Portfolio will invest at least 80% of its net assets in securities of U.S. companies. As of the date of this Prospectus, the Advisor considers for investment companies whose market capitalization are generally smaller than the 500th largest U.S. company. As of December 31, 2017, companies smaller than the 500th largest U.S. company fall in lowest 16% of total U.S. market capitalization. Total market capitalization is based on the market capitalization of U.S. operating companies listed on the New York Stock Exchange (“NYSE”), NYSE American LLC, Nasdaq Global Market®, Nasdaq Capital Market®, or such other securities exchanges deemed appropriate by the Advisor. Based on market capitalization data as of December 31, 2017, the market capitalization of a company smaller than the 500th largest U.S. company would be $8,793 million or below. This dollar amount will change due to market conditions.

The U.S. Targeted Value Portfolio may purchase or sell futures contracts and options on futures contracts for U.S. equity securities and indices, to adjust market exposure based on actual or expected cash inflows to or outflows from the Portfolio. The Portfolio does not intend to sell futures contracts to establish short positions in individual securities or to use derivatives for purposes of speculation or leveraging investment returns.

The U.S. Targeted Value 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 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.

Equity Market Risk: Even a long-term investment approach cannot guarantee a profit. Economic, market, political, and issuer-specific conditions and events will cause the value of equity securities, and the Portfolio that owns them, to rise or fall. Stock markets tend to move in cycles with periods of rising prices and periods of falling prices.

Small Company Risk: Securities of small companies are often less liquid than those of large companies and this could make it difficult to sell a small company security at a desired time or price. As a result, small company stocks may fluctuate relatively more in price. In general, smaller capitalization companies are also more vulnerable than larger companies to adverse business or economic developments and they may have more limited resources.

Value Investment Risk: Value stocks may perform differently from the market as a whole and following a value-oriented investment strategy may cause the Portfolio to at times underperform equity funds that use other investment strategies.

Derivatives Risk: Derivatives are instruments, such as futures contracts, whose value is derived from that of other assets, rates or indices. The use of derivatives for non-hedging purposes may be considered to carry more risk than other types of investments. When the U.S. Targeted Value 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 counterparty, liquidity, interest rate, market, credit and management risks, and the risk of improper valuation. 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.

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 U.S. Targeted Value Portfolio may lose money and there may be a delay in recovering the loaned securities. The U.S. Targeted Value Portfolio could also lose money if it 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.

Cyber Security Risk: The U.S. Targeted Value 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 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 U.S. Targeted Value Portfolio's returns and are meant to provide some indication of the risks of investing in the Portfolio. The bar charts show the changes in the performance of U.S. Targeted Value Portfolio's Class R1 shares and Class R2 shares from year to year. The table illustrates how annualized one year, five year and since inception returns of the Class R1 shares and Class R2 shares compare with those of a broad measure of market performance. The past performance of the U.S. Targeted Value Portfolio is not an indication of future results. Updated performance information for the Portfolio can be obtained by visiting http://us.dimensional.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The bar chart and table immediately following illustrate the variability of the U.S. Targeted Value Portfolio's returns and are meant to provide some indication of the risks of investing in the Portfolio. The bar charts show the changes in the performance of U.S. Targeted Value Portfolio's Class R1 shares and Class R2 shares 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 past performance of the U.S. Targeted Value Portfolio is not an indication of future results.
Bar Chart [Heading] rr_BarChartHeading U.S. Targeted Value Portfolio Class R1 Shares—Total Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock January 2009-December 2017

Highest Quarter    Lowest Quarter
24.44% (7/09–9/09)
    -23.98% (7/11–9/11)
Performance Table Heading rr_PerformanceTableHeading Annualized Returns (%)
Periods ending December 31, 2017
Bar Chart [Heading] didgi_BarChartHeadingOne U.S. Targeted Value Portfolio Class R2 Shares—Total Returns
Bar Chart Closing [TextBlock] didgi_BarChartClosingTextBlockOne January 2009-December 2017

Highest Quarter    Lowest Quarter
24.37% (7/09–9/09)
    -24.03% (7/11–9/11)
Performance Table Heading didgi_PerformanceTableHeadingOne Annualized Returns (%)
Periods ending December 31, 2017
R SHARES | U.S. Targeted Value Portfolio | Class R1  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fee rr_ManagementFeesOverAssets 0.35%
Shareholder Services Fees rr_Component1OtherExpensesOverAssets 0.10% [1]
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Total Other Expenses rr_OtherExpensesOverAssets 0.12%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.47%
1 Year rr_ExpenseExampleYear01 $ 48
3 Years rr_ExpenseExampleYear03 151
5 Years rr_ExpenseExampleYear05 263
10 Years rr_ExpenseExampleYear10 591
1 Year rr_ExpenseExampleNoRedemptionYear01 48
3 Years rr_ExpenseExampleNoRedemptionYear03 151
5 Years rr_ExpenseExampleNoRedemptionYear05 263
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 591
2009 rr_AnnualReturn2009 31.73%
2010 rr_AnnualReturn2010 29.02%
2011 rr_AnnualReturn2011 (6.40%)
2012 rr_AnnualReturn2012 19.06%
2013 rr_AnnualReturn2013 42.95%
2014 rr_AnnualReturn2014 2.89%
2015 rr_AnnualReturn2015 (5.84%)
2016 rr_AnnualReturn2016 26.71%
2017 rr_AnnualReturn2017 9.51%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.44%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (23.98%)
1 Year rr_AverageAnnualReturnYear01 9.51%
5 Years rr_AverageAnnualReturnYear05 13.96%
Since Inception rr_AverageAnnualReturnSinceInception 9.80%
Inception Date rr_AverageAnnualReturnInceptionDate Jan. 31, 2008
R SHARES | U.S. Targeted Value Portfolio | Class R2  
Risk/Return: rr_RiskReturnAbstract  
Shareholder Fees (fees paid directly from your investment) rr_ShareholderFeeOther none
Management Fee rr_ManagementFeesOverAssets 0.35%
Shareholder Services Fees rr_Component1OtherExpensesOverAssets 0.25% [1]
Other Expenses rr_Component2OtherExpensesOverAssets 0.02%
Total Other Expenses rr_OtherExpensesOverAssets 0.27%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.62%
1 Year rr_ExpenseExampleYear01 $ 63
3 Years rr_ExpenseExampleYear03 199
5 Years rr_ExpenseExampleYear05 346
10 Years rr_ExpenseExampleYear10 774
1 Year rr_ExpenseExampleNoRedemptionYear01 63
3 Years rr_ExpenseExampleNoRedemptionYear03 199
5 Years rr_ExpenseExampleNoRedemptionYear05 346
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 774
2009 rr_AnnualReturn2009 31.54%
2010 rr_AnnualReturn2010 28.64%
2011 rr_AnnualReturn2011 (6.48%)
2012 rr_AnnualReturn2012 18.83%
2013 rr_AnnualReturn2013 42.68%
2014 rr_AnnualReturn2014 2.75%
2015 rr_AnnualReturn2015 (5.96%)
2016 rr_AnnualReturn2016 26.49%
2017 rr_AnnualReturn2017 9.32%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel Highest Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Sep. 30, 2009
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 24.37%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel Lowest Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2011
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.03%)
1 Year rr_AverageAnnualReturnYear01 9.32%
5 Years rr_AverageAnnualReturnYear05 13.77%
Since Inception rr_AverageAnnualReturnSinceInception 10.61%
Inception Date rr_AverageAnnualReturnInceptionDate Jun. 30, 2008
R SHARES | U.S. Targeted Value Portfolio | Russell 2000® Value Index (reflects no deduction for fees, expenses, or taxes) | Class R1  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 7.84%
5 Years rr_AverageAnnualReturnYear05 13.01%
Since Inception rr_AverageAnnualReturnSinceInception 8.70%
R SHARES | U.S. Targeted Value Portfolio | Russell 2000® Value Index (reflects no deduction for fees, expenses, or taxes) | Class R2  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 7.84%
5 Years rr_AverageAnnualReturnYear05 13.01%
Since Inception rr_AverageAnnualReturnSinceInception 9.81%
[1] An amount up to 0.10% of the average net assets of the Portfolio’s Class R1 shares and an amount up to 0.25% of the average net assets of the Portfolio’s Class R2 shares may be used to compensate service agents that provide shareholder servicing, record keeping, account maintenance and other services to investors in the Portfolio’s Class R1 shares and Class R2 shares (“Shareholder Services Agent”).