Annual report [Section 13 and 15(d), not S-K Item 405]

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)

v3.25.4
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2025
USD ($)
segment
company
Dec. 31, 2024
USD ($)
company
Dec. 31, 2023
Schedule of Investments [Line Items]      
Cash equivalents | $ $ 3.2 $ 6.5  
Cash exceeded federal deposit insurance corporation insurance protection levels | $ $ 35.4 $ 67.5  
Percentage of total investment income, attributable to noncash paid-in-kind interest income (as a percent) 2.80% 4.20% 2.20%
Percentage of total investment come, attributable to noncash cumulative dividend income (as a percent) 0.70% 0.50% 0.30%
Percentage of total investment income, attributable to interest income, debt investments, net (as a percent) 1.70% 2.00% 1.80%
Number of reportable segments | segment 1    
Number of operating segments | segment 1    
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% 0.90%  
Non-accrual Status | Investment Owned, At Cost | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 3.30% 3.50%  
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 71 68  
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) 88.00% 93.00%  
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 61 66  
Percentage of portfolio with annual third-party appraisal was obtained, reviewed and certified (as a percent) 98.00% 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) 87.00% 85.00%  
Middle Market portfolio investments      
Schedule of Investments [Line Items]      
Percentage of portfolio investments containing limited consultation with financial advisory services firm (as a percent) 95.00% 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) 1.50% 3.10%  
Middle Market portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 2.50% 4.60%  
Other Portfolio investments | Investment Owned, At Fair Value | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 2.40% 2.50%  
Other Portfolio investments | Investment Owned, At Cost | Investment Type Concentration Risk      
Schedule of Investments [Line Items]      
Concentration risk (as a percent) 3.00% 2.90%