Quarterly report [Sections 13 or 15(d)]

Fair Value of Financial Instruments - Schedule of Quantitative Information of Fair Value Measurements (Details)

v3.25.3
Fair Value of Financial Instruments - Schedule of Quantitative Information of Fair Value Measurements (Details) - Significant Unobservable Inputs (Level 3)
$ in Thousands
Sep. 30, 2025
USD ($)
Dec. 31, 2024
USD ($)
Total Level 3 Debt Investments and Other Assets (Liabilities)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 4,095,669 $ 3,493,589
Debt investments    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 4,095,558 3,494,601
Debt investments | Debt Investments originated within 6 months    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 675,190 242,833
Debt investments | Imminent Payoffs    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 71,202 4,141
Debt investments | Debt Investments Maturing in Less than One Year    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 232,737 36,185
Debt investments | Debt Investments in Wholly-Owned Subsidiaries    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 38,006 48,212
Escrow Receivables | Expected Proceeds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 145  
Accounts payable and accrued liabilities | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ (34) $ (1,012)
Accounts payable and accrued liabilities | Liquidation | Minimum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1000 0.2000
Accounts payable and accrued liabilities | Liquidation | Maximum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.5000 0.5000
Accounts payable and accrued liabilities | Liquidation | Weighted Average | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.4484 0.3844
Equity Investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 46,346 $ 45,420
Equity Investments | Market Comparable Companies | Minimum | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.2 0.4
Equity Investments | Market Comparable Companies | Minimum | Tangible Book Value Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 1.6 1.7
Equity Investments | Market Comparable Companies | Minimum | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1567 0.1764
Equity Investments | Market Comparable Companies | Maximum | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 16.1 16.8
Equity Investments | Market Comparable Companies | Maximum | Tangible Book Value Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 1.6 1.7
Equity Investments | Market Comparable Companies | Maximum | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.9518 0.9280
Equity Investments | Market Comparable Companies | Weighted Average | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 7.4 9.1
Equity Investments | Market Comparable Companies | Weighted Average | Tangible Book Value Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 1.6 1.7
Equity Investments | Market Comparable Companies | Weighted Average | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.2482 0.3612
Equity Investments | Market Adjusted OPM Backsolve    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 9,934 $ 12,374
Equity Investments | Market Adjusted OPM Backsolve | Minimum | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.8834) (0.9657)
Equity Investments | Market Adjusted OPM Backsolve | Maximum | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.3835 0.2476
Equity Investments | Market Adjusted OPM Backsolve | Weighted Average | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.1230) (0.1757)
Equity Investments | Discounted Cash Flow    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 53,173 $ 34,677
Equity Investments | Discounted Cash Flow | Minimum | Discount Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1129 0.1217
Equity Investments | Discounted Cash Flow | Maximum | Discount Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.3419 0.3334
Equity Investments | Discounted Cash Flow | Weighted Average | Discount Rate    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.2969 0.3021
Equity Investments | Other    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 6,119 $ 5,924
Warrants | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 21,289 $ 18,302
Warrants | Market Comparable Companies | Minimum | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.6 0.8
Warrants | Market Comparable Companies | Minimum | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1565 0.1472
Warrants | Market Comparable Companies | Maximum | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 14.5 14.1
Warrants | Market Comparable Companies | Maximum | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.3310 0.3435
Warrants | Market Comparable Companies | Weighted Average | Revenue Multiple    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 4.4 4.5
Warrants | Market Comparable Companies | Weighted Average | Discount for Lack of Marketability    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.2643 0.2676
Warrants | Market Adjusted OPM Backsolve    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 6,059 $ 3,521
Warrants | Market Adjusted OPM Backsolve | Minimum | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.6022) (0.5636)
Warrants | Market Adjusted OPM Backsolve | Maximum | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.4676 0.2476
Warrants | Market Adjusted OPM Backsolve | Weighted Average | Market Equity Adjustment    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1084 0.0133
Warrants | Other    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 463  
Equity and Warrant Investments    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 143,383 $ 120,218
Pharmaceuticals | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 599,927 $ 947,065
Pharmaceuticals | Debt investments | Market Comparable Companies | Minimum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0800 0.0842
Pharmaceuticals | Debt investments | Market Comparable Companies | Minimum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.0250) (0.0250)
Pharmaceuticals | Debt investments | Market Comparable Companies | Maximum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1495 0.1619
Pharmaceuticals | Debt investments | Market Comparable Companies | Maximum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0200 0.0300
Pharmaceuticals | Debt investments | Market Comparable Companies | Weighted Average | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1192 0.1203
Pharmaceuticals | Debt investments | Market Comparable Companies | Weighted Average | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0028 0.0013
Pharmaceuticals | Debt investments | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments   $ 55,344
Pharmaceuticals | Debt investments | Liquidation | Minimum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input   0.2000
Pharmaceuticals | Debt investments | Liquidation | Maximum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input   0.8000
Pharmaceuticals | Debt investments | Liquidation | Weighted Average | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input   0.7553
Technology | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 1,636,736 $ 1,365,943
Technology | Debt investments | Market Comparable Companies | Minimum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1001 0.1021
Technology | Debt investments | Market Comparable Companies | Minimum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.0150) (0.0075)
Technology | Debt investments | Market Comparable Companies | Maximum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.2106 0.2058
Technology | Debt investments | Market Comparable Companies | Maximum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0550 0.0450
Technology | Debt investments | Market Comparable Companies | Weighted Average | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1262 0.1310
Technology | Debt investments | Market Comparable Companies | Weighted Average | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0034 0.0020
Technology | Debt investments | Convertible Note Analysis    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 29,770 $ 26,869
Technology | Debt investments | Convertible Note Analysis | Minimum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0100 0.0100
Technology | Debt investments | Convertible Note Analysis | Maximum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.7000 0.7000
Technology | Debt investments | Convertible Note Analysis | Weighted Average | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.5107 0.5066
Technology | Debt investments | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 47,720 $ 51,004
Technology | Debt investments | Liquidation | Minimum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1500 0.2200
Technology | Debt investments | Liquidation | Maximum | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.8500 0.7800
Technology | Debt investments | Liquidation | Weighted Average | Probability weighting of alternative outcomes    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.7881 0.6634
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 20,359 $ 21,102
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Minimum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1546 0.1241
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Minimum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0100 0.0025
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Maximum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1546 0.1544
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Maximum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0100 0.0350
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Weighted Average | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1546 0.1525
Sustainable and Renewable Technology | Debt investments | Market Comparable Companies | Weighted Average | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0100 0.0045
Medical Devices | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 74,666 $ 59,645
Medical Devices | Debt investments | Market Comparable Companies | Minimum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1192 0.1179
Medical Devices | Debt investments | Market Comparable Companies | Minimum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input (0.0025) 0.0000
Medical Devices | Debt investments | Market Comparable Companies | Maximum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1395 0.1275
Medical Devices | Debt investments | Market Comparable Companies | Maximum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0050 0.0050
Medical Devices | Debt investments | Market Comparable Companies | Weighted Average | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1310 0.1224
Medical Devices | Debt investments | Market Comparable Companies | Weighted Average | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0011 0.0026
Lower Middle Market | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 669,245 $ 636,258
Lower Middle Market | Debt investments | Market Comparable Companies | Minimum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1002 0.1027
Lower Middle Market | Debt investments | Market Comparable Companies | Minimum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0000 (0.0025)
Lower Middle Market | Debt investments | Market Comparable Companies | Maximum | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1845 0.2100
Lower Middle Market | Debt investments | Market Comparable Companies | Maximum | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0400 0.0500
Lower Middle Market | Debt investments | Market Comparable Companies | Weighted Average | Hypothetical Market Yield    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.1396 0.1412
Lower Middle Market | Debt investments | Market Comparable Companies | Weighted Average | Premium/(Discount)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investment company, investment owned, measurement input 0.0085 0.0107