v3.24.1.u1
Label Element Value
Prospectus [Line Items] rr_ProspectusLineItems  
Document Type dei_DocumentType 485BPOS
Document Period End Date dei_DocumentPeriodEndDate Dec. 31, 2023
Entity Registrant Name dei_EntityRegistrantName ROYCE CAPITAL FUND
Entity Central Index Key dei_EntityCentralIndexKey 0001006387
Entity Inv Company Type dei_EntityInvCompanyType N-1A
Amendment Flag dei_AmendmentFlag false
Document Creation Date dei_DocumentCreationDate May 01, 2024
Document Effective Date dei_DocumentEffectiveDate May 01, 2024
Prospectus Date rr_ProspectusDate May 01, 2024
Royce Micro-Cap Portfolio  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Royce Micro-Cap Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Royce Micro-Cap Portfolio's investment goal is long-term growth of capital.

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

The following table presents the fees and expenses that you may pay if you buy and hold shares of the Fund. The table does not include variable contract or other potential charges. Because variable contract or other potential charges are not included, the total fees and expenses that you will incur will be higher than the fees and expenses set forth in the table. See your variable contract prospectus for more information about variable contract charges.

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 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. These costs, which are not reflected in total 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 24% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 24.00%
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 total operating expenses remain the same. Although your actual costs may be higher or lower, based on the assumptions your costs would be:

Strategy [Heading] rr_StrategyHeading Principal Investment Strategy
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Royce Investment Partners (“Royce”), the Fund’s investment adviser, invests the Fund’s assets primarily in equity securities of micro-cap companies. Micro-cap companies are those that have a market capitalization not greater than that of the largest company in the Russell Microcap® Index at the time of its most recent reconstitution. Royce uses multiple investment themes and offers wide exposure to micro-cap stocks by investing in companies with strong fundamentals and/or prospects selling at prices that Royce believes do not fully reflect these attributes. Royce considers companies with strong balance sheets, attractive growth prospects, and/or the potential for improvement in cash flow levels and internal rates of return, among other factors. 

The Fund invests at least 80% of its net assets in equity securities of micro-cap companies, under normal circumstances. Although the Fund generally focuses on securities of U.S. companies, it may invest up to 25% of its net assets (measured at the time of investment) in securities of companies headquartered in foreign countries. The Fund may invest in other investment companies that invest primarily in equity securities. The Fund may sell securities to, among other things, secure gains, limit losses, redeploy assets into what Royce deems to be more promising opportunities, and/or manage cash levels in the Fund’s portfolio.

Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Fund invests at least 80% of its net assets in equity securities of micro-cap companies, under normal circumstances. Although the Fund generally focuses on securities of U.S. companies, it may invest up to 25% of its net assets (measured at the time of investment) in securities of companies headquartered in foreign countries. The Fund may invest in other investment companies that invest primarily in equity securities. The Fund may sell securities to, among other things, secure gains, limit losses, redeploy assets into what Royce deems to be more promising opportunities, and/or manage cash levels in the Fund’s portfolio.
Risk [Heading] rr_RiskHeading Primary Risks for Fund Investors
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following performance information provides an indication of the risks investing in the Fund. Past performance does not indicate how the Fund will perform in the future. The Calendar Year Total Returns chart shows performance year-by-year over the last ten years (Investment Class used for illustrative purposes—returns differ by Class). The Average Annual Total Returns table shows how the Fund's average annual total returns for various periods compare with those of the Russell Microcap Index, the Fund's primary benchmark index, and the Russell 2000 Index, the Fund's secondary benchmark index. The Classes have substantially similar returns because they invest in the same portfolio of securities, differing only to the extent that the Service Class has higher expenses than the Investment Class. If Service Class's expenses had been reflected, returns for that Class would have been lower.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information provides an indication of the risks investing in the Fund.
Performance Availability Phone [Text] rr_PerformanceAvailabilityPhone (800) 841-1180
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress www.royceinvest.com
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Past performance does not indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns Investment Class(%)
Bar Chart Does Not Reflect Sales Loads [Text] rr_BarChartDoesNotReflectSalesLoads The Fund's total returns do not reflect any deduction for charges or expenses of the variable contracts investing in the Fund. If these costs and expenses were reflected, the returns shown would be lower.
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

During the period shown in the bar chart, the highest return for a calendar quarter was 35.62% (quarter ended 12/31/20) and the lowest return for a calendar quarter was -31.90% (quarter ended 3/31/20).

Performance Table Narrative rr_PerformanceTableNarrativeTextBlock

The Fund's total returns do not reflect any deduction for charges or expenses of the variable contracts investing in the Fund. If these costs and expenses were reflected, the returns shown would be lower. Current month-end performance information for all share classes may be obtained at www.royceinvest.com or by calling Shareholder Services at (800) 841-1180.

Average Annual Return, Caption rr_AverageAnnualReturnCaption Average Annual Total Returns As of 12/31/23 (%)
Royce Micro-Cap Portfolio | Russell Microcap Index (Reflects no deductions for fees, expenses, or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 9.33%
5 Years rr_AverageAnnualReturnYear05 8.56%
10 Years rr_AverageAnnualReturnYear10 5.79%
Royce Micro-Cap Portfolio | Russell 2000 Index (Reflects no deductions for fees, expenses, or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 16.93%
5 Years rr_AverageAnnualReturnYear05 9.97%
10 Years rr_AverageAnnualReturnYear10 7.16%
Royce Micro-Cap Portfolio | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

As with any mutual fund that invests in common stocks, Royce Micro-Cap Portfolio is subject to market risk—the possibility that common stock prices will decline over short and/or extended periods of time due to overall market, financial, and economic conditions, trends, or events, governmental or central bank actions and/or interventions, changes in investor sentiment, armed conflicts, economic sanctions and countermeasures in response to sanctions, market disruptions caused by trade disputes or other factors, political developments, major cybersecurity events and acts of terrorism, the global and domestic effects of a pandemic or epidemic, contagion effects on the finance sector and the overall economy from banking industry instability, and other factors that may or may not be directly related to the issuer of a security held by the Fund. Economies and financial markets throughout the world are increasingly interconnected, and economic, financial, or political events in one country or region could have profound impacts on global economies or markets. Armed conflicts in Europe and the Middle East, as well as any recent banking industry instability, may adversely affect global economies, markets, industries, and individual companies in ways that cannot necessarily be foreseen. As a result, the value of your investment in the Fund will fluctuate, sometimes sharply and unpredictably, and you could lose money over short and/or long periods of time.

Royce Micro-Cap Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock As a result, the value of your investment in the Fund will fluctuate, sometimes sharply and unpredictably, and you could lose money over short and/or long periods of time.
Royce Micro-Cap Portfolio | Microcap Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

The prices of micro-cap securities are generally more volatile than those of larger-cap securities. In addition, because micro-cap securities tend to have significantly lower trading volumes than larger-cap securities, the Fund may have difficulty selling holdings or may only be able to sell holdings at prices substantially lower than what Royce believes they are worth. Therefore, the Fund may involve considerably more risk of loss and its returns may differ significantly from funds investing in larger-cap companies or other asset classes.

Royce Micro-Cap Portfolio | Sector Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

A significant portion of the Fund’s assets may, from time to time, be invested in companies from a single sector or a limited number of sectors. Such an investment approach may involve considerably more risk to investors than one that is more broadly diversified across economic sectors because it may be more susceptible to corporate, economic, political, regulatory, or market events that adversely affect the relevant sector(s). As of December 31, 2023, the Fund invested a significant portion of its assets in companies from the Information Technology and Industrials sectors. Information Technology sector companies can be significantly affected by obsolescence of existing technology, short product cycles, falling prices and profits, competition from new market entrants, and general economic conditions. In addition, companies from the Industrials sector can be significantly affected by general economic trends, commodity prices, legislation, government regulation and spending, import and export controls, worldwide competition, changes in consumer sentiment and spending, and liability for environmental damage, depletion of resources, and mandated expenditures for safety and pollution control.

Royce Micro-Cap Portfolio | Foreign Investment Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Investment in foreign securities involves risks that may not be encountered in U.S. investments, including adverse political, social, economic, environmental, public health, and/or other developments that are unique to a particular region or country. Prices of foreign securities in particular countries or regions may, at times, move in a different direction and/or be more volatile than those of U.S. securities. Because the Fund does not intend to hedge its foreign currency exposure, the U.S. dollar value of the Fund’s investments may be harmed by declines in the value of foreign currencies in relation to the U.S. dollar.

Royce Micro-Cap Portfolio | Allocation Adjustment Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Allocation adjustment programs–used by certain participating insurance companies to help manage the volatility of the relevant variable contract investment options and to preserve variable contract value–may result in transfers of assets among the relevant investment options, including the Fund. These programs may result in large-scale asset flows into and out of the Fund, which could adversely affect the Fund, including its risk profile, expenses, and performance. For example, these asset flows may adversely affect performance by requiring the Fund to purchase or sell securities at inopportune times, by otherwise limiting Royce’s ability to fully implement the Fund’s investment strategies, or by requiring the Fund to hold a larger portion of its assets in cash or highly liquid securities than it otherwise would hold. Such asset flows may also result in higher portfolio turnover rates, increased payments of brokerage commissions, lower asset levels, and higher operating expense ratios for the Fund. The Fund’s portfolio turnover rate for the fiscal year ended December 31, 2023, was 24% of the average value of its portfolio.

Royce Micro-Cap Portfolio | Underperformance Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Royce’s estimate of a company’s current worth may prove to be inaccurate, or this estimate may not be recognized by other investors, which could lead to portfolio losses or underperformance relative to similar funds and/or the Fund’s benchmark indexes. Securities in the Fund’s portfolio may not increase as much as the market as a whole and some securities may continue to be undervalued for long periods of time or may never reach what Royce believes are their full market values.

Royce Micro-Cap Portfolio | Risk Not Insured [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Investments in the Fund are not bank deposits and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. This Prospectus is not a contract.

Royce Micro-Cap Portfolio | Cybersecurity Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Cybersecurity incidents may allow an unauthorized party to gain access to Fund assets, Fund or investor data, or proprietary information. Such incidents may also cause the Fund, Royce, and/or their service providers to suffer data breaches, data corruption, or loss of operational functionality. In addition, cybersecurity incidents may also prevent Fund investors from purchasing, redeeming, or exchanging shares, as well as from receiving distributions. The Fund and Royce have limited ability to prevent or mitigate cybersecurity incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or Royce. Cybersecurity incidents may result in significant financial losses to the Fund and its shareholders, and substantial costs may be incurred in order to prevent any future cybersecurity incidents. Issuers of securities in which the Fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers are affected by cybersecurity incidents.

Royce Micro-Cap Portfolio | Investment Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol RCMCX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.00%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.18%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.18%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 120
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 375
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 649
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,432
Annual Return 2014 rr_AnnualReturn2014 (3.60%)
Annual Return 2015 rr_AnnualReturn2015 (12.50%)
Annual Return 2016 rr_AnnualReturn2016 19.70%
Annual Return 2017 rr_AnnualReturn2017 5.20%
Annual Return 2018 rr_AnnualReturn2018 (9.00%)
Annual Return 2019 rr_AnnualReturn2019 19.60%
Annual Return 2020 rr_AnnualReturn2020 23.80%
Annual Return 2021 rr_AnnualReturn2021 30.00%
Annual Return 2022 rr_AnnualReturn2022 (22.40%)
Annual Return 2023 rr_AnnualReturn2023 18.80%
1 Year rr_AverageAnnualReturnYear01 18.78%
5 Years rr_AverageAnnualReturnYear05 12.13%
10 Years rr_AverageAnnualReturnYear10 5.53%
Royce Micro-Cap Portfolio | Service Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol RCMSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.00%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses (as a percentage of Assets): rr_OtherExpensesOverAssets 0.21%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.46%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 149
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 462
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 797
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,746
1 Year rr_AverageAnnualReturnYear01 18.56%
5 Years rr_AverageAnnualReturnYear05 11.84%
10 Years rr_AverageAnnualReturnYear10 5.28%
Royce Small-Cap Portfolio  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk/Return [Heading] rr_RiskReturnHeading Royce Small-Cap Portfolio
Objective [Heading] rr_ObjectiveHeading Investment Goal
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock

Royce Small-Cap Portfolio’s investment goal is long-term growth of capital.

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

The following table presents the fees and expenses that you may pay if you buy and hold shares of the Fund. The table does not include variable contract or other potential charges. Because variable contract or other potential charges are not included, the total fees and expenses that you will incur will be higher than the fees and expenses set forth in the table. See your variable contract prospectus for more information about variable contract charges.

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 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. These costs, which are not reflected in total 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 69% of the average value of its portfolio.

Portfolio Turnover, Rate rr_PortfolioTurnoverRate 69.00%
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 total operating expenses remain the same. Although your actual costs may be higher or lower, based on the assumptions your costs would be:

Strategy [Heading] rr_StrategyHeading Principal Investment Strategy
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock

Royce Investment Partners (“Royce”), the Fund’s investment adviser, invests the Fund’s assets primarily in equity securities of small-cap companies that Royce believes are trading below its estimate of their current worth. Small-cap companies are those that have a market capitalization not greater than that of the largest company in the Russell 2000® Index at the time of its most recent reconstitution. The Fund generally invests in such companies that Royce believes also possess financial strength, a strong business model, and the ability to generate and effectively allocate excess free cash flow.

The Fund invests at least 80% of its net assets in equity securities of small-cap companies, under normal circumstances. Although the Fund generally focuses on securities of U.S. companies, it may invest up to 25% of its net assets (measured at the time of investment) in securities of companies headquartered in foreign countries. The Fund may invest in other investment companies that invest primarily in equity securities. The Fund may sell securities to, among other things, secure gains, limit losses, redeploy assets into what Royce deems to be more promising opportunities, and/or manage cash levels in the Fund’s portfolio.

Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration The Fund invests at least 80% of its net assets in equity securities of small-cap companies, under normal circumstances. Although the Fund generally focuses on securities of U.S. companies, it may invest up to 25% of its net assets (measured at the time of investment) in securities of companies headquartered in foreign countries. The Fund may invest in other investment companies that invest primarily in equity securities. The Fund may sell securities to, among other things, secure gains, limit losses, redeploy assets into what Royce deems to be more promising opportunities, and/or manage cash levels in the Fund’s portfolio.
Risk [Heading] rr_RiskHeading Primary Risks for Fund Investors
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading Performance
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock

The following performance information provides an indication of the risks of investing in the Fund. Past performance does not indicate how the Fund will perform in the future. The Calendar Year Total Returns chart shows performance year-by-year over the last ten years (Investment Class used for illustrative purposes—returns differ by Class). The Average Annual Total Returns table shows how the Fund’s average annual total returns for various periods compare with those of the Russell 2000 Value Index, the Fund’s primary benchmark index, and the Russell 2000 Index, the Fund’s secondary benchmark index. Each Class has substantially similar returns because they invest in the same portfolio of securities, differing only to the extent that the Service Class has higher expenses than the Investment Class. If Service Class’s expenses had been reflected, returns for that Class would have been lower.

Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns The following performance information provides an indication of the risks of investing in the Fund.
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture Past performance does not indicate how the Fund will perform in the future.
Bar Chart [Heading] rr_BarChartHeading Calendar Year Total Returns Investment Class (%)  
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock

During the period shown in the bar chart, the highest return for a calendar quarter was 26.53% (quarter ended 12/31/20) and the lowest return for a calendar quarter was -39.32% (quarter ended 3/31/20).

Performance Table Heading rr_PerformanceTableHeading Average Annual Total Returns As of 12/31/23 (%)
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock

The Fund’s total returns do not reflect any deduction for charges or expenses of the variable contracts investing in the Fund. If these costs and expenses were reflected, the returns shown would be lower. Current month-end performance information for all share classes may be obtained at www.royceinvest.com or by calling Shareholder Services at (800) 841-1180.

Royce Small-Cap Portfolio | Russell 2000 Value Index (Reflects no deductions for fees, expenses, or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 14.65%
5 Years rr_AverageAnnualReturnYear05 10.00%
10 Years rr_AverageAnnualReturnYear10 6.76%
Royce Small-Cap Portfolio | Russell 2000 Index (Reflects no deductions for fees, expenses, or taxes)  
Prospectus [Line Items] rr_ProspectusLineItems  
1 Year rr_AverageAnnualReturnYear01 16.93%
5 Years rr_AverageAnnualReturnYear05 9.97%
10 Years rr_AverageAnnualReturnYear10 7.16%
Royce Small-Cap Portfolio | Market Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

As with any mutual fund that invests in common stocks, Royce Small-Cap Portfolio is subject to market risk—the possibility that common stock prices will decline over short and/or extended periods of time due to overall market, financial, and economic conditions, trends, or events, governmental or central bank actions or interventions, changes in investor sentiment, armed conflicts, economic sanctions and countermeasures in response to sanctions, market disruptions caused by trade disputes or other factors, political developments, major cybersecurity events and acts of terrorism, the global and domestic effects of a pandemic or epidemic, contagion effects on the finance sector and the overall economy from banking industry instability, and other factors that may or may not be directly related to the issuer of a security held by the Fund. Economies and financial markets throughout the world are increasingly interconnected, and economic, financial, or political events in one country or region could have profound impacts on global economies or markets. Armed conflicts in Europe and the Middle East, as well as any recent banking industry instability, may adversely affect global economies, markets, industries, and individual companies in ways that cannot necessarily be foreseen. As a result, the value of your investment in the Fund will fluctuate, sometimes sharply and unpredictably, and you could lose money over short and/or long periods of time.

Royce Small-Cap Portfolio | Risk Lose Money [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock As a result, the value of your investment in the Fund will fluctuate, sometimes sharply and unpredictably, and you could lose money over short and/or long periods of time.
Royce Small-Cap Portfolio | Sector Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

As of December 31, 2023, the Fund invested a significant portion of its assets in a limited number of issuers. Such a portfolio may involve considerably more risk to investors than one that invests in a larger number of issuers because such a portfolio may be more susceptible to any single corporate, economic, political, regulatory, or market event.

A significant portion of the Fund’s assets also may, from time to time, be invested in companies from a single sector or a limited number of sectors. Such an investment approach may involve considerably more risk to investors than one that is more broadly diversified across economic sectors because it may be more susceptible to corporate, economic, political, regulatory, or market events that adversely affect the relevant sector(s). As of December 31, 2023, the Fund invested a significant portion of its assets in companies from the Consumer Discretionary sector. These companies can be significantly affected by the performance of the overall economy, particularly the level of consumer inflation, interest rates, competition, consumer confidence and spending, and changes in demographics and consumer tastes.

Royce Small-Cap Portfolio | Foreign Investment Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Investment in foreign securities involves risks that may not be encountered in U.S. investments, including adverse political, social, economic, environmental, public health, and/or other developments that are unique to a particular region or country. Prices of foreign securities in particular countries or regions may, at times, move in a different direction and/or be more volatile than those of U.S. securities. Because the Fund does not intend to hedge its foreign currency exposure, the U.S. dollar value of the Fund’s investments may be harmed by declines in the value of foreign currencies in relation to the U.S. dollar.

Royce Small-Cap Portfolio | Allocation Adjustment Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Allocation adjustment programs–used by certain participating insurance companies to help manage the volatility of the relevant variable contract investment options and to preserve variable contract value–may result in transfers of assets among the relevant investment options, including the Fund. These programs may result in large-scale asset flows into and out of the Fund, which could adversely affect the Fund, including its risk profile, expenses, and performance. For example, these asset flows may adversely affect performance by requiring the Fund to purchase or sell securities at inopportune times, by otherwise limiting Royce’s ability to fully implement the Fund’s investment strategies, or by requiring the Fund to hold a larger portion of its assets in cash or highly liquid securities than it otherwise would hold. Such asset flows may also result in higher portfolio turnover rates, increased payments of brokerage commissions, lower asset levels, and higher operating expense ratios for the Fund. The Fund’s portfolio turnover rate for the fiscal year ended December 31, 2023, was 69% of the average value of its portfolio.

Royce Small-Cap Portfolio | Underperformance Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Royce’s estimate of a company’s current worth may prove to be inaccurate, or this estimate may not be recognized by other investors, which could lead to portfolio losses or underperformance relative to similar funds and/or the Fund’s benchmark indexes. Additionally, “value” stocks may remain undervalued for long periods (particularly during times of low or declining interest rates), undervaluation may become more severe, or perceived undervaluation may actually represent intrinsic value. Securities in the Fund’s portfolio may not increase as much as the market as a whole and some securities may continue to be undervalued for long periods of time or may never reach what Royce believes are their full market values.

Royce Small-Cap Portfolio | Risk Not Insured [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Investments in the Fund are not bank deposits and are not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. This Prospectus is not a contract.

Royce Small-Cap Portfolio | Cybersecurity Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

Cybersecurity incidents may allow an unauthorized party to gain access to Fund assets, Fund or investor data, or proprietary information. Such incidents may also cause the Fund, Royce, and/or their service providers to suffer data breaches, data corruption, or loss of operational functionality. In addition, cybersecurity incidents may also prevent Fund investors from purchasing, redeeming, or exchanging shares, as well as from receiving distributions. The Fund and Royce have limited ability to prevent or mitigate cybersecurity incidents affecting third-party service providers, and such third-party service providers may have limited indemnification obligations to the Fund or Royce. Cybersecurity incidents may result in significant financial losses to the Fund and its shareholders, and substantial costs may be incurred in order to prevent any future cybersecurity incidents. Issuers of securities in which the Fund invests are also subject to cybersecurity risks, and the value of these securities could decline if the issuers are affected by cybersecurity incidents.

Royce Small-Cap Portfolio | Smallcap Risk [Member]  
Prospectus [Line Items] rr_ProspectusLineItems  
Risk [Text Block] rr_RiskTextBlock

The prices of small-cap securities are generally more volatile than those of larger-cap securities. In addition, because small-cap securities tend to have significantly lower trading volumes than larger-cap securities, the Fund may have difficulty selling holdings or may only be able to sell holdings at prices substantially lower than what Royce believes they are worth. Therefore, the Fund may involve considerably more risk of loss and its returns may differ significantly from funds investing in larger-cap companies or other asset classes.

Royce Small-Cap Portfolio | Investment Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol RCPFX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.00%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Component3 Other Expenses rr_Component3OtherExpensesOverAssets 0.15%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.15%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 117
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 365
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 633
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,398
Annual Return 2014 rr_AnnualReturn2014 3.20%
Annual Return 2015 rr_AnnualReturn2015 (11.80%)
Annual Return 2016 rr_AnnualReturn2016 21.00%
Annual Return 2017 rr_AnnualReturn2017 5.40%
Annual Return 2018 rr_AnnualReturn2018 (8.30%)
Annual Return 2019 rr_AnnualReturn2019 18.70%
Annual Return 2020 rr_AnnualReturn2020 (7.20%)
Annual Return 2021 rr_AnnualReturn2021 28.80%
Annual Return 2022 rr_AnnualReturn2022 (9.20%)
Annual Return 2023 rr_AnnualReturn2023 25.90%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel highest return for a calendar quarter
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2020
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 26.53%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel lowest return for a calendar quarter
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Mar. 31, 2020
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (39.32%)
1 Year rr_AverageAnnualReturnYear01 25.93%
5 Years rr_AverageAnnualReturnYear05 10.17%
10 Years rr_AverageAnnualReturnYear10 5.61%
Royce Small-Cap Portfolio | Service Class  
Prospectus [Line Items] rr_ProspectusLineItems  
Trading Symbol dei_TradingSymbol RCSSX
Maximum Sales Charge Imposed on Purchases (as a percentage of Offering Price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (as a percentage of Offering Price) rr_MaximumDeferredSalesChargeOverOfferingPrice none
Maximum Sales Charge on Reinvested Dividends and Distributions (as a percentage) rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther none
Management Fees (as a percentage of Assets) rr_ManagementFeesOverAssets 1.00%
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Component3 Other Expenses rr_Component3OtherExpensesOverAssets 0.14%
Expenses (as a percentage of Assets) rr_ExpensesOverAssets 1.39%
Expense Example, with Redemption, 1 Year rr_ExpenseExampleYear01 $ 142
Expense Example, with Redemption, 3 Years rr_ExpenseExampleYear03 440
Expense Example, with Redemption, 5 Years rr_ExpenseExampleYear05 761
Expense Example, with Redemption, 10 Years rr_ExpenseExampleYear10 $ 1,669
1 Year rr_AverageAnnualReturnYear01 25.53%
5 Years rr_AverageAnnualReturnYear05 9.90%
10 Years rr_AverageAnnualReturnYear10 5.35%