Quarterly report [Sections 13 or 15(d)]

RELATED PARTY TRANSACTIONS - Narrative (Details)

v3.25.4
RELATED PARTY TRANSACTIONS - Narrative (Details) - USD ($)
 3 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Sep. 30, 2025
Related Party Transaction [Line Items]      
Base management fee 1.75% 1.75%  
Base management fee, percent fee 100.00%    
Management and service fee, net of credit   0.50%  
Management and service fees, loans 1.50%    
Ratio of net investment income (loss) to average net assets – annualized 6.22% 5.61%  
Incentive fee base on minimum rate of return required on investment $ 0    
Percentage of pre-incentive fee net investment income is less than the hurdle rate 100.00%    
Investment company, pre-incentive fee net investment income, percent threshold of net assets 2.1875%    
Pre-incentive fee net investment income exceeds the hurdle rate 20.00%    
Investment company, capital gains-based incentive fees 20.00%    
Capital gains-based incentive fee $ 0    
Investment company, net investment income to common stockholder distributions ratio, threshold   100.00%  
Investment company, other operating expenses, due to advisor $ 100,000   $ 100,000
Gladstone Securities      
Related Party Transaction [Line Items]      
Selling commissions, percentage 7.00%    
Dealer manager fees percentage 3.00%    
Payments for selling commissions and dealer-manager fees $ 1,100,000 $ 300,000  
Related Party      
Related Party Transaction [Line Items]      
Success fee income 100,000 $ 200,000  
Fees due to related party 4,138,000   3,531,000
Related Party | Gladstone Investment Corporation      
Related Party Transaction [Line Items]      
Fees due to related party $ 54,000   $ 52,000
Total fees due to Adviser | Chief Executive Officer | Related Party      
Related Party Transaction [Line Items]      
Noncontrolling interest, ownership percentage by parent 100.00%    
Fee due to Administrator | Chief Executive Officer | Related Party      
Related Party Transaction [Line Items]      
Noncontrolling interest, ownership percentage by parent 100.00%    
Gladstone Securities, LLC | Chief Executive Officer | Related Party      
Related Party Transaction [Line Items]      
Noncontrolling interest, ownership percentage by parent 100.00%    
Maximum      
Related Party Transaction [Line Items]      
Base management fee 1.75%    
Minimum      
Related Party Transaction [Line Items]      
Ratio of net investment income (loss) to average net assets – annualized 1.75%