Fair Value of Investments - Schedule of Fair Value Hierarchy of Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2024		Dec. 31, 2023
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	$ 13,194,545	[1],[2],[3],[4]	$ 12,713,348	[5],[6],[7],[8]
Interest rate swaps	(38,241)		$ (45,656)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]			Accrued Liabilities and Other Liabilities
First-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	9,974,880		$ 8,660,754
Second-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	706,800		1,774,984
Unsecured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	301,956		292,751
Preferred equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	371,744		433,297
Common equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	1,543,689		1,208,776
Levels 1, Level 2, and Level 3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Cash (including restricted and foreign cash)	514,156		659,658
Total Investments at fair value	12,702,173		12,370,562
Levels 1, Level 2, and Level 3 | First-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	9,974,880		8,660,754
Levels 1, Level 2, and Level 3 | Second-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	706,800		1,774,984
Levels 1, Level 2, and Level 3 | Unsecured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	301,956		292,751
Levels 1, Level 2, and Level 3 | Preferred equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	371,744		433,297
Levels 1, Level 2, and Level 3 | Common equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	1,346,793		1,208,776
Level 1
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Cash (including restricted and foreign cash)	514,156		659,658
Total Investments at fair value	912		1,093
Interest rate swaps	0		0
Level 1 | First-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 1 | Second-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 1 | Unsecured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 1 | Preferred equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 1 | Common equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	912		1,093
Level 2
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Cash (including restricted and foreign cash)	0		0
Total Investments at fair value	134,000		111,508
Interest rate swaps	(38,241)		0
Level 2 | First-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	87,260		0
Level 2 | Second-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	46,740		99,715
Level 2 | Unsecured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		11,793
Level 2 | Preferred equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 2 | Common equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	0		0
Level 3
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Cash (including restricted and foreign cash)	0		0
Total Investments at fair value	12,567,261		12,257,961
Interest rate swaps	0		(45,656)
Level 3 | First-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	9,887,620		8,660,754
Level 3 | Second-lien senior secured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	660,060		1,675,269
Level 3 | Unsecured debt investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	301,956		280,958
Level 3 | Preferred equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	371,744		433,297
Level 3 | Common equity investments
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	1,345,881		1,207,683
NAV
Fair Value, Investments, Entities that Calculate Net Asset Value Per Share [Line Items]
Total Investments at fair value	$ 492,372		$ 342,786

[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.