Quarterly report [Sections 13 or 15(d)]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.25.2
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2025
USD ($)
company
Jun. 30, 2024
company
Jun. 30, 2025
USD ($)
segment
Jun. 30, 2024
Jun. 30, 2025
USD ($)
company
Dec. 31, 2024
USD ($)
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     100.00%     100.00%
Cash equivalents | $ $ 21.9   $ 21.9   $ 21.9 $ 14.4
Cash balances exceeded federal deposit insurance corporation insurance protection levels | $ $ 5.3   $ 5.3   $ 5.3 $ 13.5
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) 5.30% 5.00% 5.50% 4.70%    
Percentage of total investment income, attributable to noncash cumulative dividend income (as a percent) 1.50% 0.10% 0.90% 0.10%    
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) 2.30% 2.80% 2.30% 2.70%    
Number of reportable segments | segment     1      
Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     100.00%     100.00%
Investment Owned, At Fair Value | Investment Type Concentration Risk | Nonperforming Financial Instruments            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     2.60%     1.50%
Investment Owned, At Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     100.00%     100.00%
Investment Owned, At Cost | Investment Type Concentration Risk | Nonperforming Financial Instruments            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     6.30%     5.60%
Private Loan portfolio investments            
Schedule of Investments [Line Items]            
Consultation period subsequent to initial investment     12 months      
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company 18 18     62  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent)         97.00%  
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent) 22.00% 22.00%     89.00%  
LMM portfolio investments            
Schedule of Investments [Line Items]            
Consultation period subsequent to initial investment     12 months      
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company 16 14     50  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent)         99.00%  
LMM portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent) 27.00% 27.00%     99.00%  
Middle Market portfolio investments            
Schedule of Investments [Line Items]            
Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) 90.00%   90.00%   90.00% 93.00%
Middle Market portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     2.40%     3.30%
Middle Market portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     3.40%     5.80%
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)     1.30%     2.00%
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk, percentage (as a percent)           1.60%