Annual report pursuant to Section 13 and 15(d)

Cover

v3.23.1
Cover - USD ($)
 12 Months Ended
Mar. 31, 2023
May 09, 2023
Sep. 30, 2022
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Mar. 31, 2023    
Current Fiscal Year End Date --03-31    
Document Transition Report false    
Entity File Number 814-00704    
Entity Registrant Name GLADSTONE INVESTMENT CORPORATION\DE    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 83-0423116    
Entity Address, Address Line One 1521 WESTBRANCH DRIVE    
Entity Address, Address Line Two SUITE 100    
Entity Address, City or Town MCLEAN    
Entity Address, State or Province VA    
Entity Address, Postal Zip Code 22102    
City Area Code 703    
Local Phone Number 287-5800    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Non-accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag false    
Entity Shell Company false    
Entity Public Float     $ 390,435,779
Entity Common Stock, Shares Outstanding   33,591,505  
Documents Incorporated by Reference Portions of the Registrant’s definitive proxy statement relating to the Registrant’s 2023 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A are incorporated by reference into Part III of this Annual Report on Form 10-K as indicated herein. Such proxy statement will be filed with the Securities and Exchange Commission no later than 120 days following the end of the Registrant’s fiscal year ended March 31, 2023.    
Entity Central Index Key 0001321741    
Document Fiscal Year Focus 2023    
Document Fiscal Period Focus FY    
Amendment Flag false    
Common Stock, $0.001 par value per share      
Document Information [Line Items]      
Title of 12(b) Security Common Stock, $0.001 par value per share    
Trading Symbol GAIN    
Security Exchange Name NASDAQ    
2026 Notes      
Document Information [Line Items]      
Title of 12(b) Security 5.00% Notes due 2026    
Trading Symbol GAINN    
Security Exchange Name NASDAQ    
2028 Notes      
Document Information [Line Items]      
Title of 12(b) Security 4.875% Notes due 2028    
Trading Symbol GAINZ    
Security Exchange Name NASDAQ