Annual report pursuant to Section 13 and 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.24.0.1
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2023
USD ($)
company
Dec. 31, 2022
USD ($)
company
Dec. 31, 2021
Schedule of Investments [Line Items]      
Cash equivalents | $ $ 15.2    
Cash exceeded Federal Deposit Insurance Corporation insurance protection levels | $ $ 40.1 $ 46.3  
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) 2.20% 1.40% 2.60%
Percentage of total investment come, attributable to noncash cumulative dividend income (as a percent) 0.30% 0.50% 0.60%
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) 1.80% 1.80% 2.00%
Credit Facility | Line of Credit      
Schedule of Investments [Line Items]      
Commitment fee (as a percent) 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) 0.60% 0.60%  
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) 2.30% 3.70%  
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 70 66  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) 99.00% 99.00%  
LMM portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 95.00% 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 59 59  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) 94.00% 97.00%  
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 82.00% 76.00%  
Middle Market portfolio investments      
Schedule of Investments [Line Items]      
Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) 98.00% 89.00%  
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 3.30% 2.80%  
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 4.00% 3.20%