v3.26.3
Financial Highlights (Details)
$ / shares in Units, € in Thousands, £ in Thousands, $ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2026
USD ($)
$ / shares
shares
Sep. 30, 2025
USD ($)
$ / shares
Sep. 30, 2026
USD ($)
$ / shares
shares
Sep. 30, 2025
USD ($)
$ / shares
shares
Sep. 30, 2026
EUR (€)
shares
Sep. 30, 2026
GBP (£)
shares
Dec. 31, 2025
USD ($)
shares
Dec. 31, 2025
EUR (€)
shares
Dec. 31, 2025
GBP (£)
shares
Sep. 30, 2025
EUR (€)
shares
Sep. 30, 2025
GBP (£)
shares
Investment Company, Financial Highlights [Roll Forward]                      
Net asset value, beginning balance (in dollars per share) | $ / shares     $ 11.52 $ 12.55              
Net investment income (in dollars per share) | $ / shares     0.81 0.96              
Net realized and unrealized losses (in dollars per share) | $ / shares     (1.12) (0.56)              
Total net (decrease) increase (in dollars per share) | $ / shares     (0.31) 0.40              
Repurchase of common stock (in dollars per share) | $ / shares     0.28 0.07              
Distributions declared to stockholders from net investment income (in dollars per share) | $ / shares     (0.82) (0.96)              
Net asset value, ending balance (in dollars per share) | $ / shares $ 10.67 $ 12.06 10.67 12.06              
Per share market value (in dollars per share) | $ / shares $ 6.92 $ 9.64 $ 6.92 $ 9.64              
Total return based on market value     (16.15%) (6.24%)              
Total return based on net asset value     (0.17%) 3.86%              
Shares outstanding at end of period (in shares) | shares 94,452,390   94,452,390   94,452,390 94,452,390 102,638,388 102,638,388 102,638,388 104,189,336 104,189,336
Average weighted shares outstanding for the period (in shares) | shares     96,471,368 107,199,318              
Average net assets for the period     $ 1,075,132 $ 1,329,882              
Ratio to average net assets:                      
Net investment income     9.77% 10.35%              
Total expenses, before waivers/reimbursements     15.00% 15.62%              
Total expenses, net of waivers/reimbursements     13.89% 14.72%              
Asset coverage ratio 184.03%   184.03%   184.03% 184.03%       179.09% 179.09%
Portfolio turnover     8.39% 12.18%              
Holdings Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance $ 391,446   $ 391,446       $ 420,063        
NMFC Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance 30,212   30,212       81,074        
Revolving Credit Facility | Holdings Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance 391,446   391,446       420,063        
Revolving Credit Facility | NMFC Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance 30,212   30,212   € 16,512 £ 8,666 $ 81,074 € 16,512 £ 8,666 € 16,512 £ 8,666
Unsecured Notes                      
Ratio to average net assets:                      
Average debt outstanding 790,000 $ 990,000 811,245 $ 990,000              
Line of Credit | Revolving Credit Facility | Holdings Credit Facility                      
Ratio to average net assets:                      
Average debt outstanding 359,174 293,932 398,377 285,184              
Line of Credit | Revolving Credit Facility | NMFC Credit Facility                      
Ratio to average net assets:                      
Average debt outstanding 30,658 30,991 58,155 29,879              
SBA-guaranteed debentures                      
Ratio to average net assets:                      
Average debt outstanding $ 153,194 240,882 169,667 263,319              
Convertible Notes                      
Ratio to average net assets:                      
Average debt outstanding   $ 258,777 $ 0 $ 259,022