Quarterly report [Sections 13 or 15(d)]

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

v3.25.3
Investments - Schedule of Realized Gains and Losses and Changes in Unrealized Appreciation and Depreciation on Control and Affiliate investments (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2025
Sep. 30, 2024
Dec. 31, 2024
Dec. 31, 2023
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) $ 4,306,154   $ 4,306,154   $ 3,659,978  
Interest & Dividend Income 131,157 $ 119,050 376,300 $ 352,358    
Fee Income 6,936 6,198 18,763 19,449    
Net Change in Unrealized Appreciation (Depreciation) 32,989 (13,894) 55,214 (44,982)    
Control investments            
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) 112,323 113,097 112,323 113,097 $ 113,179 $ 115,004
Interest & Dividend Income 3,397 3,487 10,402 9,901    
Fee Income 44 36 124 108    
Net Change in Unrealized Appreciation (Depreciation) (2,541) 1,273 (1,400) (3,062)    
Realized Gain (Loss) 0 0 0 0    
Control investments | Coronado Aesthetics, LLC            
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) 344 319 344 319    
Interest & Dividend Income 0 0 0 0    
Fee Income 0 0 0 0    
Net Change in Unrealized Appreciation (Depreciation) 31 133 275 57    
Realized Gain (Loss) 0 0 0 0    
Control investments | Gibraltar Business Capital, LLC            
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) 60,193 57,302 60,193 57,302    
Interest & Dividend Income 1,123 1,359 3,786 3,926    
Fee Income 44 36 124 108    
Net Change in Unrealized Appreciation (Depreciation) (118) (74) 386 (6,365)    
Realized Gain (Loss) 0 0 0 0    
Control investments | Hercules Adviser LLC            
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) 43,510 43,433 43,510 43,433    
Interest & Dividend Income 2,100 1,954 6,100 5,457    
Fee Income 0 0 0 0    
Net Change in Unrealized Appreciation (Depreciation) (712) 705 1,320 2,720    
Realized Gain (Loss) 0 0 0 0    
Control investments | Tectura Corporation            
Schedule Of Investments [Line Items]            
Fair value of investments (in millions) 8,276 12,043 8,276 12,043    
Interest & Dividend Income 174 174 516 518    
Fee Income 0 0 0 0    
Net Change in Unrealized Appreciation (Depreciation) (1,742) 509 (3,381) 526    
Realized Gain (Loss) $ 0 $ 0 $ 0 $ 0