Consolidated Statements of Changes in Shareholders Equity - USD ($) $ in Thousands	Total	Advisors	LI Lending LLC	Cannex Capital Holdings Inc	Class F Units	Class F Units PHX Interactive LLC	Class F Units Om of Medicine LLC	Share Capital	Share Capital Cannex Capital Holdings Inc	Share Capital Class F Units	Share Capital Class F Units PHX Interactive LLC	Share Capital Class F Units Om of Medicine LLC	Share Capital Class F Units Cannex Capital Holdings Inc	Additional Paid-In Capital	Additional Paid-In Capital Advisors	Additional Paid-In Capital LI Lending LLC	Additional Paid-In Capital Cannex Capital Holdings Inc	Deficit	Total 4Front Ventures Corp. Shareholders' Equity	Total 4Front Ventures Corp. Shareholders' Equity Advisors	Total 4Front Ventures Corp. Shareholders' Equity LI Lending LLC	Total 4Front Ventures Corp. Shareholders' Equity Cannex Capital Holdings Inc	Total 4Front Ventures Corp. Shareholders' Equity Class F Units	Total 4Front Ventures Corp. Shareholders' Equity Class F Units PHX Interactive LLC	Total 4Front Ventures Corp. Shareholders' Equity Class F Units Om of Medicine LLC	Noncontrolling Interest
Beginning Balance at Dec. 31, 2018	$ 48,031							$ 68,959						$ 2,227				$ (21,487)	$ 49,699							$ (1,668)
Beginning balance, Number of units at Dec. 31, 2018								803,591
Class F Units of Holdings for Acquisition				$ 187,935		$ 2,676	$ 4,400		$ 181,110		$ 2,676	$ 4,400					$ 6,825					$ 187,935		$ 2,676	$ 4,400
Class F Units of Holdings for Acquisition, Units									190,482,146		5,496	9,040	3,901
Class F Units of Holdings for acquisition of non-controlling interests					$ 7,989					$ 7,989													$ 7,989
Class F Units of Holdings for acquisition of non-controlling interests, units										11,642
Purchase of non-controlling interests	(8,390)							$ (10,156)											(10,156)							1,766
Issuance of Class F units to brokers					$ 115					$ 115													$ 115
Insuance of Class F units to brokers, units										236
Share issuance costs	(115)							$ (115)											(115)
Share-based compensation through July 31, 2019	3,776													3,776					3,776
Share-based compensation through July 31, 2019, units								34,572
Conversion of 4Front Holdings units to 4Front Ventures Corp, units								(868,478)
Conversion of 4Front Holdings units to 4Front Ventures Corp, shares								340,370,271
GGP warrants acquired with Cannex	5,779													5,779					5,779
Issuance of broker warrants	1,823													1,823					1,823
Share issuance costs	(1,823)													(1,823)					(1,823)
Issuance of shares to brokers	420							$ 420											420
Issuance of shares to brokers, shares								1,035,456
Share issuance costs	(420)							$ (420)											(420)
Conversion option on GGP notes transferred to equity	4,874													4,874					4,874
Purchase of non-controlling interests in Arkansas entities	(2,322)							$ (2,322)											(2,322)
Share-based compensation after July 31, 2019	2,137													2,137					2,137
Return of treasury shares								(365,054)
Net loss	(182,125)																	(182,010)	(182,010)							(115)
Ending Balance at Dec. 31, 2019	74,760							$ 252,656						25,618				(203,497)	74,777							(17)
Ending Balance, Shares at Dec. 31, 2019								531,522,819
Conversion option and warrants with notes transferred to equity	411													411					411
Conversion option for convertible notes transferred to equity	5,163													5,163					5,163
Shares issued for Pure Ratios earnout	94							$ 94											94
Shares issued for Pure Ratios earnout, shares								223,145
Share-based compensation	5,306													5,306					5,306
Exchange of stock for convertible swap notes	(13,661)							$ (13,661)											(13,661)
Exchange of stock for convertible swap notes, shares								(29,448,468)
Conversion of notes to equity	1,939							$ 1,939											1,939
Conversion of notes to equity, shares								4,479,113
Shares issued with exercise of warrants	1,352							$ 1,352											1,352
Shares issued with exercise of warrants, shares								2,686,463
Shares issued for services	644							$ 644											644
Shares issued for services, shares								1,192,640
Issuance of stock for purchase of non-controlling interests								$ 231											231							(231)
Issuance of stock for purchase of non-controlling interests, shares								3,551,040
Derecognition of NCI with the sale of Maryland entities	254																									254
Issuance of stock for bought deal	8,018							$ 8,018											8,018
Issuance of stock for bought deal, shares								24,644,500
Share issuance costs for bought deal	(690)							$ (690)											(690)
Issuance of warrants		$ 381	$ 4,660												$ 381	$ 4,660				$ 381	$ 4,660
Issuance of broker warrants	577													577					577
Net loss	(47,005)																	(47,051)	(47,051)							46
Ending Balance at Dec. 31, 2020	$ 42,203							$ 250,583						$ 42,116				$ (250,548)	$ 42,151							$ 52
Ending Balance, Shares at Dec. 31, 2020	538,851,252							538,851,252