Quarterly report pursuant to Section 13 or 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.23.3
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2023
USD ($)
company
Sep. 30, 2022
company
Sep. 30, 2023
USD ($)
Sep. 30, 2022
Sep. 30, 2023
USD ($)
company
Dec. 31, 2022
USD ($)
Schedule of Investments [Line Items]            
Cash equivalents | $ $ 37.4   $ 37.4   $ 37.4  
Cash exceeded federal deposit insurance corporation insurance protection levels | $ $ 35.0   $ 35.0   $ 35.0 $ 46.3
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) 1.90% 1.20% 2.00% 1.30%    
Percentage of total investment come, attributable to noncash cumulative dividend income (as a percent) 0.30% 0.30% 0.30% 0.50%    
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) 1.90% 1.80% 1.80% 1.90%    
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 Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent)     100.00%     100.00%
Non-accrual Status | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent)     1.00%     0.60%
Non-accrual Status | Investment Owned, At Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent)     3.10%     3.70%
Revolving Credit Facility | Line of Credit            
Schedule of Investments [Line Items]            
Commitment fee (as a percentage)     3.40%      
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 16 15     68  
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) 22.00% 24.00%     94.00%  
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 15 15     62  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent)         95.00%  
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent) 25.00% 20.00%     83.00%  
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% 89.00%
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent)     2.90%     2.80%
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk            
Schedule of Investments [Line Items]            
Concentration risk (as a percent)     3.50%     3.20%