Fair Value of Financial Instruments - Schedule of Quantitative Information About Significant Unobservable Inputs of Level 3 Investments (Details) $ in Thousands	Sep. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 5,083,969	$ 3,807,639
First-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	4,355,248	3,068,392
Second-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	156,068	186,796
Unsecured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	111,413	73,823
Preferred equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	306,747	370,458
Common equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	152,306	108,170
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	4,730,180	3,617,508
Level 3 | First-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	4,070,139	2,898,716
Level 3 | First-lien senior secured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	356,498	423,672
Level 3 | First-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,713,641	2,475,044
Level 3 | Second-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	89,575	186,796
Level 3 | Second-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	89,575	186,796
Level 3 | Unsecured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	111,413	53,368
Level 3 | Unsecured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	3,029	1,700
Level 3 | Unsecured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	108,384	51,668
Level 3 | Preferred equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	306,747	370,458
Level 3 | Preferred equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	22,098	109,877
Level 3 | Preferred equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	223,692	199,839
Level 3 | Preferred equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	6,878
Level 3 | Preferred equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	54,079	60,742
Level 3 | Common equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	152,306	108,170
Level 3 | Common equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value		58,201
Level 3 | Common equity investments | Market Approach
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	10,882
Level 3 | Common equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	24,611	17,724
Level 3 | Common equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	35,839	$ 32,245
Level 3 | Common equity investments | Market Approach | AUM Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	79,219
Level 3 | Common equity investments | Discounted Cash Flow Analysis | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,608
Level 3 | Common equity investments | Option Pricing Model | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 147
Level 3 | Minimum | First-lien senior secured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.980	0.970
Level 3 | Minimum | First-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.066	0.082
Level 3 | Minimum | Second-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.157	0.114
Level 3 | Minimum | Unsecured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.000	1.000
Level 3 | Minimum | Unsecured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.091	0.106
Level 3 | Minimum | Preferred equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.814	0.980
Level 3 | Minimum | Preferred equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.102	0.104
Level 3 | Minimum | Preferred equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	8.4
Level 3 | Minimum | Preferred equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	8.0	8.5
Level 3 | Minimum | Common equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)		1.000
Level 3 | Minimum | Common equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	8.2	9.1
Level 3 | Minimum | Common equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	6.3	6.3
Level 3 | Minimum | Common equity investments | Market Approach | AUM Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.1
Level 3 | Minimum | Common equity investments | Discounted Cash Flow Analysis | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.300
Level 3 | Minimum | Common equity investments | Option Pricing Model | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.700
Level 3 | Maximum | First-lien senior secured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.000	0.993
Level 3 | Maximum | First-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.168	0.171
Level 3 | Maximum | Second-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.159	0.177
Level 3 | Maximum | Unsecured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.000	1.000
Level 3 | Maximum | Unsecured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.144	0.106
Level 3 | Maximum | Preferred equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.000	1.075
Level 3 | Maximum | Preferred equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.215	0.200
Level 3 | Maximum | Preferred equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	8.4
Level 3 | Maximum | Preferred equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	21.0	21.5
Level 3 | Maximum | Common equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)		1.000
Level 3 | Maximum | Common equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	30.5	34.5
Level 3 | Maximum | Common equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	13.5	14.7
Level 3 | Maximum | Common equity investments | Market Approach | AUM Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.1
Level 3 | Maximum | Common equity investments | Discounted Cash Flow Analysis | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.300
Level 3 | Maximum | Common equity investments | Option Pricing Model | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.700
Level 3 | Weighted Average | First-lien senior secured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.990	0.986
Level 3 | Weighted Average | First-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.101	0.120
Level 3 | Weighted Average | Second-lien senior secured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.158	0.153
Level 3 | Weighted Average | Unsecured debt investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.000	1.000
Level 3 | Weighted Average | Unsecured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.106	0.106
Level 3 | Weighted Average | Preferred equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.932	1.069
Level 3 | Weighted Average | Preferred equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.151	0.152
Level 3 | Weighted Average | Preferred equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	8.4
Level 3 | Weighted Average | Preferred equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	12.0	14.6
Level 3 | Weighted Average | Common equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)		1.000
Level 3 | Weighted Average | Common equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	11.5	12.5
Level 3 | Weighted Average | Common equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	10.1	11.2
Level 3 | Weighted Average | Common equity investments | Market Approach | AUM Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	1.1
Level 3 | Weighted Average | Common equity investments | Discounted Cash Flow Analysis | Discount Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.300
Level 3 | Weighted Average | Common equity investments | Option Pricing Model | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Range (Weighted Average)	0.700