Quarterly report [Sections 13 or 15(d)]

INVESTMENTS - Schedule of Changes in Level 3 Fair Value Measurements of Investments (Details)

v3.26.1
INVESTMENTS - Schedule of Changes in Level 3 Fair Value Measurements of Investments (Details) - USD ($)
$ in Thousands
 3 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Mar. 31, 2026
Mar. 31, 2025
New investments, repayments and settlements:        
Cost $ 1,044,448   $ 1,052,848 [1]  
Total        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 1,277,075 $ 1,031,735 1,304,243 $ 974,345
New investments, repayments and settlements:        
Issuances / originations 600 62,842    
Settlements / repayments 0 (4,370)    
Sales 0 0    
Transfers 0 0    
Ending balance 1,277,075 1,031,735    
Change in unrealized (depreciation) appreciation attributable to investments still held (22,389) (1,082)    
Total | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (9,000) 0    
Total | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesUnrealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (22,389) (1,082)    
Reversal of previously recorded (appreciation) depreciation upon realization 3,621 0    
Secured First Lien Debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 564,631 557,057 570,602 514,334
New investments, repayments and settlements:        
Issuances / originations 0 45,941    
Settlements / repayments 0 (4,370)    
Sales 0 0    
Transfers 0 0    
Ending balance 564,631 557,057    
Change in unrealized (depreciation) appreciation attributable to investments still held (592) 1,152    
Secured First Lien Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (9,000) 0    
Secured First Lien Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesUnrealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (592) 1,152    
Reversal of previously recorded (appreciation) depreciation upon realization 3,621 0    
Secured Second Lien Debt        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 102,789 93,340 99,197 103,580
New investments, repayments and settlements:        
Issuances / originations 600 0    
Settlements / repayments 0 0    
Sales 0 0    
Transfers 0 (10,616)    
Ending balance 102,789 93,340    
Change in unrealized (depreciation) appreciation attributable to investments still held 2,992 376    
Secured Second Lien Debt | PSI Molded        
New investments, repayments and settlements:        
Cost   10,600    
Secured Second Lien Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0    
Secured Second Lien Debt | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesUnrealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 2,992 376    
Reversal of previously recorded (appreciation) depreciation upon realization 0 0    
Preferred Equity        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 429,510 325,997 426,949 302,163
New investments, repayments and settlements:        
Issuances / originations 0 16,901    
Settlements / repayments 0 0    
Sales 0 0    
Transfers 0 10,616    
Ending balance 429,510 325,997    
Change in unrealized (depreciation) appreciation attributable to investments still held 2,561 (3,683)    
Preferred Equity | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0    
Preferred Equity | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesUnrealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 2,561 (3,683)    
Reversal of previously recorded (appreciation) depreciation upon realization 0 0    
Common Equity/ Equivalents        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Beginning balance 180,145 55,341 $ 207,495 $ 54,268
New investments, repayments and settlements:        
Issuances / originations 0 0    
Settlements / repayments 0 0    
Sales 0 0    
Transfers 0 0    
Ending balance 180,145 55,341    
Change in unrealized (depreciation) appreciation attributable to investments still held (27,350) 1,073    
Common Equity/ Equivalents | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesRealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) 0 0    
Common Equity/ Equivalents | Income Statement Location [Axis]: us-gaap:DebtAndEquitySecuritiesUnrealizedGainLoss        
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]        
Total gain (loss) (27,350) 1,073    
Reversal of previously recorded (appreciation) depreciation upon realization $ 0 $ 0    
[1] Cumulative gross unrealized appreciation for federal income tax purposes is $428.5 million; cumulative gross unrealized depreciation for federal income tax purposes is $173.7 million. Cumulative net unrealized appreciation is $254.8 million, based on a tax cost of $1.1 billion.