Document And Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Apr. 15, 2019	Jun. 30, 2018
Document And Entity Information
Entity Registrant Name	MGT CAPITAL INVESTMENTS, INC.
Entity Central Index Key	0001001601
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Public Float			$ 49,154,105
Entity Common Stock, Shares Outstanding		195,770,183
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2018