Quarterly report [Sections 13 or 15(d)]

Fair Value of Financial Instruments - Schedule of Investments Measured at Fair Value on Recurring Basis (Details)

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Fair Value of Financial Instruments - Schedule of Investments Measured at Fair Value on Recurring Basis (Details) - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments $ 4,714,760 $ 4,459,584
Accounts payable and accrued liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other liabilities (86) (87)
Senior Secured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,469,019 4,209,798
Unsecured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 71,126 69,614
Preferred Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 53,449 52,735
Common Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 78,659 86,275
Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 42,507 41,162
Investment Funds & Vehicles measured at Net Asset Value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 7,227 7,063
Total Investments, at fair value    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,721,987 4,466,647
Derivative Instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 522 50
Total Investments including cash and cash equivalents and derivative instruments    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,730,589 4,476,947
Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 19,575 21,555
Quoted Prices in Active Markets for Identical Assets (Level 1) | Common Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 19,575 21,555
Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 11,631 13,101
Significant Other Observable Inputs (Level 2) | Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 11,631 13,101
Significant Unobservable Inputs (Level 3)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,683,554 4,424,928
Significant Unobservable Inputs (Level 3) | Accounts payable and accrued liabilities    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other liabilities (86) (87)
Significant Unobservable Inputs (Level 3) | Senior Secured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,469,019 4,209,798
Significant Unobservable Inputs (Level 3) | Unsecured Debt    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 71,126 69,614
Significant Unobservable Inputs (Level 3) | Preferred Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 53,449 52,735
Significant Unobservable Inputs (Level 3) | Common Stock    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 59,084 64,720
Significant Unobservable Inputs (Level 3) | Warrants    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 30,876 28,061
Money Market Fund    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 8,080 10,250
Money Market Fund | Quoted Prices in Active Markets for Identical Assets (Level 1)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 8,080 10,250
Money Market Fund | Significant Other Observable Inputs (Level 2)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 0 0
Money Market Fund | Significant Unobservable Inputs (Level 3)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash and cash equivalents 0 0
Escrow Receivables    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets and liabilities 114 168
Escrow Receivables | Significant Unobservable Inputs (Level 3)    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Other assets and liabilities $ 114 $ 168