Investments at Fair Value - Summary of Investments at Fair Value (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2025	Dec. 31, 2024
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	[1]	$ 7,172,247	$ 7,079,994
Fair Value		7,356,032	7,244,282
Net Unrealized Gain (Loss)		183,785	164,288
First-lien Debt Investments
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	[1]	6,720,350	6,732,065
Fair Value		6,864,996	6,871,809
Net Unrealized Gain (Loss)		144,646	139,744
Second-lien Debt Investments
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	[1]	109,967	89,461
Fair Value		122,039	94,778
Net Unrealized Gain (Loss)		12,072	5,317
Mezzanine Debt Investments
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	[1]	198,507	118,441
Fair Value		204,815	123,184
Net Unrealized Gain (Loss)		6,308	4,743
Equity and Other Investments
Schedule Of Available For Sale Securities [Line Items]
Amortized Cost	[1]	143,423	140,027
Fair Value		164,182	154,511
Net Unrealized Gain (Loss)		$ 20,759	$ 14,484

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