Consolidated Statement of Changes in Stockholders' (Deficit) Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive Loss [Member]	Total (Deficit) Equity Attributable to MGT Stockholders [Member]	Non-controlling Interest [Member]	Total
Balance at Dec. 31, 2016	$ 29	$ 327,943	$ (328,467)	$ (66)	$ (561)	$ (22)	$ (583)
Balance, shares at Dec. 31, 2016	28,722,855
Stock-based compensation	$ 4	3,276			3,280		3,280
Stock-based compensation, shares	4,050,000
Stock issued for acquisition	$ 2	2,498			2,500		2,500
Stock issued for acquisition, shares	2,000,000
Stock issued for services	$ 3	4,626			4,629		4,629
Stock issued for services, shares	2,574,000
Stock issued in exchange of notes payables	$ 10	8,670			8,680		8,680
Stock issued in exchange of notes payables, shares	10,191,466
Induced conversion of notes payable		20,312			20,312		20,312
Sale of stock in connection with private placement	$ 3	9,147			9,150		9,150
Sale of stock in connection with private placement, shares	2,875,000
Beneficial conversion features on convertible notes		4,593			4,593		4,593
Stock issued in exchange of accounts payable		401			401		401
Stock issued in exchange of accounts payable, shares	220,000
Sale of common stock warrants		100			100		100
Stock issued in connection with notes payable amendment		118			118		118
Stock issued in connection with notes payable amendment, shares	200,000
Exercise of warrants	$ 8	387			395		395
Exercise of warrants, shares	7,693,588
Amortization of employee stock options		7,057			7,057		7,057
Modification of employee stock options		37			37		37
Stock and warrants issued in connection with Management Agreements		1,571			1,571		1,571
Stock and warrants issued in connection with Management Agreements, shares	436,100
Net loss			(50,433)		(50,433)		(50,433)
Reclassification adjustment for loss included in net loss				66	66		66
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	$ 3	4,354			4,357		4,357
Stock-based compensation, shares	2,860,000
Stock issued for services	$ 2	2,270			2,272		2,272
Stock issued for services, shares	2,387,273
Sale of stock in connection with private placement		80			80		80
Sale of stock in connection with private placement, shares	200,000
Exercise of warrants	$ 11	896			907		907
Exercise of warrants, shares	10,094,251
Forfeiture of unvested restricted stock	$ (1)	(232)			(233)		(233)
Forfeiture of unvested restricted stock, shares	(550,000)
Forfeiture of vested restricted stock	$ (2)	2
Forfeiture of vested restricted stock, shares	(1,966,666)
Stock issued for prior year notes payable conversion	$ 3	(3)
Stock issued for prior year notes payable conversion, shares	3,381,816
Sale of stock in connection with equity purchase agreement	$ 34	2,425			2,459		2,459
Sale of stock in connection with equity purchase agreement, shares	33,650,000
Issuance of common stock for prior year sale	$ 2	(2)
Issuance of common stock for prior year sale, shares	2,000,000
Stock issued in disposition of cybersecurity assets		120			120		120
Stock issued in disposition of cybersecurity assets, shares	60,000
Deemed dividend		2,514	(2,514)
Warrant modification expense		139			139		139
Reclassification of non-controlling interest to accumulated deficit			(22)		(22)	22
Net loss			(23,849)		(23,849)		(23,849)
Balance at Dec. 31, 2018	$ 111	$ 403,299	$ (405,285)		$ (1,875)		$ (1,875)
Balance, shares at Dec. 31, 2018	111,079,683