Quarterly report [Sections 13 or 15(d)]

RELATED-PARTY TRANSACTIONS - Schedule of Management Fees, Incentive Fees and Associated Credits and Administration Fees (Details)

v3.25.3
RELATED-PARTY TRANSACTIONS - Schedule of Management Fees, Incentive Fees and Associated Credits and Administration Fees (Details) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2025
Sep. 30, 2024
Sep. 30, 2025
Sep. 30, 2024
Adviser        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities $ 1,992 $ 2,070 $ 6,040 $ 6,303
Base management fee | Adviser        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 1,992 2,070 6,040 6,303
Incentive fee | Adviser        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 0 109 0 109
Incentive fee waiver | Adviser        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 0 (109) 0 (109)
Administration fee        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 650 683 1,863 1,839
Total fees to Gladstone Securities | Gladstone Securities        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 0 9 15 39
Selling Commissions and Dealer Management Fees | Gladstone Securities        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 0 9 0 39
Financing fees        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities 0 0 15 0
Financing fees | Gladstone Securities        
Related Party Transaction [Line Items]        
Total fees to Gladstone Securities $ 0 $ 0 $ 15 $ 0