INVESTMENTS - Schedule of Industry Composition of Investment at Fair Value (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2025	Dec. 31, 2024
Schedule of Investments [Line Items]
Fair Value	$ 2,571,228	$ 2,449,272
Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	1,081,889	1,095,308
Jocassee Partners LLC \| Investment, Excluding Short Term Investment, with Previous Commitment to Provide Financing
Schedule of Investments [Line Items]
Fair Value	1,066,250	1,085,025
Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 25,115	$ 33,422
Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	100.00%	100.00%
Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	100.00%	100.00%
Aerospace & Defense \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 58,174	$ 61,069
Aerospace & Defense \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	5.00%	6.00%
Automotive \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 12,547	$ 11,236
Automotive \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 0	$ 2,746
Automotive \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Automotive \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	8.00%
Banking, Finance, Insurance, & Real Estate \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 116,515	$ 115,269
Banking, Finance, Insurance, & Real Estate \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 0	$ 33
Banking, Finance, Insurance, & Real Estate \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	11.00%	11.00%
Banking, Finance, Insurance, & Real Estate \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Beverage, Food, & Tobacco \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 31,883	$ 28,657
Beverage, Food, & Tobacco \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 3,750	$ 3,578
Beverage, Food, & Tobacco \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	3.00%	3.00%
Beverage, Food, & Tobacco \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	15.00%	11.00%
Capital Equipment \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 13,413	$ 13,376
Capital Equipment \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Chemicals, Plastics, & Rubber \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 26,491	$ 30,248
Chemicals, Plastics, & Rubber \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 2,971	$ 2,954
Chemicals, Plastics, & Rubber \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	3.00%
Chemicals, Plastics, & Rubber \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	12.00%	9.00%
Construction & Building \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 24,073	$ 21,805
Construction & Building \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	2.00%
Consumer goods: Durable \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 22,351	$ 26,531
Consumer goods: Durable \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 263	$ 232
Consumer goods: Durable \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	2.00%
Consumer goods: Durable \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Consumer goods: Non-durable \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 22,863	$ 21,629
Consumer goods: Non-durable \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	2.00%
Containers, Packaging, & Glass \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 28,413	$ 28,616
Containers, Packaging, & Glass \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	3.00%	3.00%
Energy: Electricity \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 9,867	$ 10,005
Energy: Electricity \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Energy: Oil & Gas \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 12,223	$ 11,209
Energy: Oil & Gas \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Environmental Industries \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 6,051	$ 6,237
Environmental Industries \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	0.00%
Forest Products & Paper \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 1,140	$ 1,156
Forest Products & Paper \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Healthcare & Pharmaceuticals \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 116,717	$ 113,530
Healthcare & Pharmaceuticals \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 0	$ 3,821
Healthcare & Pharmaceuticals \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	11.00%	10.00%
Healthcare & Pharmaceuticals \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	11.00%
High Tech Industries \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 93,469	$ 87,247
High Tech Industries \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 9,289	$ 9,363
High Tech Industries \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	9.00%	8.00%
High Tech Industries \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	37.00%	28.00%
Hotel, Gaming, & Leisure \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 21,258	$ 22,031
Hotel, Gaming, & Leisure \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	2.00%
Investment Funds & Vehicles \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 17,067	$ 20,427
Investment Funds & Vehicles \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	2.00%
Media: Advertising, Printing, & Publishing \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 17,579	$ 10,420
Media: Advertising, Printing, & Publishing \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	2.00%	1.00%
Media: Broadcasting & Subscription \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 16,356	$ 17,297
Media: Broadcasting & Subscription \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	2.00%
Media: Diversified & Production \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 48,538	$ 41,913
Media: Diversified & Production \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%	4.00%
Metals & Mining \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 4,035	$ 4,028
Metals & Mining \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%
Retail \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 9,137	$ 12,361
Retail \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Services: Business \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 177,600	$ 213,492
Services: Business \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 4,244	$ 4,411
Services: Business \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	17.00%	20.00%
Services: Business \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	17.00%	13.00%
Services: Consumer \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 59,822	$ 58,080
Services: Consumer \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	6.00%	5.00%
Telecommunications \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 37,325	$ 36,205
Telecommunications \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%	3.00%
Transportation: Cargo \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 41,871	$ 41,968
Transportation: Cargo \| Sierra JV
Schedule of Investments [Line Items]
Fair Value	$ 4,598	$ 6,284
Transportation: Cargo \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	4.00%	4.00%
Transportation: Cargo \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Sierra JV
Schedule of Investments [Line Items]
Percentage of Total Portfolio	18.00%	19.00%
Transportation: Consumer \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 8,900	$ 8,529
Transportation: Consumer \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Utilities: Electric \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 10,375	$ 10,454
Utilities: Electric \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	1.00%	1.00%
Utilities: Oil & Gas \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Fair Value	$ 197	$ 0
Utilities: Oil & Gas \| Percentage of Total Portfolio, at Fair Value \| Industry Concentration Risk \| Jocassee Partners LLC
Schedule of Investments [Line Items]
Percentage of Total Portfolio	0.00%	0.00%