Agreements and Related Party Transactions - Summary of Investments in Controlled Affiliates (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	$ 1,582,075
Net Realized Gains/ (Losses)	2,108	$ (161,456)	$ (5,482)
Fair Value, Ending balance	1,598,857	1,582,075
Controlled Affiliated
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	63,919	11,375
Gross Additions	1,293	55,854
Gross Reductions	(8,673)	(2,139)
Net Realized Gains/ (Losses)	6,443
Change in Unrealized Gains/ (Losses)	(14,931)	(1,171)
Fair Value, Ending balance	48,051	63,919	11,375
Dividend, Interest, PIK and Other Income	10,869	11,601
Controlled Affiliated | Envocore LLC
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	10,375	11,375
Gross Additions	1,615	248
Gross Reductions	(695)	(69)
Change in Unrealized Gains/ (Losses)	(2,074)	(1,179)
Fair Value, Ending balance	9,221	10,375	$ 11,375
Dividend, Interest, PIK and Other Income	614	801
Controlled Affiliated | First Eagle Logan JV, LLC
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	39,004
Gross Additions		44,768
Gross Reductions	(2,559)	(796)
Change in Unrealized Gains/ (Losses)	(3,870)	(4,968)
Fair Value, Ending balance	32,575	39,004
Dividend, Interest, PIK and Other Income	9,784	10,800
Controlled Affiliated | Loadmaster Derrick & Equipment, Inc.
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	6,287
Gross Additions		1,807
Gross Reductions	(3,750)	(250)
Net Realized Gains/ (Losses)	6,443
Change in Unrealized Gains/ (Losses)	(5,504)	4,730
Fair Value, Ending balance	3,476	6,287
Dividend, Interest, PIK and Other Income	471
Controlled Affiliated | OEM Group, LLC
Investments In And Advances To Affiliates [Line Items]
Fair Value, Beginning balance	8,253
Gross Additions	(322)	9,031
Gross Reductions	(1,669)	(1,024)
Change in Unrealized Gains/ (Losses)	(3,483)	246
Fair Value, Ending balance	$ 2,779	8,253
Dividend, Interest, PIK and Other Income		$ 0