| Form N-CSR Cover | 6 Months Ended |
| Jun. 30, 2024 | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | ROYCE CAPITAL FUND |
| Entity Central Index Key | 0001006387 |
| Document Period End Date | Jun. 30, 2024 |
| Shareholder Report | 6 Months Ended |
| Jun. 30, 2024 USD ($) shares | |
| Shareholder Report [Line Items] | |
| Document Type | N-CSRS |
| Amendment Flag | false |
| Registrant Name | ROYCE CAPITAL FUND |
| Entity Central Index Key | 0001006387 |
| Document Period End Date | Jun. 30, 2024 |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | |
| Shareholder Report [Line Items] | |
| Fund Name | Royce Capital Fund—Micro-Cap Portfolio |
| Class Name | Investment Class |
| Trading Symbol | RCMCX |
| Annual or Semi-Annual Statement [Text Block] | Semiannual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | semi annual shareholder report |
| Additional Information [Text Block] | Additional information is available at www.royceinvest.com/literature, including its: • Prospectus • Financial Information • Fund Holdings • Proxy Voting Information |
| Material Fund Change Notice [Text Block] | Householding We will deliver a single copy of prospectuses, proxies, financial reports, and other communication to shareholders with the same residential address, provided they have the same last name or we reasonably believe them to be members of the same family. Unless we are notified otherwise, we will continue to send you only one copy of these materials for as long as you remain a shareholder of the Fund. If you would like to receive individual mailings, please call 1-800-221-4268. Please allow 30 days for your request to be processed. Shareholders may also elect to receive these reports electronically. Please go to www.royceinvest.com for more details. |
| Additional Information Phone Number | 1-800-221-4268. |
| Additional Information Website | www.royceinvest.com/literature. |
| Expenses [Text Block] | What Were the Fund Costs for the Last Six-Months? Based on a hypothetical $10,000 investment COSTS OF A COSTS PAID AS A PERCENTAGE FUND/CLASS $10,000 INVESTMENT OF A $10,000 INVESTMENT¹ Royce Capital Fund—Micro-Cap Portfolio—Investment Class $60 1.18% ¹Annualized |
| Expenses Paid, Amount | $ 60 |
| Expense Ratio, Percent | 1.18% |
| Factors Affecting Performance [Text Block] | Important Information Sector weightings are determined using the Global Industry Classification Standard (“GICS”). GICS was developed by, and is the exclusive property of, Standard & Poor’s Financial Services LLC (“S&P”) and MSCI Inc. (“MSCI”). GICS is the trademark of S&P and MSCI. “Global Industry Classification Standard (GICS)” and “GICS Direct” are service marks of S&P and MSCI. Distributor: Royce Fund Services, LLC. |
| Line Graph [Table Text Block] | What Did The Fund Invest In? Representing percentage of total net assets of the Fund as of 6/30/24 (%) Top 10 Positions Portfolio Sector Breakdown CECO Environmental 1.6 Artivion 1.4 Newpark Resources 1.4 Graham Corporation 1.3 American Superconductor 1.3 VSE Corporation 1.3 QuinStreet 1.3 Shoe Carnival 1.3 CRA International 1.3 Arlo Technologies 1.3 |
| Net Assets | $ 132 |
| Holdings Count | shares | 123 |
| Investment Company, Portfolio Turnover | 11% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics As of 6/30/24 Fund Size (Millions) $ 132 Number of Holdings 123 Turnover Rate 11 |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | |
| Shareholder Report [Line Items] | |
| Fund Name | Royce Capital Fund—Micro-Cap Portfolio |
| Class Name | Service Class |
| Trading Symbol | RCMSX |
| Annual or Semi-Annual Statement [Text Block] | Semiannual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | semi annual shareholder report |
| Additional Information [Text Block] | Additional information is available at www.royceinvest.com/literature, including its: • Prospectus • Financial Information • Fund Holdings • Proxy Voting Information |
| Material Fund Change Notice [Text Block] | Householding We will deliver a single copy of prospectuses, proxies, financial reports, and other communication to shareholders with the same residential address, provided they have the same last name or we reasonably believe them to be members of the same family. Unless we are notified otherwise, we will continue to send you only one copy of these materials for as long as you remain a shareholder of the Fund. If you would like to receive individual mailings, please call 1-800-221-4268. Please allow 30 days for your request to be processed. Shareholders may also elect to receive these reports electronically. Please go to www.royceinvest.com for more details. |
| Additional Information Phone Number | 1-800-221-4268 |
| Additional Information Website | www.royceinvest.com/literature |
| Expenses [Text Block] | Based on a hypothetical $10,000 investment COSTS OF A COSTS PAID AS A PERCENTAGE FUND/CLASS $10,000 INVESTMENT OF A $10,000 INVESTMENT¹ Royce Capital Fund—Micro-Cap Portfolio—Service Class $73 1.45% ¹Annualized |
| Expenses Paid, Amount | $ 73 |
| Expense Ratio, Percent | 1.45% |
| Factors Affecting Performance [Text Block] | Important Information Sector weightings are determined using the Global Industry Classification Standard (“GICS”). GICS was developed by, and is the exclusive property of, Standard & Poor’s Financial Services LLC (“S&P”) and MSCI Inc. (“MSCI”). GICS is the trademark of S&P and MSCI. “Global Industry Classification Standard (GICS)” and “GICS Direct” are service marks of S&P and MSCI. Distributor: Royce Fund Services, LLC. |
| Line Graph [Table Text Block] | What Did The Fund Invest In? Representing percentage of total net assets of the Fund as of 6/30/24 (%) Top 10 Positions Portfolio Sector Breakdown CECO Environmental 1.6 Artivion 1.4 Newpark Resources 1.4 Graham Corporation 1.3 American Superconductor 1.3 VSE Corporation 1.3 QuinStreet 1.3 Shoe Carnival 1.3 CRA International 1.3 Arlo Technologies 1.3 |
| Net Assets | $ 132 |
| Holdings Count | shares | 123 |
| Investment Company, Portfolio Turnover | 11% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics As of 6/30/24 Fund Size (Millions) $132 Number of Holdings 123 Turnover Rate 11 |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | |
| Shareholder Report [Line Items] | |
| Fund Name | Royce Capital Fund—Small-Cap Portfolio |
| Class Name | Investment Clas |
| Trading Symbol | RCPFX |
| Annual or Semi-Annual Statement [Text Block] | Semiannual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | semi annual shareholder report |
| Additional Information [Text Block] | Additional information is available at www.royceinvest.com/literature, including its: • Prospectus • Financial Information • Fund Holdings • Proxy Voting Information |
| Material Fund Change Notice [Text Block] | Householding We will deliver a single copy of prospectuses, proxies, financial reports, and other communication to shareholders with the same residential address, provided they have the same last name or we reasonably believe them to be members of the same family. Unless we are notified otherwise, we will continue to send you only one copy of these materials for as long as you remain a shareholder of the Fund. If you would like to receive individual mailings, please call 1-800-221-4268. Please allow 30 days for your request to be processed. Shareholders may also elect to receive these reports electronically. Please go to www.royceinvest.com for more details. |
| Additional Information Phone Number | 1-800-221-4268 |
| Additional Information Website | www.royceinvest.com/literature |
| Expenses [Text Block] | What Were the Fund Costs for the Last Six-Months? Based on a hypothetical $10,000 investment COSTS OF A COSTS PAID AS A PERCENTAGE FUND/CLASS $10,000 INVESTMENT OF A $10,000 INVESTMENT¹ Royce Capital Fund—Small-Cap Portfolio—Investment Class $56 1.14% ¹Annualized |
| Expenses Paid, Amount | $ 56 |
| Expense Ratio, Percent | 1.14% |
| Factors Affecting Performance [Text Block] | Important Information Sector weightings are determined using the Global Industry Classification Standard (“GICS”). GICS was developed by, and is the exclusive property of, Standard & Poor’s Financial Services LLC (“S&P”) and MSCI Inc. (“MSCI”). GICS is the trademark of S&P and MSCI. “Global Industry Classification Standard (GICS)” and “GICS Direct” are service marks of S&P and MSCI. Distributor: Royce Fund Services, LLC |
| Line Graph [Table Text Block] | What Did The Fund Invest In? Representing percentage of total net assets of the Fund as of 6/30/24 (%) Top 10 Positions Sanmina Corporation 1.8 M/I Homes 1.8 SilverBow Resources 1.8 PulteGroup 1.8 Chord Energy 1.7 Flex 1.7 ePlus 1.7 Shoe Carnival 1.6 Evercore Cl. A 1.6 Univest Financial 1.6 Portfolio Sector Breakdown |
| Net Assets | $ 282 |
| Holdings Count | shares | 83 |
| Investment Company, Portfolio Turnover | 16% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics As of 6/30/24 Fund Size (Millions) $ 282 Number of Holdings 83 Turnover Rate 16 |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | |
| Shareholder Report [Line Items] | |
| Fund Name | Royce Capital Fund—Small-Cap Portfolio |
| Class Name | Service Class |
| Trading Symbol | RCSSX |
| Annual or Semi-Annual Statement [Text Block] | Semiannual Shareholder Report |
| Shareholder Report Annual or Semi-Annual | semi annual shareholder report |
| Additional Information [Text Block] | Additional information is available at www.royceinvest.com/literature, including its: • Prospectus • Financial Information • Fund Holdings • Proxy Voting Information |
| Material Fund Change Notice [Text Block] | Householding We will deliver a single copy of prospectuses, proxies, financial reports, and other communication to shareholders with the same residential address, provided they have the same last name or we reasonably believe them to be members of the same family. Unless we are notified otherwise, we will continue to send you only one copy of these materials for as long as you remain a shareholder of the Fund. If you would like to receive individual mailings, please call 1-800-221-4268. Please allow 30 days for your request to be processed. Shareholders may also elect to receive these reports electronically. Please go to www.royceinvest.com for more details. |
| Additional Information Phone Number | 1-800-221-4268 |
| Additional Information Website | www.royceinvest.com/literature |
| Expenses [Text Block] | Based on a hypothetical $10,000 investment COSTS OF A COSTS PAID AS A PERCENTAGE FUND/CLASS $10,000 INVESTMENT OF A $10,000 INVESTMENT¹ Royce Capital Fund—Small-Cap Portfolio—Service Class $67 1.37% ¹Annualized |
| Expenses Paid, Amount | $ 67 |
| Expense Ratio, Percent | 1.37% |
| Factors Affecting Performance [Text Block] | Important Information Sector weightings are determined using the Global Industry Classification Standard (“GICS”). GICS was developed by, and is the exclusive property of, Standard & Poor’s Financial Services LLC (“S&P”) and MSCI Inc. (“MSCI”). GICS is the trademark of S&P and MSCI. “Global Industry Classification Standard (GICS)” and “GICS Direct” are service marks of S&P and MSCI. Distributor: Royce Fund Services, LLC. |
| Line Graph [Table Text Block] | What Did The Fund Invest In? Representing percentage of total net assets of the Fund as of 6/30/24 (%) Top 10 Positions Sanmina Corporation 1.8 M/I Homes 1.8 SilverBow Resources 1.8 PulteGroup 1.8 Chord Energy 1.7 Flex 1.7 ePlus 1.7 Shoe Carnival 1.6 Evercore Cl. A 1.6 Univest Financial 1.6 Portfolio Sector Breakdown |
| Net Assets | $ 282 |
| Holdings Count | shares | 83 |
| Investment Company, Portfolio Turnover | 16% |
| Additional Fund Statistics [Text Block] | Key Fund Statistics As of 6/30/24 Fund Size (Millions) $282 Number of Holdings 83 Turnover Rate 16 |
| Shareholder Report, Holdings (Details) | Jun. 30, 2024 |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Industrials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Information Technology [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Consumer Discretionary [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Health Care [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Communication Services [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.70% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.80% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Materials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Consumer Staples [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Real Estate [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Cash and Cash Equivalents [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | CECO Environmental [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Artivion [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Newpark Resources [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Graham Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | American Superconductor [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | VSE Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | QuinStreet [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Shoe Carnival [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | CRA International [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Investment Class | Arlo Technologies [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Industrials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 26.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Information Technology [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 24.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Consumer Discretionary [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 12.10% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Health Care [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 8.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Communication Services [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 4.70% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.80% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Materials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Consumer Staples [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.70% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Real Estate [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 0.50% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Cash and Cash Equivalents [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 3% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Artivion [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Newpark Resources [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.40% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Graham Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | American Superconductor [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | VSE Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | QuinStreet [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Shoe Carnival [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | Arlo Technologies [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | C E C O Enviromental [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Micro-Cap Portfolio - Service Class | C R A Internationa [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Industrials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.20% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Information Technology [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.70% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Consumer Discretionary [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.90% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.10% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Health Care [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Communication Services [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.60% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Consumer Staples [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Real Estate [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.20% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Cash and Cash Equivalents [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Shoe Carnival [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Sanmina Corporatio [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | M I Homes [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Silver Bow Resources [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Pulte Group [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Chord Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Flex [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | E Plus [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Evercore Cl A [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Small-Cap Portfolio - Investment Class | Univest Financial [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Industrials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 18.20% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Information Technology [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 15.70% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Consumer Discretionary [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 21.90% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Financials [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 20.10% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Health Care [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 5.10% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Communication Services [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.20% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 11.60% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Consumer Staples [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 2.70% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Real Estate [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.20% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Cash and Cash Equivalents [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.30% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Shoe Carnival [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Silver Bow Resources [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Pulte Group [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Chord Energy [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Flex [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | E Plus [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.70% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Univest Financial [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Sanmina Corporation [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | M Or I Homes [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.80% |
| Royce Capital Fund - Small-Cap Portfolio - Service Class | Evercore Cl. A [Member] | |
| Holdings [Line Items] | |
| Percent of Net Asset Value | 1.60% |
