v3.26.3
Public Notes (Details)
3 Months Ended
Oct. 30, 2025
USD ($)
Sep. 30, 2021
USD ($)
May 27, 2021
USD ($)
Sep. 30, 2026
USD ($)
Sep. 30, 2025
USD ($)
Jun. 30, 2026
USD ($)
Jun. 30, 2025
Jan. 16, 2024
Oct. 01, 2018
Debt Instrument [Line Items]                  
Net realized gains (losses) on extinguishment of debt       $ 1,483,000 $ (77,000)        
Outstanding amount       1,537,158,000   $ 1,878,595,000      
Deferred financing costs on Revolving Credit Facility (Note 4)       12,940,000   14,128,000      
Unsecured Debt                  
Debt Instrument [Line Items]                  
Unamortized discount       $ 3,887,000   $ 5,099,000      
3.364% 2026 Notes                  
Debt Instrument [Line Items]                  
Stated rate       3.364%          
3.364% 2026 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Face amount     $ 300,000,000            
Stated rate     3.364% 3.364%   3.364%      
Issuances of Prospect Capital InterNotes® (Note 7)     $ 293,283,000            
Notes       $ 263,220,000   $ 264,486,000      
Outstanding amount       $ 263,220,000   $ 264,486,000      
2026 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Stated rate       3.364%          
Repayments of long-term debt       $ 1,266,000          
Redemption price rate       99.24%          
Net realized gains (losses) on extinguishment of debt       $ 73,000          
3.437% 2028 Notes                  
Debt Instrument [Line Items]                  
Stated rate       3.437%          
3.437% 2028 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Face amount   $ 300,000,000              
Stated rate   3.437%   3.437%   3.437%      
Issuances of Prospect Capital InterNotes® (Note 7)   $ 291,798,000              
Notes       $ 220,803,000   $ 254,749,000      
Outstanding amount       $ 220,803,000   $ 254,749,000      
2028 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Stated rate       3.437%          
Repayments of long-term debt       $ 33,946,000          
Redemption price rate       93.92%          
Net realized gains (losses) on extinguishment of debt       $ 1,388,000          
5.50% 2030 Notes                  
Debt Instrument [Line Items]                  
Stated rate 5.50%     5.50%          
5.50% 2030 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Face amount $ 167,637,000                
Stated rate 5.50%     5.50%   5.50%      
Issuances of Prospect Capital InterNotes® (Note 7) $ 159,531,000                
Repayments of long-term debt       $ 9,922,000          
Redemption price rate       93.96%          
Net realized gains (losses) on extinguishment of debt       $ 218,000          
Threshold consecutive trading days 60                
Trading days 30                
Outstanding amount       $ 167,755,000   $ 182,153,000      
6.375% 2024 Notes                  
Debt Instrument [Line Items]                  
Stated rate       6.375%     6.375% 6.375%  
6.375% 2024 Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Stated rate                 6.375%
Public Notes                  
Debt Instrument [Line Items]                  
Notes       $ 643,110,000   690,841,000      
Public Notes | Unsecured Debt                  
Debt Instrument [Line Items]                  
Outstanding amount       651,778,000   701,388,000      
Unamortized discount   11,522,000              
Debt issuance costs, gross   $ 11,718,000              
Deferred financing costs on Revolving Credit Facility (Note 4)       4,781,000   $ 5,448,000      
Interest cost       $ 6,916,000 $ 5,784,000