Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Narrative (Details)

v3.25.2
INVESTMENTS - Narrative (Details)
$ in Thousands
 1 Months Ended 3 Months Ended
May 31, 2025
USD ($)
Jun. 30, 2025
USD ($)
portfolioCompany
industry
state
Jun. 30, 2024
USD ($)
Mar. 31, 2025
USD ($)
Summary of Investment Holdings [Line Items]        
Purchase of investments   $ 62,842 $ 598  
Cost   $ 997,538   $ 939,066 [1]
Number of investment portfolio company | portfolioCompany   27    
Number of states or countries which have invested in the company location | state   20    
Number of industries that have made investments | industry   16    
Investments owned, fair value   $ 1,036,745   979,320 [1]
Uncollectible receivables allowance, minimum required day for uncollectible adjustment   90 days    
Gross receivables from portfolio companies   $ 2,700   2,300
Allowance for uncollectible receivables   1,500   1,700
Five Largest Portfolio Investments | Investment Portfolio Benchmark | Customer Concentration Risk        
Summary of Investment Holdings [Line Items]        
Investments owned, fair value   $ 403,100    
Percentage of total investments   38.90%    
Secured First Lien Debt        
Summary of Investment Holdings [Line Items]        
Cost   $ 625,596   584,026
Investments owned, fair value   557,057   514,334
Preferred Equity        
Summary of Investment Holdings [Line Items]        
Cost   229,005   201,487
Investments owned, fair value   325,997   $ 302,163
Smart Chemical        
Summary of Investment Holdings [Line Items]        
Purchase of investments $ 49,500      
Smart Chemical | Secured First Lien Debt        
Summary of Investment Holdings [Line Items]        
Purchase of investments 35,700      
Smart Chemical | Preferred Equity        
Summary of Investment Holdings [Line Items]        
Purchase of investments 13,800      
Sun State        
Summary of Investment Holdings [Line Items]        
Purchase of investments 12,800      
Sun State | Secured First Lien Debt        
Summary of Investment Holdings [Line Items]        
Purchase of investments 9,800      
Sun State | Preferred Equity        
Summary of Investment Holdings [Line Items]        
Purchase of investments $ 3,100      
PSI Molded        
Summary of Investment Holdings [Line Items]        
Cost   $ 10,600    
[1] Cumulative gross unrealized appreciation for federal income tax purposes is $183.3 million; cumulative gross unrealized depreciation for federal income tax purposes is $144.9 million. Cumulative net unrealized appreciation is $38.5 million, based on a tax cost of $940.9 million.