v3.26.1
Prospect Capital InterNotes® - Schedule Issued Notes (Details) - Prospect Capital InterNotes® - USD ($)
$ in Thousands
12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2024
Debt Instrument [Line Items]      
Principal Amount $ 29,799 $ 151,592 $ 156,840
Unsecured Debt      
Debt Instrument [Line Items]      
Principal Amount $ 29,799 $ 151,592  
Weighted Average Interest Rate 6.85% 7.15%  
Unsecured Debt | Minimum      
Debt Instrument [Line Items]      
Interest Rate Range 6.25% 6.50%  
Unsecured Debt | Maximum      
Debt Instrument [Line Items]      
Interest Rate Range 8.00% 8.00%  
Unsecured Debt | Maturity Date Range One      
Debt Instrument [Line Items]      
Tenor at Origination (in years) 3 years 3 years  
Principal Amount $ 20,095 $ 60,429  
Weighted Average Interest Rate 6.68% 6.96%  
Unsecured Debt | Maturity Date Range One | Minimum      
Debt Instrument [Line Items]      
Interest Rate Range 6.25% 6.50%  
Unsecured Debt | Maturity Date Range One | Maximum      
Debt Instrument [Line Items]      
Interest Rate Range 7.50% 7.50%  
Unsecured Debt | Maturity Date Range Two      
Debt Instrument [Line Items]      
Tenor at Origination (in years) 5 years 5 years  
Principal Amount $ 3,151 $ 48,993  
Weighted Average Interest Rate 7.02% 7.18%  
Unsecured Debt | Maturity Date Range Two | Minimum      
Debt Instrument [Line Items]      
Interest Rate Range 6.50% 6.75%  
Unsecured Debt | Maturity Date Range Two | Maximum      
Debt Instrument [Line Items]      
Interest Rate Range 7.75% 7.75%  
Unsecured Debt | Maturity Date Range Three      
Debt Instrument [Line Items]      
Tenor at Origination (in years) 7 years 7 years  
Principal Amount $ 6,553 $ 718  
Weighted Average Interest Rate 7.28% 8.00%  
Unsecured Debt | Maturity Date Range Three | Minimum      
Debt Instrument [Line Items]      
Interest Rate Range 6.75% 8.00%  
Unsecured Debt | Maturity Date Range Three | Maximum      
Debt Instrument [Line Items]      
Interest Rate Range 8.00% 8.00%  
Unsecured Debt | Maturity Date Range Four      
Debt Instrument [Line Items]      
Tenor at Origination (in years)   10 years  
Principal Amount   $ 41,452  
Weighted Average Interest Rate   7.39%  
Unsecured Debt | Maturity Date Range Four | Minimum      
Debt Instrument [Line Items]      
Interest Rate Range   7.00%  
Unsecured Debt | Maturity Date Range Four | Maximum      
Debt Instrument [Line Items]      
Interest Rate Range   7.75%