v3.26.1
Financial Highlights (Details)
$ / shares in Units, € in Thousands, £ in Thousands, $ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2026
USD ($)
$ / shares
shares
Jun. 30, 2025
USD ($)
$ / shares
Jun. 30, 2026
USD ($)
$ / shares
shares
Jun. 30, 2025
USD ($)
$ / shares
shares
Jun. 30, 2026
EUR (€)
shares
Jun. 30, 2026
GBP (£)
shares
Dec. 31, 2025
USD ($)
shares
Dec. 31, 2025
EUR (€)
shares
Dec. 31, 2025
GBP (£)
shares
Jun. 30, 2025
EUR (€)
shares
Jun. 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     0.56 0.64              
Net realized and unrealized losses (in dollars per share) | $ / shares     (0.92) (0.36)              
Total net (decrease) increase (in dollars per share) | $ / shares     (0.36) 0.28              
Repurchase of common stock (in dollars per share) | $ / shares     0.30 0.02              
Distributions declared to stockholders from net investment income (in dollars per share) | $ / shares     (0.57) (0.64)              
Net asset value, ending balance (in dollars per share) | $ / shares $ 10.89 $ 12.21 10.89 12.21              
Per share market value (in dollars per share) | $ / shares $ 7.17 $ 10.55 $ 7.17 $ 10.55              
Total return based on market value     (16.11%) (0.72%)              
Total return based on net asset value     (0.50%) 2.44%              
Shares outstanding at end of period (in shares) | shares 94,452,390   94,452,390   94,452,390 94,452,390 102,638,388 102,638,388 102,638,388 106,926,713 106,926,713
Average weighted shares outstanding for the period (in shares) | shares     97,497,589 107,800,508              
Average net assets for the period | $     $ 1,099,108 $ 1,347,006              
Ratio to average net assets:                      
Net investment income     10.09% 10.33%              
Total expenses, before waivers/reimbursements     15.15% 15.62%              
Total expenses, net of waivers/reimbursements     13.76% 14.96%              
Asset coverage ratio 186.22%   186.22%   186.22% 186.22%       185.56% 185.56%
Portfolio turnover     7.55% 7.94%              
Accretive effect of common stock issuances per share (in dollars per share) | $ / shares     $ (0.01) $ 0.00              
Holdings Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance | $ $ 378,146   $ 378,146       $ 420,063        
NMFC Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance | $ 30,356   30,356       81,074        
Revolving Credit Facility | Holdings Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance | $ 378,146   378,146       420,063        
Revolving Credit Facility | NMFC Credit Facility                      
Ratio to average net assets:                      
Credit facility outstanding balance 30,356   30,356   € 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 $ 990,000 822,044 $ 990,000              
Line of Credit | Revolving Credit Facility | Holdings Credit Facility                      
Ratio to average net assets:                      
Average debt outstanding | $ 376,974 251,167 418,304 280,737              
Line of Credit | Revolving Credit Facility | NMFC Credit Facility                      
Ratio to average net assets:                      
Average debt outstanding | $ 30,824 30,315 72,131 29,314              
SBA-guaranteed debentures                      
Ratio to average net assets:                      
Average debt outstanding | $ $ 169,255 262,500 178,040 274,724              
Convertible Notes                      
Ratio to average net assets:                      
Average debt outstanding | $   $ 258,784 $ 0 $ 259,147