Shareholder Report, Holdings (Details)	Dec. 31, 2025
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Information Technology [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Natural Gas Services Group [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Light Path Technologies Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Investar Holding [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| N L I G H T [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| N W P X Infrastructure [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Bel Fuse Cl B [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Real Real [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Digi International [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Graham Corporation [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.70%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	21.00%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.30%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.80%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.60%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.80%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Real Estate Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Royce Capital Fund - Micro-Cap Portfolio - Investment Class \| Cash and Cash Equivalents [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Information Technology [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Natural Gas Services Group [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Light Path Technologies Cl A [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Investar Holding [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| N L I G H T [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| N W P X Infrastructure [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Bel Fuse Cl B [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Real Real [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Digi International [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Graham Corporation [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.10%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	24.70%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	21.00%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	15.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	12.80%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.60%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.60%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	4.20%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Communications Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.30%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.80%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Real Estate Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	0.40%
Royce Capital Fund - Micro-Cap Portfolio - Service Class \| Cash and Cash Equivalents [Member]
Holdings [Line Items]
Percent of Net Asset Value	3.30%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Diebold Nixdorf [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Lear Corporation [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| I B E X [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Catalyst Pharmaceuticals [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| T D S Y N N E X [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Timberland Bancorp [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Unity Bancorp [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 \| Buckle The [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 \| Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.00%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.50%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	27.90%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.90%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.30%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.70%
Royce Capital Fund-Small-Cap Portfolio - Investment Class \| Cash and Cash Equivalents [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.00%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Diebold Nixdorf [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Lear Corporation [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| I B E X [Member]
Holdings [Line Items]
Percent of Net Asset Value	2.00%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Catalyst Pharmaceuticals [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.90%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| T D S Y N N E X [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Timberland Bancorp [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Unity Bancorp [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| M I Homes [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.80%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Buckle The [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 \| Industrial Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	14.00%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Information Technology Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	13.50%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Financial Services Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	27.90%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Healthcare Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	10.90%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Consumer Discretionary Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	22.30%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Energy Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	7.30%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Materials Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.40%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Consumer Staples Sector [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.70%
Royce Capital Fund-Small-Cap Portfolio - Service Class \| Cash and Cash Equivalents [Member]
Holdings [Line Items]
Percent of Net Asset Value	1.00%

Shareholder Report, Holdings (Details)

Dec. 31, 2025