Condensed Consolidated Statement of Changes in Stockholders' (Deficit) Equity (Unaudited) - USD ($) $ in Thousands	Preferred Stock [Member]	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 - employee restricted stock		$ 1	1,086			1,087		1,087
Stock-based compensation - employee restricted stock, shares		850,000
Forfeiture of employee restricted stock
Forfeiture of employee restricted stock, shares
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
Issuance of common stock for prior year sale
Issuance of common stock for prior year sale, shares
Exercise of warrants		$ 2	279			281		281
Exercise of warrants, shares		2,224,250
Stock issued in disposition of cybersecurity assets			120			120		120
Stock issued in disposition of cybersecurity 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, 2017		$ 59	390,736		(378,900)	11,895	(22)	11,873
Balance, shares at Dec. 31, 2017		58,963,009
Warrant modification expense								139
Net loss								(11,054)
Balance at Jun. 30, 2018		$ 71	398,300		(392,468)	5,903	(22)	5,881
Balance, shares at Jun. 30, 2018		71,757,626
Balance at Mar. 31, 2018		$ 66	395,789		(385,963)	9,892	(22)	9,870
Balance, shares at Mar. 31, 2018		66,127,626
Stock-based compensation - employee restricted stock		$ 1	1,248			1,249		1,249
Stock-based compensation - employee restricted stock, shares		1,500,000
Forfeiture of employee restricted stock		$ (1)	(232)			(233)		(233)
Forfeiture of employee restricted stock, shares		(550,000)
Stock issued for services			875			875		875
Stock issued for services, shares		730,000
Stock issued for prior year notes payable conversion
Stock issued for prior year notes payable conversion, shares
Stock sold in connection with private placements
Stock sold in connection with private placements, shares
Issuance of common stock for prior year sale		$ 1	(1)
Issuance of common stock for prior year sale, shares		750,000
Exercise of warrants		$ 4	621			625		625
Exercise of warrants, shares		3,200,000
Stock issued in disposition of cybersecurity assets
Stock issued in disposition of cybersecurity assets, shares
Warrant modification expense
Deemed dividend
Net loss					(6,505)	(6,505)		(6,505)
Balance at Jun. 30, 2018		$ 71	398,300		(392,468)	5,903	(22)	5,881
Balance, shares at Jun. 30, 2018		71,757,626
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 based compensation, shares
Stock issued for services - employee restricted stock			60			60		60
Stock issued for services - employee restricted stock, shares		160,500
Sale of stock under equity purchase agreement		$ 43	2,111	(346)		1,808		1,808
Sale of stock under 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
Balance at Dec. 31, 2018		$ 111	403,299		(404,719)	(1,309)		$ (1,309)
Balance, shares at Dec. 31, 2018		111,079,683
Issuance of common stock for prior year sale, shares								43,100,000
Warrant modification expense
Cumulative effect adjustment related to ASU adoption								3
Net loss								(5,328)
Balance at Jun. 30, 2019		$ 271	413,694		(411,003)	2,962		2,962
Balance, shares at Jun. 30, 2019	140	270,957,766
Balance at Mar. 31, 2019		$ 154	406,364	(346)	(406,425)	(253)		(253)
Balance, shares at Mar. 31, 2019		154,340,183
Stock-based compensation - employee restricted stock			730			730		730
Stock-based compensation - employee restricted stock, shares
Stock issued for services
Exercise of warrants		$ 4	116			120		120
Exercise of warrants, shares		4,000,000
Deemed dividend			959		(959)
Sale of stock under equity purchase agreement		$ 24	1,502	346		1,872		1,872
Sale of stock under equity purchase agreement, shares		23,900,000
Common stock issued on conversion of notes payable		$ 57	1,640			1,697		1,697
Common stock issued on conversion of notes payable		57,224,243
Stock sold in connection with registered direct placements		$ 18	507			525		525
Stock sold in connection with registered direct placements, shares		17,500,000
Sale of preferred stock			1,890			1,890		1,890
Sale of preferred stock, shares	190
Conversion of preferred stock		$ 14	(14)
Conversion of preferred stock, shares	(50)	13,993,340
Adoption of ASC 842
Net loss					(3,619)	(3,619)		(3,619)
Balance at Jun. 30, 2019		$ 271	$ 413,694		$ (411,003)	$ 2,962		$ 2,962
Balance, shares at Jun. 30, 2019	140	270,957,766