v3.26.1
Cover - USD ($)
 12 Months Ended
Dec. 31, 2025
Mar. 16, 2026
Jun. 30, 2025
Cover [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Annual Report true    
Document Transition Report false    
Document Period End Date Dec. 31, 2025    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2025    
Current Fiscal Year End Date --12-31    
Entity File Number 001-32698    
Entity Registrant Name MGT CAPITAL INVESTMENTS, INC.    
Entity Central Index Key 0001001601    
Entity Tax Identification Number 13-4148725    
Entity Incorporation, State or Country Code DE    
Entity Address, Address Line One 540 Montreal Ave    
Entity Address, Address Line Two Suite 133    
Entity Address, City or Town Melbourne    
Entity Address, State or Province FL    
Entity Address, Postal Zip Code 32935    
City Area Code (914)    
Local Phone Number 630–7430    
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 true    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 683,953
Entity Common Stock, Shares Outstanding   5,015,670,903  
Document Financial Statement Error Correction [Flag] false    
ICFR Auditor Attestation Flag false    
Entity Listing, Par Value Per Share $ 0.001    
Auditor Opinion [Text Block] We have audited the accompanying balance sheets of MGT Capital Investments, Inc. (the Company) as of December 31, 2025 and 2024, the related statements of operations, stockholders’ deficit and cash flows for each of the years in the two-year period ended December 31, 2025, and the related notes (collectively referred to as the financial statement). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the years in the two-year period ended December 31, 2025, in conformity with accounting principles generally accepted in the United States of America.    
Auditor Name RBSM LLP    
Auditor Location Larkspur, CA    
Auditor Firm ID 587