Annual report [Section 13 and 15(d), not S-K Item 405]

Investments - Schedule of Realized Gains and Losses and Changes in Unrealized Appreciation and Depreciation on Control and Affiliate investments (Details)

v3.25.4
Investments - Schedule of Realized Gains and Losses and Changes in Unrealized Appreciation and Depreciation on Control and Affiliate investments (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Schedule Of Investments [Line Items]      
Investments, at fair value: $ 4,466,647 $ 3,659,978  
Interest & Dividend Income 507,887 467,195 $ 434,425
Fee Income 24,606 26,396 26,243
Total net change in unrealized appreciation (depreciation) 38,812 (31,209) 25,010
Control investments      
Schedule Of Investments [Line Items]      
Investments, at fair value: 115,051 113,179 115,004
Interest & Dividend Income 13,817 13,403  
Interest Income     4,642
Fee Income 169 146 95
Total net change in unrealized appreciation (depreciation) 1,379 (3,559) 22,634
Net realized gain (loss) 0 0 0
Control investments | Coronado Aesthetics, LLC      
Schedule Of Investments [Line Items]      
Investments, at fair value: 218 69 262
Interest & Dividend Income 0 0  
Interest Income     0
Fee Income 0 0 0
Total net change in unrealized appreciation (depreciation) 149 (193) (57)
Net realized gain (loss) 0 0 0
Control investments | Gibraltar Acquisition LLC      
Schedule Of Investments [Line Items]      
Investments, at fair value: 62,218 59,263 62,512
Interest & Dividend Income 4,927 5,301  
Interest Income     3,344
Fee Income 169 146 95
Total net change in unrealized appreciation (depreciation) 2,462 (4,983) 9,656
Net realized gain (loss) 0 0 0
Control investments | Hercules Adviser LLC(3)      
Schedule Of Investments [Line Items]      
Investments, at fair value: 43,274 42,190 40,713
Interest & Dividend Income 8,200 7,410  
Interest Income     608
Fee Income 0 0 0
Total net change in unrealized appreciation (depreciation) 1,084 1,477 9,560
Net realized gain (loss) 0 0 0
Control investments | Tectura Corporation      
Schedule Of Investments [Line Items]      
Investments, at fair value: 9,341 11,657 11,517
Interest & Dividend Income 690 692  
Interest Income     690
Fee Income 0 0 0
Total net change in unrealized appreciation (depreciation) (2,316) 140 3,475
Net realized gain (loss) $ 0 $ 0 $ 0