Document And Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 17, 2019
Document And Entity Information
Entity Registrant Name	MGT CAPITAL INVESTMENTS, INC.
Entity Central Index Key	0001001601
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business Flag	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Entity Common Stock, Shares Outstanding		218,687,983
Trading Symbol	MGTI
Document Fiscal Period Focus	Q1
Document Fiscal Year Focus	2019