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	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 7,240,367	$ 7,099,575
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	$ 6,838,709	$ 6,728,411
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	0.065	0.077
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	0.147	0.171
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	0.101	0.106
Income Approach | Second-lien Debt Investments | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 32,265	$ 93,469
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	0.131	0.147
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	0.141	0.181
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	0.138	0.178
Income Approach | Mezzanine Debt Investments | Discount Rate
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 210,092	$ 123,184
Income Approach | Mezzanine Debt Investments | Discount Rate | Minimum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.115	0.122
Income Approach | Mezzanine Debt Investments | Discount Rate | Maximum
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.115	0.122
Income Approach | Mezzanine Debt Investments | Discount Rate | Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Investment measurement input	0.115	0.122
Market Multiple | Equity and Other Investments | Comparable Multiple
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Fair Value	$ 159,301	$ 154,511
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	0.019	0.048
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	0.20	0.20
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	0.112	0.11