Fair Value of Investments - Schedule of Quantitative Information About Significant Unobservable Inputs of Level 3 Investments (Details)	Dec. 31, 2024 USD ($)		Dec. 31, 2023 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 13,194,545,000	[1],[2],[3],[4]	$ 12,713,348,000	[5],[6],[7],[8]
First-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	9,974,880,000		8,660,754,000
Second-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	706,800,000		1,774,984,000
Unsecured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	301,956,000		292,751,000
Preferred equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	371,744,000		433,297,000
Common equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,543,689,000		1,208,776,000
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	12,567,261,000		12,257,961,000
Level 3 | First-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	9,887,620,000		8,660,754,000
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	9,347,861,000		7,553,464,000
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	475,100,000		1,047,390,000
Level 3 | First-lien senior secured debt investments | Collateral Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	64,659,000		59,900,000
Level 3 | Second-lien senior secured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	660,060,000		1,675,269,000
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	655,188,000		1,666,832,000
Level 3 | Second-lien senior secured debt investments | Collateral Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	4,872,000		8,437,000
Level 3 | Unsecured debt investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	301,956,000		280,958,000
Level 3 | Unsecured debt investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	295,601,000		275,158,000
Level 3 | Unsecured debt investments | Market Approach
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	6,355,000		5,800,000
Level 3 | Preferred equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	371,744,000		433,297,000
Level 3 | Preferred equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	362,841,000		396,747,000
Level 3 | Preferred equity investments | Recent Transaction
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			36,550,000
Level 3 | Preferred equity investments | Market Approach
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	8,751,000
Level 3 | Preferred equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	152,000
Level 3 | Common equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,345,881,000		1,207,683,000
Level 3 | Common equity investments | Yield Analysis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	10,498,000
Level 3 | Common equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			9,606,000
Level 3 | Common equity investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value			218,333,000
Level 3 | Common equity investments | Market Approach
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	62,056,000
Level 3 | Common equity investments | Market Approach | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	10,011,000		5,149,000
Level 3 | Common equity investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	1,000,315,000		938,313,000
Level 3 | Common equity investments | Market Approach | Revenue Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	38,412,000		36,138,000
Level 3 | Common equity investments | Market Approach | AUM Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	223,274,000
Level 3 | Common equity investments | Market Approach | Gross Profit Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	180,000		$ 144,000
Level 3 | Common equity investments | Discounted Cash Flow Analysis | Discounted Factor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	778,000
Level 3 | Common equity investments | Option Pricing Model | Volatility
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value	$ 357,000
Level 3 | Minimum | First-lien senior secured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.068		0.091
Level 3 | Minimum | First-lien senior secured debt investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.983		0.970
Level 3 | Minimum | First-lien senior secured debt investments | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.135		0.825
Level 3 | Minimum | Second-lien senior secured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.114		0.114
Level 3 | Minimum | Second-lien senior secured debt investments | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.000		0.133
Level 3 | Minimum | Unsecured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.086		0.106
Level 3 | Minimum | Unsecured debt investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	11.8		11.8
Level 3 | Minimum | Preferred equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.123		0.126
Level 3 | Minimum | Preferred equity investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average			0.980
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	7.1
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	8.5
Level 3 | Minimum | Common equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.085		0.079
Level 3 | Minimum | Common equity investments | Recent Transaction | Transaction Price
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 | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	96.84		92.00
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	1.2		1.2
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	5.3		1.9
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 | Market Approach | Gross Profit Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	10.0		9.9
Level 3 | Minimum | Common equity investments | Discounted Cash Flow Analysis | Discounted Factor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.200
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	0.600
Level 3 | Maximum | First-lien senior secured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.352		0.274
Level 3 | Maximum | First-lien senior secured debt investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	1.000		0.998
Level 3 | Maximum | First-lien senior secured debt investments | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.625		0.825
Level 3 | Maximum | Second-lien senior secured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.198		0.395
Level 3 | Maximum | Second-lien senior secured debt investments | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.040		0.133
Level 3 | Maximum | Unsecured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.181		0.172
Level 3 | Maximum | Unsecured debt investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	11.8		11.8
Level 3 | Maximum | Preferred equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.371		0.258
Level 3 | Maximum | Preferred equity investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average			1.075
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	7.1
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	8.5
Level 3 | Maximum | Common equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.085		0.079
Level 3 | Maximum | Common equity investments | Recent Transaction | Transaction Price
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 | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	96.84		92.00
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	20.0		20.3
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	14.5		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 | Market Approach | Gross Profit Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	10.0		9.9
Level 3 | Maximum | Common equity investments | Discounted Cash Flow Analysis | Discounted Factor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.200
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 | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.113		0.128
Level 3 | Weighted Average | First-lien senior secured debt investments | Recent Transaction | Transaction Price
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 | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.495		0.825
Level 3 | Weighted Average | Second-lien senior secured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.161		0.158
Level 3 | Weighted Average | Second-lien senior secured debt investments | Collateral Analysis | Recovery Rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.040		0.133
Level 3 | Weighted Average | Unsecured debt investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.131		0.120
Level 3 | Weighted Average | Unsecured debt investments | Market Approach | EBITDA Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	11.8		11.8
Level 3 | Weighted Average | Preferred equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.179		0.164
Level 3 | Weighted Average | Preferred equity investments | Recent Transaction | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average			1.044
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	7.1
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	8.5
Level 3 | Weighted Average | Common equity investments | Yield Analysis | Market Yield
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.085		0.079
Level 3 | Weighted Average | Common equity investments | Recent Transaction | Transaction Price
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 | Transaction Price
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	96.84		92.00
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	5.4		5.6
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	11.4		10.5
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 | Market Approach | Gross Profit Multiple
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	10.0		9.9
Level 3 | Weighted Average | Common equity investments | Discounted Cash Flow Analysis | Discounted Factor
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
(Range) Weighted Average	0.200
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	0.698

[1] Non-income producing.

[2] Unless otherwise indicated, all investments are considered Level 3 investments.

[3] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facility and CLOs. See Note 5 “Debt.”

[4] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 27 for additional information on our restricted securities.

[5] Unless otherwise indicated, loan contains a variable rate structure and may be subject to an interest rate floor. Variable rate loans bear interest at a rate that may be determined by reference to either the Secured Overnight Financing Rate (“SOFR” or “S,” which can include one-, three- or six- month SOFR), Euro Interbank Offered Rate (“EURIBOR”), Great Britain Pound London Interbank Offered Rate (“GBPLIBOR” or “G”, which can include three- or six-month GBPLIBOR), SONIA (“SONIA” or “SA”) or an alternate base rate (which can include the Federal Funds Effective Rate or the Prime Rate), at the borrower’s option, and which reset periodically based on the terms of the loan agreement.

[6] Unless otherwise indicated, all investments are considered Level 3 investments.

[7] Unless otherwise indicated, the Company’s portfolio companies are pledged as collateral supporting the amounts outstanding under the Revolving Credit Facility, SPV Asset Facility and CLOs. See Note 5 “Debt”.

[8] Certain portfolio company investments are subject to contractual restrictions on sales. Refer to footnote 26 for additional information on our restricted securities.