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Label Element Value
T. Rowe Price Institutional Mid-Cap Equity Growth Fund  
Risk/Return: rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading Institutional Mid-Cap Equity Growth Fund
Objective [Heading] rr_ObjectiveHeading Investment Objective(s)
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

The fund seeks to provide long-term capital appreciation by investing in mid-cap stocks with potential for above-average earnings growth.

Expense [Heading] rr_ExpenseHeading Fees and Expenses
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy, hold, and sell shares of the fund. You may also incur brokerage commissions and other charges when buying or selling shares of the fund, which are not reflected in the table or 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)
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock

Portfolio Turnover 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 the fund’s 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 26.1% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 26.10%
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, 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
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

The fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in a diversified portfolio of common stocks of mid-cap companies whose earnings T. Rowe Price expects to grow at a faster rate than the average company. Any derivatives that provide exposure to the investment focus suggested by the fund’s name, or to one or more

market risk factors associated with the investment focus suggested by the fund’s name, are counted (as applicable) toward compliance with the fund’s 80% investment policy.

The fund defines mid-cap companies as those whose market capitalization (number of shares outstanding multiplied by share price) falls within the range of either the S&P MidCap 400® Index or the Russell Midcap® Growth Index. As of December 31, 2024, the market capitalization ranges for the S&P MidCap 400® Index and the Russell Midcap® Growth Index were approximately $2.34 billion to $23.01 billion, and $0.93 billion to $164.92 billion, respectively. The market capitalization of the companies in the indexes change over time and the indexes are periodically reconstituted to ensure that they continue to accurately reflect the mid-cap equity market.

The fund’s growth-oriented approach to stock selection reflects the belief that when a company’s earnings grow faster than both inflation and the overall economy, it will result in a higher stock price.

In selecting investments, the adviser generally favors companies with one or more of the following:

· proven products or services;

· a record of above-average earnings growth;

· demonstrated potential to sustain earnings growth;

· connection to an industry experiencing increasing demand; or

· stock prices that appear to undervalue their growth prospects.

The fund may, to a limited extent, invest in privately held companies and companies that only recently began to trade publicly.

At times, the fund may have a significant portion of its assets invested in the same economic sector.

Risk [Heading] rr_RiskHeading Principal Risks
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following performance information provides some indication of the risks of investing in the fund. The fund’s performance information represents only past performance (before and after taxes) and is not necessarily an indication of future results.

The following bar chart illustrates how much returns can differ from year to year by showing calendar year returns and the best and worst calendar quarter returns during those years for the fund.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information provides some indication of the risks of investing in the fund. The following bar chart illustrates how much returns can differ from year to year by showing calendar year returns and the best and worst calendar quarter returns during those years for the fund. The following table shows the average annual total returns for the fund. The fund’s performance information included in the table is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the table may also include one or more indexes that more closely aligns to the fund’s investment strategy (Strategy Benchmark(s)).
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress troweprice.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture The fund’s performance information represents only past performance (before and after taxes) and is not necessarily an indication of future results.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Returns
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock
         
  

Quarter Ended

Total

Return

  

Quarter Ended

Total

Return

 
 

Best Quarter

6/30/20

28.62%

 

Worst Quarter

3/31/20

-24.14%

 
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns Periods ended December 31, 2024
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 an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as a 401(k) account or an IRA.
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock

The following table shows the average annual total returns for the fund. The fund’s performance information included in the table is compared with a regulatory required index that represents an overall securities market (Regulatory Benchmark). In addition, the table may also include one or more indexes that more closely aligns to the fund’s investment strategy (Strategy Benchmark(s)).

In addition, the table shows hypothetical after-tax returns to demonstrate how taxes paid by a shareholder may influence returns. 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 an investor’s tax situation and may differ from those shown. After-tax returns shown are not relevant to investors who hold their fund shares through tax-deferred arrangements, such as a 401(k) account or an IRA.

Performance Table Closing [Text Block] rr_PerformanceTableClosingTextBlock Updated performance information is available through troweprice.com.
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Risk Lose Money [Member]  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock The fund’s share price fluctuates, which means you could lose money by investing in the fund.
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Mid-cap stocks  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Mid-cap stocks: Investments in securities issued by mid-cap companies are likely to be more volatile than investments in securities issued by large-cap companies. Mid-cap companies may have less seasoned management, narrower product lines, and less capital reserves and liquidity than large-cap companies, and are therefore more sensitive to economic, market, and industry changes.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Growth investing  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Growth investing: The fund’s growth approach to investing could cause it to underperform other stock funds that employ a different investment style. Growth stocks tend to be more volatile than certain other types of stocks and their prices may fluctuate more dramatically than the overall stock market. A stock with growth characteristics can have sharp price declines due to

decreases in current or expected earnings and may lack dividends that can help cushion its share price in a declining market.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Stock investing  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Stock investing: Stocks generally fluctuate in value more than bonds and may decline significantly over short time periods. There is a chance that stock prices overall will decline because stock markets tend to move in cycles, with periods of rising and falling prices. The value of stocks held by the fund may decline due to general weakness or volatility in the stock markets in which the fund invests or because of factors that affect a particular company or industry.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Market conditions  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Market conditions: The value of the fund’s investments may decrease, sometimes rapidly or unexpectedly, due to factors affecting an issuer held by the fund, particular industries, or the overall securities markets. A variety of factors can increase the volatility of the fund’s holdings and markets generally, including economic, political, or regulatory developments, recessions, inflation, rapid interest rate changes, war, military conflict, acts of terrorism, natural disasters, and outbreaks of infectious illnesses or other widespread public health issues (such as the coronavirus pandemic) and related governmental and public responses (including sanctions). Certain events may cause instability across global markets, including reduced liquidity and disruptions in trading markets, while some events may affect certain geographic regions, countries, sectors, and industries more significantly than others. Government intervention in markets may impact interest rates, market volatility, and security pricing. These adverse developments may cause broad declines in market value due to short-term market movements or for significantly longer periods during more prolonged market downturns.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Sector exposure  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Sector exposure: Issuers in the same economic sector may be similarly affected by economic or market events, making the fund more vulnerable to unfavorable developments in that economic sector than funds that invest more broadly.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Private placements and IPOs  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Private placements and IPOs: Investments in the stocks of privately held companies and in companies that only recently began to publicly trade, such as initial public offerings or IPOs, involve greater risks than investments in stocks of companies that have traded publicly on an exchange for extended time periods. There is significantly less information available about these companies’ business models, quality of management, earnings growth potential, and other criteria that are normally considered when evaluating the investment prospects of a company. Private placements and other restricted securities held by the fund are typically considered to be illiquid and tend to be difficult to value since there are no market prices and less overall financial information available. The adviser evaluates a variety of factors when assigning a value to these holdings, but the determination involves some degree of subjectivity and the value assigned for the fund may differ from the value assigned by other mutual funds holding the same security.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Liquidity  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Liquidity: A particular investment or an entire market segment may become less liquid or even illiquid, sometimes abruptly, which could limit the fund’s ability to purchase or sell holdings in a timely manner at a desired price. An inability to sell a portfolio holding can adversely affect the fund’s overall value or prevent the fund from being able to take advantage of other investment opportunities. Liquidity risk may be magnified during periods of substantial market volatility and unexpected episodes of illiquidity may limit the fund’s ability to pay redemption proceeds without

selling holdings at an unfavorable time or at a suitable price. Large redemptions may also have a negative impact on the fund’s overall liquidity.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Active management  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Active management: The fund’s overall investment program and holdings selected by the fund’s investment adviser may underperform the broad markets, relevant indices, or other funds with similar objectives and investment strategies.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Cybersecurity breaches  
Risk/Return: rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock

Cybersecurity breaches: The fund could be harmed by intentional cyberattacks and other cybersecurity breaches, including unauthorized access to the fund’s assets, confidential information, or other proprietary information. In addition, a cybersecurity breach could cause one of the fund’s service providers or financial intermediaries to suffer unauthorized data access, data corruption, or loss of operational functionality.

T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Russell 3000® Index  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Russell 3000® Index [1]
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Russell 3000® Index  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Label rr_AverageAnnualReturnLabel Russell 3000® Index
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Russell 3000® Index  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 23.81%
5 Years rr_AverageAnnualReturnYear05 13.86%
10 Years rr_AverageAnnualReturnYear10 12.55%
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Russell Midcap® Growth Index  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes [Text] rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses, or taxes)
Label rr_AverageAnnualReturnLabel Russell Midcap® Growth Index
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Russell Midcap® Growth Index  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 22.10%
5 Years rr_AverageAnnualReturnYear05 11.47%
10 Years rr_AverageAnnualReturnYear10 11.54%
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Lipper Mid-Cap Growth Funds Index  
Risk/Return: rr_RiskReturnAbstract  
Label rr_AverageAnnualReturnLabel Lipper Mid-Cap Growth Funds Index
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Lipper Mid-Cap Growth Funds Index  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 10.73%
5 Years rr_AverageAnnualReturnYear05 7.38%
10 Years rr_AverageAnnualReturnYear10 9.34%
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Institutional Mid-Cap Equity Growth Fund  
Risk/Return: rr_RiskReturnAbstract  
Management fees rr_ManagementFeesOverAssets 0.60%
Other expenses rr_OtherExpensesOverAssets 0.01%
Total annual fund operating expenses rr_ExpensesOverAssets 0.61%
1 Year rr_ExpenseExampleYear01 $ 62
3 Years rr_ExpenseExampleYear03 195
5 Years rr_ExpenseExampleYear05 340
10 Years rr_ExpenseExampleYear10 $ 762
Annual Return 2015 rr_AnnualReturn2015 6.94%
Annual Return 2016 rr_AnnualReturn2016 6.94%
Annual Return 2017 rr_AnnualReturn2017 26.02%
Annual Return 2018 rr_AnnualReturn2018 (2.23%)
Annual Return 2019 rr_AnnualReturn2019 33.09%
Annual Return 2020 rr_AnnualReturn2020 23.87%
Annual Return 2021 rr_AnnualReturn2021 15.52%
Annual Return 2022 rr_AnnualReturn2022 (23.17%)
Annual Return 2023 rr_AnnualReturn2023 20.62%
Annual Return 2024 rr_AnnualReturn2024 9.67%
Label rr_HighestQuarterlyReturnLabel Best Quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Jun. 30, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 28.62%
Label rr_LowestQuarterlyReturnLabel Worst Quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (24.14%)
1 Year rr_AverageAnnualReturnYear01 9.67%
5 Years rr_AverageAnnualReturnYear05 7.78%
10 Years rr_AverageAnnualReturnYear10 10.55%
Inception Date rr_AverageAnnualReturnInceptionDate Jul. 31, 1996
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Institutional Mid-Cap Equity Growth Fund | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 6.44%
5 Years rr_AverageAnnualReturnYear05 5.88%
10 Years rr_AverageAnnualReturnYear10 8.85%
T. Rowe Price Institutional Mid-Cap Equity Growth Fund | Institutional Mid-Cap Equity Growth Fund | After Taxes on Distributions and Sales  
Risk/Return: rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 8.04%
5 Years rr_AverageAnnualReturnYear05 6.02%
10 Years rr_AverageAnnualReturnYear10 8.38%
[1] Due to new SEC Rules on shareholder reporting, the fund adopted a new broad-based securities market index, referred to as the Regulatory Benchmark.