Document And Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Mar. 30, 2020	Jun. 30, 2019
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, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity's Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 20,550,962
Entity Common Stock, Shares Outstanding		446,448,445
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2019