v3.26.1
Investments - Schedule of Composition of the Company's Investment Portfolio by Industry, at Amortized Cost and Fair Value (with Corresponding Percentage of Total Portfolio Investments) (Details) - USD ($)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2026
Dec. 31, 2025
Investments    
Amortized cost $ 5,916,273 [1] $ 5,913,363 [2]
Fair value $ 5,804,557 [1],[3] $ 5,819,755 [2],[4]
Concentration risk, percentage   100.00%
Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 100.00%  
Investment Owned, At Cost | Geographic Concentration Risk    
Investments    
Concentration risk, percentage 100.00% 100.00%
Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 100.00% 100.00%
Investment Owned, At Fair Value | Geographic Concentration Risk    
Investments    
Concentration risk, percentage 100.00% 100.00%
Interest rate 0.10%  
Aerospace & Defense    
Investments    
Amortized cost $ 36,588 $ 41,610
Fair value $ 37,596 $ 40,434
Aerospace & Defense | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.60% 0.70%
Aerospace & Defense | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.60% 0.70%
Automotive    
Investments    
Amortized cost $ 125,059 $ 132,579
Fair value $ 52,590 $ 61,039
Automotive | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 2.10% 2.20%
Automotive | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.90% 1.00%
Banking    
Investments    
Amortized cost $ 46,982 $ 46,932
Fair value $ 40,681 $ 40,681
Banking | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.80% 0.80%
Banking | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.70% 0.70%
Beverage, Food & Tobacco    
Investments    
Amortized cost $ 146,101 $ 146,450
Fair value $ 146,773 $ 145,549
Beverage, Food & Tobacco | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 2.50% 2.50%
Beverage, Food & Tobacco | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 2.50% 2.50%
Capital Equipment    
Investments    
Amortized cost $ 209,527 $ 278,579
Fair value $ 201,387 $ 272,138
Capital Equipment | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 3.50% 4.70%
Capital Equipment | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 3.50% 4.70%
Chemicals, Plastics & Rubber    
Investments    
Amortized cost $ 53,788 $ 53,586
Fair value $ 54,436 $ 53,692
Chemicals, Plastics & Rubber | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.90% 0.90%
Chemicals, Plastics & Rubber | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.90% 0.90%
Construction & Building    
Investments    
Amortized cost $ 290,699 $ 275,448
Fair value $ 298,568 $ 282,687
Construction & Building | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 4.90% 4.70%
Construction & Building | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 5.10% 4.90%
Consumer Goods: Durable    
Investments    
Amortized cost $ 83,341 $ 87,104
Fair value $ 45,212 $ 54,861
Consumer Goods: Durable | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.40% 1.50%
Consumer Goods: Durable | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.80% 0.90%
Consumer Goods: Non-Durable    
Investments    
Amortized cost $ 85,306 $ 87,121
Fair value $ 77,918 $ 80,235
Consumer Goods: Non-Durable | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.40% 1.50%
Consumer Goods: Non-Durable | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.30% 1.40%
Containers, Packaging & Glass    
Investments    
Amortized cost $ 90,878 $ 57,824
Fair value $ 90,346 $ 57,516
Containers, Packaging & Glass | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.50% 1.00%
Containers, Packaging & Glass | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.60% 1.00%
Energy: Oil & Gas    
Investments    
Amortized cost $ 132 $ 132
Fair value $ 191 $ 133
Energy: Oil & Gas | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.00% 0.00%
Energy: Oil & Gas | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.00% 0.00%
Environmental Industries    
Investments    
Amortized cost $ 103,406 $ 101,103
Fair value $ 102,477 $ 100,594
Environmental Industries | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.80% 1.70%
Environmental Industries | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.80% 1.70%
FIRE: Finance    
Investments    
Amortized cost $ 386,713 $ 395,159
Fair value $ 394,126 $ 401,245
FIRE: Finance | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 6.50% 6.70%
FIRE: Finance | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 6.80% 6.90%
FIRE: Real Estate    
Investments    
Amortized cost $ 169,276 $ 170,649
Fair value $ 171,319 $ 173,367
FIRE: Real Estate | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 2.90% 2.90%
FIRE: Real Estate | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 3.00% 3.00%
Healthcare & Pharmaceuticals    
Investments    
Amortized cost $ 864,498 $ 831,390
Fair value $ 851,618 $ 822,082
Healthcare & Pharmaceuticals | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 14.60% 14.10%
Healthcare & Pharmaceuticals | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 14.70% 14.10%
High Tech Industries    
Investments    
Amortized cost $ 772,689 $ 765,255
Fair value $ 767,067 $ 768,219
High Tech Industries | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 13.10% 12.90%
High Tech Industries | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 13.20% 13.20%
Hotels, Gaming & Leisure    
Investments    
Amortized cost $ 95 $ 95
Fair value $ 304 $ 122
Hotels, Gaming & Leisure | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.00% 0.00%
Hotels, Gaming & Leisure | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.00% 0.00%
Media: Advertising, Printing & Publishing    
Investments    
Amortized cost $ 306,677 $ 327,320
Fair value $ 301,268 $ 324,332
Media: Advertising, Printing & Publishing | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 5.20% 5.40%
Media: Advertising, Printing & Publishing | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 5.20% 5.60%
Media: Broadcasting & Subscription    
Investments    
Amortized cost $ 3,448 $ 3,448
Fair value $ 474 $ 523
Media: Broadcasting & Subscription | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.10% 0.10%
Media: Broadcasting & Subscription | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.00% 0.00%
Media: Diversified & Production    
Investments    
Amortized cost $ 90,770 $ 92,892
Fair value $ 85,965 $ 88,577
Media: Diversified & Production | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.50% 1.50%
Media: Diversified & Production | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.50% 1.50%
Retail    
Investments    
Amortized cost $ 14,819 $ 14,448
Fair value $ 14,976 $ 14,624
Retail | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.30% 0.20%
Retail | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.30% 0.30%
Services: Business    
Investments    
Amortized cost $ 1,309,171 $ 1,276,711
Fair value $ 1,331,015 $ 1,299,308
Services: Business | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 22.10% 21.60%
Services: Business | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 22.90% 22.30%
Services: Consumer    
Investments    
Amortized cost $ 362,081 $ 341,755
Fair value $ 361,145 $ 338,841
Services: Consumer | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 6.10% 5.80%
Services: Consumer | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 6.20% 5.80%
Telecommunications    
Investments    
Amortized cost $ 85,791 $ 129,104
Fair value $ 80,952 $ 122,038
Telecommunications | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.50% 2.20%
Telecommunications | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 1.40% 2.10%
Transportation: Cargo    
Investments    
Amortized cost $ 225,437 $ 211,690
Fair value $ 210,656 $ 201,888
Transportation: Cargo | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 3.80% 3.60%
Transportation: Cargo | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 3.60% 3.50%
Utilities: Electric    
Investments    
Amortized cost $ 4,504 $ 4,504
Fair value $ 37,999 $ 36,030
Utilities: Electric | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.10% 0.10%
Utilities: Electric | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.70% 0.60%
Wholesale    
Investments    
Amortized cost $ 42,395 $ 40,475
Fair value $ 41,396 $ 39,000
Wholesale | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.70% 0.70%
Wholesale | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.70% 0.70%
Transportation Consumer Sector    
Investments    
Amortized cost $ 6,102 $ 0
Fair value $ 6,102 $ 0
Transportation Consumer Sector | Investment Owned, At Cost | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.10% 0.00%
Transportation Consumer Sector | Investment Owned, At Fair Value | Investment Portfolio By Industry Concentration Risk    
Investments    
Concentration risk, percentage 0.10% 0.00%
[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] 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.
[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).
[4] 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).