Fair Value of Financial Instruments - Fair Value of Level 3 Investments at Fair Value Significant Unobservable Inputs Used in Valuations (Details) - Level 3 $ in Thousands	Sep. 30, 2023 USD ($)	Dec. 31, 2022 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 2,046,858	$ 808,801
Income Approach | First-lien Debt Investments | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 1,915,102	$ 800,995
Income Approach | First-lien Debt Investments | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.098	0.093
Income Approach | First-lien Debt Investments | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.175	0.151
Income Approach | First-lien Debt Investments | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.129	0.131
Income Approach | Second-lien Debt Investments | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.15
Income Approach | Second-lien Debt Investments | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.15
Income Approach | Second-lien Debt Investments | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.15
Income Approach | Mezzanine Debt Investments | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 101,497
Market Multiple | Equity and Other Investments | Comparable Multiple | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.026	0.058
Market Multiple | Equity and Other Investments | Comparable Multiple | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.142	0.135
Market Multiple | Equity and Other Investments | Comparable Multiple | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.104	0.133
Transaction value | Equity and Other Investments | Cost
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 30,259	$ 7,806