Quarterly report pursuant to Section 13 or 15(d)

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.23.2
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 3 Months Ended 6 Months Ended 12 Months Ended
Jun. 30, 2023
USD ($)
company
investment
Jun. 30, 2022
company
Jun. 30, 2023
USD ($)
company
investment
Jun. 30, 2022
company
Dec. 31, 2022
USD ($)
investment
Schedule of Investments [Line Items]          
Short-term money market account $ 0.8   $ 0.8   $ 8.3
Money market funds 18.2   18.2    
Cash balances exceeded Federal Deposit Insurance Corporation insurance protection levels $ 10.5   $ 10.5   $ 11.7
Percentage of total investment income, attributable to noncash paid-in-kind interest income 3.40% 3.50% 3.60% 2.70%  
Percentage of total investment come, attributable to noncash cumulative dividend income 0.10% 0.30% 0.10% 1.10%  
Percentage of total investment income, attributable to interest income, debt investments, net 2.60% 2.60% 2.60% 2.70%  
Nonperforming Financial Instruments          
Schedule of Investments [Line Items]          
Number of investments | investment 4   4   7
Investment Owned, At Fair Value | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     100.00%   100.00%
Investment Owned, At Fair Value | Investment Type Concentration Risk | Nonperforming Financial Instruments          
Schedule of Investments [Line Items]          
Concentration risk, percentage     0.30%   0.80%
Investment Owned, At Cost | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     100.00%   100.00%
Investment Owned, At Cost | Investment Type Concentration Risk | Nonperforming Financial Instruments          
Schedule of Investments [Line Items]          
Concentration risk, percentage     2.80%   4.80%
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 26 22 26 22  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified     40.00% 48.00%  
Private Loan portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     36.00% 41.00%  
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 25 24 25 24  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified     59.00% 63.00%  
LMM portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     55.00% 60.00%  
Middle Market portfolio investments          
Schedule of Investments [Line Items]          
Percentage of portfolio investments containing limited consultation with financial advisory services firm 93.00%   93.00%   91.00%
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     2.50%   2.70%
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk          
Schedule of Investments [Line Items]          
Concentration risk, percentage     2.20%   2.30%