Quarterly report [Sections 13 or 15(d)]

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

v3.25.1
Fair Value of Financial Instruments - Schedule of Quantitative Information of Fair Value Measurements (Details) - Significant Unobservable Inputs (Level 3)
$ in Thousands
Mar. 31, 2025
USD ($)
Dec. 31, 2024
USD ($)
Total Level Three Debt Investments and Other Investment Receivables (Payables)    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 3,740,228 $ 3,493,589
Debt investments    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 3,739,234 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 516,515 242,833
Debt investments | Imminent Payoffs    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 214,238 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 82,666 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 36,790 48,212
Escrow and Other Investment Receivables | Expected Proceeds    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments 1,966  
Accounts payable and accrued liabilities | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ (972) $ (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 0.2000 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 0.3979 0.3844
Equity and Warrant Investments    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 132,141 $ 120,218
Equity Investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 48,390 $ 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 0.1631 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 16.5 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 0.9253 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 7.0 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 0.3334 0.3612
Equity Investments | Market Adjusted OPM Backsolve    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 7,237 $ 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 (0.9768) (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 (0.0065) 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 (0.3032) (0.1757)
Equity Investments | Discounted Cash Flow    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 50,151 $ 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 0.1155 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 0.3294 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 0.2955 0.3021
Equity Investments | Other    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 5,778 $ 5,924
Warrants | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 18,779 $ 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 0.5 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 0.0736 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 12.9 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 0.3240 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 4.3 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 0.2428 0.2676
Warrants | Market Adjusted OPM Backsolve    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 1,806 $ 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 (0.7008) (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 0.5433 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 (0.0387) 0.0133
Pharmaceuticals | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 787,506 $ 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 0.0878 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 0.1634 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 0.0300 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 0.1290 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 0.0017 0.0013
Pharmaceuticals | Debt investments | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 73,719 $ 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 0.1000 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 0.9000 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 0.8032 0.7553
Technology | Debt investments | Market Comparable Companies    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 1,281,565 $ 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 0.0981 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 (0.0100) (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 0.2118 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 0.0500 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 0.1321 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 0.0017 0.0020
Technology | Debt investments | Liquidation    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 53,584 $ 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 0.1000 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 0.7250 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 0.6035 0.6634
Technology | Debt investments | Convertible Note Analysis    
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]    
Investments $ 27,673 $ 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 0.5094 0.5066
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 $ 19,903 $ 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 0.1578 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 0.0050 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 0.1578 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 0.0050 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 0.1578 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 0.0050 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 $ 59,851 $ 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 0.1181 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 0.0000 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 0.1277 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 0.1226 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 0.0026 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 $ 585,224 $ 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 0.1043 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 (0.0075) (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 0.1748 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 0.0225 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 0.1363 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 0.0058 0.0107