Gladstone Investment Corporation Quarterly report [Sections 13 or 15(d)]

Quarterly report [Sections 13 or 15(d)]

BORROWINGS - Notes Payable (Narrative) (Details)

BORROWINGS - Notes Payable (Narrative) (Details) - USD ($) $ in Thousands		1 Months Ended
	May 01, 2026	Feb. 28, 2026	Nov. 30, 2025	Dec. 31, 2024	Aug. 31, 2021	Mar. 31, 2021	Jun. 30, 2026	Mar. 31, 2026	Jun. 30, 2025
Debt Instrument [Line Items]
Total borrowings, at cost at end of period							$ 578,650		$ 525,738
Notes Payable
Debt Instrument [Line Items]
Total borrowings, at cost at end of period							$ 421,050	$ 548,988
5.00% 2026 Notes \| Notes Payable
Debt Instrument [Line Items]
Interest rate	5.00%					5.00%		5.00%
Total borrowings, at cost at end of period						$ 127,900		$ 127,938
Proceeds from issuance of long-term debt						$ 123,800
Repayments of long-term debt	$ 127,900
Notes payable, fair value disclosure								$ 129,000
4.875% Notes due 2028 \| Notes Payable
Debt Instrument [Line Items]
Interest rate					4.875%		4.875%	4.875%
Total borrowings, at cost at end of period					$ 134,600		$ 134,550	$ 134,550
Proceeds from issuance of long-term debt					131,300
Borrowings outstanding at cost					$ 3,300
Notes payable, fair value disclosure							$ 128,000	$ 127,800
7.875% 2030 Notes \| Notes Payable
Debt Instrument [Line Items]
Interest rate				7.875%			7.875%	7.875%
Total borrowings, at cost at end of period				$ 126,500			$ 126,500	$ 126,500
Proceeds from issuance of long-term debt				122,400
Borrowings outstanding at cost				$ 4,100
Notes payable, fair value disclosure							$ 128,900	$ 128,200
6.875% 2028 Notes \| Notes Payable
Debt Instrument [Line Items]
Interest rate			6.875%				6.875%	6.875%
Total borrowings, at cost at end of period			$ 60,000				$ 60,000	$ 60,000
Proceeds from issuance of long-term debt			58,800
Borrowings outstanding at cost			$ 1,200
Notes payable, fair value disclosure							$ 59,400	$ 59,700
6.875% 2028 Notes \| Notes Payable \| Discount Rate
Debt Instrument [Line Items]
Debt instrument, measurement input							0.07350	0.07075
7.125% Notes due 2031 \| Notes Payable
Debt Instrument [Line Items]
Interest rate		7.125%					7.125%	7.125%
Total borrowings, at cost at end of period		$ 100,000					$ 100,000	$ 100,000
Proceeds from issuance of long-term debt		96,900
Borrowings outstanding at cost		$ 3,100
Notes payable, fair value disclosure							$ 99,700	$ 101,300