Condensed Consolidated Statement of Changes in Stockholders' (Deficit) Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Subscription Receivable [Member]	Accumulated Deficit [Member]	Total (Deficit) Equity Attributable to MGT Stockholders [Member]	Non-controlling Interest [Member]	Total
Balance at Dec. 31, 2017	$ 59	$ 390,736		$ (378,900)	$ 11,895	$ (22)	$ 11,873
Balance, shares at Dec. 31, 2017	58,963,009
Stock-based compensation	$ 1	1,086			1,087		1,087
Stock-based compensation, shares	850,000
Stock issued for services	$ 1	838			839		839
Stock issued for services, shares	448,551
Stock issued for prior year notes payable conversion	$ 3	(3)
Stock issued for prior year notes payable conversion, shares	3,381,816
Stock sold in connection with private placements		80			80		80
Stock sold in connection with private placements,shares	200,000
Exercise of warrants	$ 2	279			281		281
Exercise of warrants, shares	2,224,250
Stock issued in disposition of cyber security assets		120			120		120
Stock issued in disposition of cyber security assets, shares	60,000
Warrant modification expense		139			139		139
Deemed dividend		2,514		(2,514)
Net loss				(4,549)	(4,549)		(4,549)
Balance at Mar. 31, 2018	$ 66	395,789		(385,963)	9,892	(22)	9,870
Balance, shares at Mar. 31, 2018	66,127,626
Balance at Dec. 31, 2018	$ 111	403,299		(404,719)	(1,309)		(1,309)
Balance, shares at Dec. 31, 2018	111,079,683
Stock-based compensation		894			894		894
Stock issued for services		60			60		60
Stock issued for services, shares	160,500
Warrant modification expense
Sale of stock in connection with equity purchase agreement	$ 43	2,111	(346)		1,808		1,808
Sale of stock in connection with equity purchase agreement, shares	43,100,000
Cumulative effect adjustment related to ASU adoption				3	3		3
Net loss				(1,709)	(1,709)		(1,709)
Balance at Mar. 31, 2019	$ 154	$ 406,364	$ (346)	$ (406,425)	$ (253)		$ (253)
Balance, shares at Mar. 31, 2019	154,340,183