Document And Entity Information - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Mar. 30, 2018	Jun. 30, 2017
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, 2017
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	Smaller Reporting Company
Entity Public Float			$ 47,597,959
Entity Common Stock, Shares Outstanding		66,073,075
Trading Symbol	MGT
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2017