Investments - Fair Value and Amortized Cost (Details) - USD ($) $ in Thousands	Mar. 31, 2025		Dec. 31, 2024		Mar. 31, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Amortized Cost	$ 3,382,281	[1],[2],[3]	$ 3,159,171	[4],[5],[6]
Fair Value	3,384,519	[2],[3]	3,161,223	[5],[6]
Non-controlled/non-affiliated
Schedule of Investments [Line Items]
Amortized Cost	3,304,424	[1]	3,084,619	[4]
Fair Value	3,298,961		3,080,569
Non-controlled/affiliated
Schedule of Investments [Line Items]
Amortized Cost	77,857	[1]	74,552	[4]
Fair Value	85,558		80,654		$ 62,126	$ 54,714
First lien senior secured debt | Non-controlled/non-affiliated
Schedule of Investments [Line Items]
Amortized Cost	3,304,409		3,084,605
Fair Value	3,298,945		3,080,554
Sponsor subordinated note | Non-controlled/non-affiliated
Schedule of Investments [Line Items]
Amortized Cost	15		14
Fair Value	$ 16		$ 15

[1] The amortized cost represents the original cost adjusted for the amortization of discounts and premiums, as applicable, on debt investments using the effective interest method.

[2] Unless otherwise indicated, all investments represent co-investments made with the Company’s affiliates in accordance with the terms of the exemptive relief that the Company received from the U.S. Securities and Exchange Commission. Refer to Note 6 for further information.

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

[4] The amortized cost represents the original cost adjusted for the amortization of discounts and premiums, as applicable, on debt investments using the effective interest method.

[5] Unless otherwise indicated, all investments represent co-investments made with the Company’s affiliates in accordance with the terms of the exemptive relief that the Company received from the U.S. Securities and Exchange Commission. Refer to Note 6 for further information.

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