Investments - Composition of the Company's Investment Portfolio by Geographic Region, at Amortized Cost and Fair Value (with Corresponding Percentage of Total Portfolio Investments) (Details) - USD ($) $ in Thousands		6 Months Ended		12 Months Ended
		Jun. 30, 2024		Dec. 31, 2023
Investments
Amortized Cost:	[1]	$ 3,376,816		$ 2,523,064
Fair Value	[1]	$ 3,387,141	[2]	$ 2,528,167	[3]
Concentration risk, percentage		100.00%		100.00%
International
Investments
Amortized Cost:		$ 118,879		$ 116,117
Fair Value		$ 114,337		$ 112,077
International | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		3.50%		4.60%
International | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		3.40%		4.40%
Midwest
Investments
Amortized Cost:		$ 624,807		$ 464,411
Fair Value		$ 621,412		$ 462,371
Midwest | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		18.50%		18.40%
Midwest | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		18.40%		18.30%
Northeast
Investments
Amortized Cost:		$ 784,101		$ 602,303
Fair Value		$ 786,786		$ 605,226
Northeast | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		23.20%		23.90%
Northeast | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		23.20%		23.90%
Northwest
Investments
Amortized Cost:		$ 70,159		$ 72,401
Fair Value		$ 72,024		$ 73,706
Northwest | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		2.10%		2.90%
Northwest | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		2.10%		2.90%
Southeast
Investments
Amortized Cost:		$ 764,258		$ 609,720
Fair Value		$ 782,146		$ 616,182
Southeast | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		22.60%		24.20%
Southeast | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		23.10%		24.40%
Southwest
Investments
Amortized Cost:		$ 499,372		$ 303,643
Fair Value		$ 502,113		$ 303,605
Southwest | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		14.80%		12.00%
Southwest | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		14.80%		12.00%
West
Investments
Amortized Cost:		$ 515,240		$ 354,469
Fair Value		$ 508,323		$ 355,000
West | Investment Owned, At Cost | Geographic Concentration Risk
Investments
Concentration risk, percentage		15.30%		14.00%
West | Investment Owned, At Fair Value | Geographic Concentration Risk
Investments
Concentration risk, percentage		15.00%		14.10%

[1] All of the Company’s investments are issued by eligible portfolio companies, as defined in the Investment Company Act of 1940, as amended, (the “1940 Act”), unless otherwise noted. All of the Company’s investments are issued by U.S. portfolio companies unless otherwise noted.

[2] Except as otherwise noted, because there is no readily available market value for these investments, the fair value of each of these investments is determined in good faith using significant unobservable inputs by the Valuation Designee. (See Note 4 in the accompanying notes to the consolidated financial statements).

[3] Except as otherwise noted, because there is no readily available market value for these investments, the fair value of each of these investments is determined in good faith using significant unobservable inputs by the Valuation Designee. (See Note 4 in the accompanying notes to the consolidated financial statements.)