Investments - Investment Portfolio at Cost and Fair Value (Details) - USD ($)
$ in Thousands

Mar. 31, 2026

Dec. 31, 2025

Schedule of Investments [Line Items]

$ 25,063,146

^[1]

$ 25,109,408

^[2]

$ 25,007,853

$ 25,337,420

% of Total Investments at Fair Value

100.00%

100.00%

First lien debt

Schedule of Investments [Line Items]

$ 23,898,649

$ 24,169,132

$ 23,859,681

$ 24,395,495

% of Total Investments at Fair Value

95.41%

96.29%

Second lien debt

Schedule of Investments [Line Items]

$ 26,949

$ 26,807

$ 27,742

$ 27,881

% of Total Investments at Fair Value

0.11%

0.11%

Other secured debt

Schedule of Investments [Line Items]

$ 228,881

$ 223,932

$ 228,097

$ 226,763

% of Total Investments at Fair Value

0.91%

0.89%

Schedule of Investments [Line Items]

$ 55,441

$ 60,746

$ 54,450

$ 60,145

% of Total Investments at Fair Value

0.22%

0.24%

Structured Finance

Schedule of Investments [Line Items]

$ 86,290

$ 88,264

$ 84,203

$ 88,664

% of Total Investments at Fair Value

0.34%

0.35%

Investments in Joint Ventures

Schedule of Investments [Line Items]

$ 421,029

$ 402,400

$ 426,214

$ 416,244

% of Total Investments at Fair Value

1.70%

1.64%

Equity investments

Schedule of Investments [Line Items]

$ 345,907

$ 138,127

$ 327,466

$ 122,228

% of Total Investments at Fair Value

1.31%

0.48%

[1]	The cost represents the original cost adjusted for the amortization of discounts and premiums, as applicable, on debt investments using the effective interest method in accordance with U.S. GAAP.
[2]	The cost represents the original cost adjusted for the amortization of discounts and premiums, as applicable, on debt investments using the effective interest method in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”).