Quarterly report [Sections 13 or 15(d)]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.25.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2025
USD ($)
segment
company
Mar. 31, 2024
company
Mar. 31, 2025
USD ($)
company
Dec. 31, 2024
USD ($)
Schedule of Investments [Line Items]        
Cash equivalents | $ $ 45.8   $ 45.8 $ 6.5
Cash exceeded federal deposit insurance corporation insurance protection levels | $ $ 59.7   $ 59.7 $ 67.5
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) 2.90% 3.20%    
Percentage of total investment come, attributable to noncash cumulative dividend income (as a percent) 0.50% 0.30%    
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) 1.70% 1.80%    
Number of operating segments | segment 1      
Number of reportable segments | segment 1      
Revolving Credit Facility | Line of Credit        
Schedule of Investments [Line Items]        
Commitment fee (as a percentage) 3.40%      
Investment Owned, At Fair Value | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 100.00%     100.00%
Investment Owned, At Fair Value | Investment Type Concentration Risk | Non-accrual Status        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 1.70%     0.90%
Investment Owned, At Cost | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 100.00%     100.00%
Investment Owned, At Cost | Investment Type Concentration Risk | Non-accrual Status        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 4.50%     3.50%
LMM portfolio investments        
Schedule of Investments [Line Items]        
Consultation period subsequent to initial investment (in months) 12 months      
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company 15 17 67  
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 (as a percent) 20.00% 24.00% 91.00%  
Private Loan portfolio investments        
Schedule of Investments [Line Items]        
Consultation period subsequent to initial investment (in months) 12 months      
Investment company, number of portfolio companies with annual third-party appraisal was obtained, reviewed and certified | company 14 17 65  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent)     96.00%  
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 26.00% 27.00% 89.00%  
Middle Market portfolio investments        
Schedule of Investments [Line Items]        
Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) 97.00%   97.00% 97.00%
Middle Market portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 2.50%     3.10%
Middle Market portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 3.50%     4.60%
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 2.70%     2.50%
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk        
Schedule of Investments [Line Items]        
Concentration risk (as a percent) 3.10%     2.90%