INVESTMENTS - Composition of Investments at Fair Value (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2024	Dec. 31, 2023
Schedule of Investments [Line Items]
Cost		$ 3,813,127	$ 3,226,776
Fair Value		$ 3,791,494	$ 3,193,561
Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		100.00%	100.00%
Australia
Schedule of Investments [Line Items]
Cost		$ 8,798	$ 16,985
Fair Value		$ 8,970	$ 17,048
Australia | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.20%	0.50%
Canada
Schedule of Investments [Line Items]
Cost		$ 153,734	$ 98,674
Fair Value		$ 154,953	$ 98,387
Canada | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		4.10%	3.10%
United Kingdom
Schedule of Investments [Line Items]
Cost		$ 12,411	$ 12,398
Fair Value		$ 12,196	$ 12,629
United Kingdom | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.30%	0.40%
United States
Schedule of Investments [Line Items]
Cost		$ 3,638,184	$ 3,098,719
Fair Value		$ 3,615,375	$ 3,065,497
United States | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		95.40%	96.00%
Aerospace & Defense | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.20%	2.20%
Air Freight & Logistics | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.30%	1.10%
Automobile Components | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		3.00%	3.50%
Automobiles | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		3.60%	4.70%
Biotechnology | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.70%	0.50%
Building Products | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.40%	0.00%
Chemicals | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.50%	0.60%
Commercial Services & Supplies | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		9.10%	9.60%
Construction & Engineering | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.00%	1.50%
Consumer Staples Distribution & Retail | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.70%	0.00%
Containers & Packaging | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		1.20%	1.40%
Distributors | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.30%	2.90%
Diversified Consumer Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		4.70%	2.50%
Electrical Equipment | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.10%	0.00%
Electronic Equipment, Instruments & Components | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.10%	2.10%
Energy Equipment & Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.00%	0.50%
Financial Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.50%	1.90%
Food Products | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.00%	2.30%
Ground Transportation | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.60%	0.00%
Health Care Equipment & Supplies | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.60%	0.70%
Health Care Providers & Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		5.00%	4.60%
Health Care Technology | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		1.60%	1.90%
Industrial Conglomerates | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		1.20%	1.30%
Insurance Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		12.00%	14.90%
Interactive Media & Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		2.60%	3.20%
IT Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		8.90%	8.70%
Leisure Products | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.00%	0.70%
Life Sciences Tools & Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.30%	0.00%
Machinery | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.90%	2.10%
Multi-Utilities | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.60%	0.70%
Pharmaceuticals | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.30%	0.40%
Professional Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		5.40%	3.80%
Real Estate Management & Development | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		3.60%	5.30%
Software | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		18.90%	14.20%
Wireless Telecommunication Services | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.10%	0.20%
First Lien Debt
Schedule of Investments [Line Items]
Cost		$ 3,669,886	$ 3,027,413
Fair Value		$ 3,654,538	$ 3,004,544
First Lien Debt | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		96.50%	94.10%
First Lien Debt | Aerospace & Defense
Schedule of Investments [Line Items]
Cost	[1]		$ 69,354
Fair Value			69,364
First Lien Debt | Air Freight & Logistics
Schedule of Investments [Line Items]
Cost	[1]		30,213
Fair Value			29,744
First Lien Debt | Automobile Components
Schedule of Investments [Line Items]
Cost	[1]		86,754
Fair Value			86,173
First Lien Debt | Automobiles
Schedule of Investments [Line Items]
Cost	[1]		151,741
Fair Value			150,980
First Lien Debt | Biotechnology
Schedule of Investments [Line Items]
Cost	[1]		15,580
Fair Value			15,619
First Lien Debt | Chemicals
Schedule of Investments [Line Items]
Cost	[1]		20,940
Fair Value			20,481
First Lien Debt | Commercial Services & Supplies
Schedule of Investments [Line Items]
Cost	[1]		306,475
Fair Value			304,534
First Lien Debt | Construction & Engineering
Schedule of Investments [Line Items]
Cost	[1]		47,178
Fair Value			46,877
First Lien Debt | Containers & Packaging
Schedule of Investments [Line Items]
Cost	[1]		43,466
Fair Value			43,688
First Lien Debt | Distributors
Schedule of Investments [Line Items]
Cost	[1]		98,033
Fair Value			93,930
First Lien Debt | Diversified Consumer Services
Schedule of Investments [Line Items]
Cost	[1]		81,164
Fair Value			80,159
First Lien Debt | Electronic Equipment, Instruments & Components
Schedule of Investments [Line Items]
Cost	[1]		45,611
Fair Value			44,711
First Lien Debt | Financial Services
Schedule of Investments [Line Items]
Cost	[1]		59,701
Fair Value			59,992
First Lien Debt | Food Products
Schedule of Investments [Line Items]
Cost	[1]		73,733
Fair Value			72,784
First Lien Debt | Health Care Equipment & Supplies
Schedule of Investments [Line Items]
Cost	[1]		22,434
Fair Value			22,614
First Lien Debt | Health Care Providers & Services
Schedule of Investments [Line Items]
Cost	[1]		139,406
Fair Value			138,138
First Lien Debt | Health Care Technology
Schedule of Investments [Line Items]
Cost	[1]		61,205
Fair Value			61,443
First Lien Debt | Industrial Conglomerates
Schedule of Investments [Line Items]
Cost	[1]		33,707
Fair Value			34,595
First Lien Debt | Insurance Services
Schedule of Investments [Line Items]
Cost	[1]		472,289
Fair Value			471,507
First Lien Debt | Interactive Media & Services
Schedule of Investments [Line Items]
Cost	[1]		104,479
Fair Value			100,782
First Lien Debt | IT Services
Schedule of Investments [Line Items]
Cost	[1]		230,636
Fair Value			224,725
First Lien Debt | Leisure Products
Schedule of Investments [Line Items]
Cost	[1]		21,552
Fair Value			21,453
First Lien Debt | Machinery
Schedule of Investments [Line Items]
Cost	[1]		68,230
Fair Value			66,966
First Lien Debt | Multi-Utilities
Schedule of Investments [Line Items]
Cost	[1]		20,654
Fair Value			20,828
First Lien Debt | Pharmaceuticals
Schedule of Investments [Line Items]
Cost	[1]		12,398
Fair Value			12,629
First Lien Debt | Professional Services
Schedule of Investments [Line Items]
Cost	[1]		116,655
Fair Value			118,043
First Lien Debt | Real Estate Management & Development
Schedule of Investments [Line Items]
Cost			168,456
Fair Value			168,090
First Lien Debt | Software
Schedule of Investments [Line Items]
Cost	[1]		419,529
Fair Value			417,855
First Lien Debt | Wireless Telecommunication Services
Schedule of Investments [Line Items]
Cost			5,840
Fair Value			5,840
Second Lien Debt
Schedule of Investments [Line Items]
Cost		$ 78,803	146,014
Fair Value		$ 69,367	$ 132,415
Second Lien Debt | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		1.80%	4.10%
Second Lien Debt | Health Care Providers & Services
Schedule of Investments [Line Items]
Cost	[1]		$ 5,419
Fair Value			5,387
Second Lien Debt | IT Services
Schedule of Investments [Line Items]
Cost	[1]		40,092
Fair Value			36,979
Second Lien Debt | Software
Schedule of Investments [Line Items]
Cost			23,808
Fair Value			19,233
Other Debt Investments
Schedule of Investments [Line Items]
Cost		$ 9,755	3,410
Fair Value		$ 9,198	$ 2,064
Other Debt Investments | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		0.20%	0.10%
Equity
Schedule of Investments [Line Items]
Cost		$ 54,683	$ 49,939
Fair Value		$ 58,391	$ 54,538
Equity | Investment Owned at Fair Value | Investment Type Concentration Risk
Schedule of Investments [Line Items]
% of Total Investments at Fair Value		1.50%	1.70%
Equity | Aerospace & Defense
Schedule of Investments [Line Items]
Cost		$ 654
Fair Value		446
Equity | Automobile Components
Schedule of Investments [Line Items]
Cost		850
Fair Value		1,463
Equity | Commercial Services & Supplies
Schedule of Investments [Line Items]
Cost		1,907
Fair Value		3,257
Equity | Containers & Packaging
Schedule of Investments [Line Items]
Cost		2,791
Fair Value		1,722
Equity | Distributors
Schedule of Investments [Line Items]
Cost		0
Fair Value		0
Equity | Diversified Consumer Services
Schedule of Investments [Line Items]
Cost		1,303
Fair Value		1,258
Equity | Electrical Equipment
Schedule of Investments [Line Items]
Cost		150
Fair Value		150
Equity | Food Products
Schedule of Investments [Line Items]
Cost		2,013
Fair Value		1,028
Equity | Health Care Providers & Services
Schedule of Investments [Line Items]
Cost		4,955
Fair Value		4,910
Equity | Insurance Services
Schedule of Investments [Line Items]
Cost		4,704
Fair Value		4,727
Equity | IT Services
Schedule of Investments [Line Items]
Cost		13,882
Fair Value		18,845
Equity | Professional Services
Schedule of Investments [Line Items]
Cost		3,492
Fair Value		2,149
Equity | Software
Schedule of Investments [Line Items]
Cost		16,045
Fair Value		$ 16,666

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