Quarterly report [Sections 13 or 15(d)]

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

v3.25.4
INVESTMENTS - Schedule of Changes in Level 3 Fair Value Measurements of Investments (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Sep. 30, 2024
Mar. 31, 2024
New investments, repayments and settlements:                  
Investments, cost $ 1,058,898   $ 1,058,898       $ 939,066 [1]    
Old World Christmas, Inc.                  
New investments, repayments and settlements:                  
Realized gain on preferred equity 3,500   3,500            
PSI Molded                  
New investments, repayments and settlements:                  
Investments, cost           $ 10,600      
Total                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Beginning balance 1,217,717 $ 1,067,230 1,217,717 $ 1,067,230 $ 1,125,784   974,345 $ 853,307 $ 920,486
New investments, repayments and settlements:                  
Issuances / originations 37,438 182,094 171,316 202,192          
Settlements / repayments (15,740) (5,500) (21,546) (33,500)          
Sales (3,481) 0 (3,481) (48,503)          
Transfers 0 0 0 0          
Ending balance 1,217,717 1,067,230 1,217,717 1,067,230          
Total | Debt and Equity Securities, Realized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 3,481 0 (26,457) 42,284          
Total | Debt and Equity Securities, Unrealized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 70,235 37,329 104,436 22,299          
Reversal of previously recorded (appreciation) depreciation upon realization 0 0 19,104 (38,028)          
Secured First Lien Debt                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Beginning balance 604,516 599,911 604,516 599,911 593,979   514,334 469,480 474,856
New investments, repayments and settlements:                  
Issuances / originations 30,140 135,477 126,016 155,575          
Settlements / repayments (15,740) (5,500) (21,546) (8,500)          
Sales 0 0 0 0          
Transfers 0 0 0 0          
Ending balance 604,516 599,911 604,516 599,911          
Secured First Lien Debt | Debt and Equity Securities, Realized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 0 0 (29,938) 0          
Secured First Lien Debt | Debt and Equity Securities, Unrealized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) (3,863) 454 (3,454) (22,020)          
Reversal of previously recorded (appreciation) depreciation upon realization 0 0 19,104 0          
Secured Second Lien Debt                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Beginning balance 90,273 108,743 90,273 108,743 90,633   103,580 111,344 138,703
New investments, repayments and settlements:                  
Issuances / originations 0 0 0 0          
Settlements / repayments 0 0 0 (25,000)          
Sales 0 0 0 0          
Transfers 0 0 (10,616) 0          
Ending balance 90,273 108,743 90,273 108,743          
Secured Second Lien Debt | PSI Molded                  
New investments, repayments and settlements:                  
Investments, cost 10,600   10,600            
Secured Second Lien Debt | Debt and Equity Securities, Realized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 0 0 0 0          
Secured Second Lien Debt | Debt and Equity Securities, Unrealized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) (360) (2,601) (2,691) (4,960)          
Reversal of previously recorded (appreciation) depreciation upon realization 0 0 0 0          
Preferred Equity                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Beginning balance 429,702 308,226 429,702 308,226 365,278   302,163 228,528 213,480
New investments, repayments and settlements:                  
Issuances / originations 7,298 46,617 45,300 46,617          
Settlements / repayments 0 0 0 0          
Sales (3,481) 0 (3,481) 0          
Transfers 0 0 10,616 0          
Ending balance 429,702 308,226 429,702 308,226          
Preferred Equity | Debt and Equity Securities, Realized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 3,481 0 3,481 0          
Preferred Equity | Debt and Equity Securities, Unrealized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 57,126 33,081 71,623 48,129          
Reversal of previously recorded (appreciation) depreciation upon realization 0 0 0 0          
Common Equity/ Equivalents                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Beginning balance 93,226 50,350 93,226 50,350 $ 75,894   $ 54,268 $ 43,955 $ 93,447
New investments, repayments and settlements:                  
Issuances / originations 0 0 0 0          
Settlements / repayments 0 0 0 0          
Sales 0 0 0 (48,503)          
Transfers 0 0 0 0          
Ending balance 93,226 50,350 93,226 50,350          
Common Equity/ Equivalents | Debt and Equity Securities, Realized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 0 0 0 42,284          
Common Equity/ Equivalents | Debt and Equity Securities, Unrealized Gain (Loss)                  
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]                  
Total gain (loss) 17,332 6,395 38,958 1,150          
Reversal of previously recorded (appreciation) depreciation upon realization $ 0 $ 0 $ 0 $ (38,028)          
[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.