Investments - Summary of Investments at Fair Value and Cost (Detail) - USD ($) $ in Thousands	Sep. 30, 2026	Dec. 31, 2025
Investments At Fair Value And Cost [Line Items]
Cost	$ 4,759,876	$ 3,008,238
Fair Value	$ 4,751,045	$ 3,008,628
Percentage of Investments	100.00%	100.00%
First Lien Senior Secured [Member]
Investments At Fair Value And Cost [Line Items]
Cost	$ 4,601,806	$ 2,908,938
Fair Value	$ 4,585,380	$ 2,903,414
Percentage of Investments	96.51%	96.50%
Second Lien Senior Secured [Member]
Investments At Fair Value And Cost [Line Items]
Cost		$ 5,440
Fair Value		$ 5,460
Percentage of Investments		0.18%
Subordinated Notes [Member]
Investments At Fair Value And Cost [Line Items]
Cost		$ 48,779
Fair Value		$ 49,318
Percentage of Investments		1.64%
Collateralized Loan Obligations [Member]
Investments At Fair Value And Cost [Line Items]
Cost	$ 94,415
Fair Value	$ 94,435
Percentage of Investments	1.99%
Preferred Equity [Member]
Investments At Fair Value And Cost [Line Items]
Cost	$ 0	$ 1,989
Fair Value	$ 0	$ 499
Percentage of Investments	0.00%	0.02%
Unlisted Common Stock [Member]
Investments At Fair Value And Cost [Line Items]
Cost	$ 2,877
Fair Value	$ 2,877
Percentage of Investments	0.06%
Limited Partnership Interests [Member]
Investments At Fair Value And Cost [Line Items]
Cost	$ 60,778	$ 43,092
Fair Value	$ 68,353	$ 49,937
Percentage of Investments	1.44%	1.66%