Condensed Consolidated Interim Statements of Changes in Shareholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Pure Ratios	Om of Medicine	Share Capital	Share Capital Pure Ratios	Share Capital Om of Medicine	Additional Paid-In Capital	Deficit	Total 4Front Ventures Corp. Shareholders' Equity	Total 4Front Ventures Corp. Shareholders' Equity Pure Ratios	Total 4Front Ventures Corp. Shareholders' Equity Om of Medicine	Non-Controlling Interest
Beginning Balance at Dec. 31, 2019	$ 74,760			$ 252,656			$ 25,618	$ (203,497)	$ 74,777			$ (17)
Beginning Balance, Shares at Dec. 31, 2019				531,522,819
Conversion option and warrants with notes transferred to equity	411						411		411
Shares issued for earnout		$ 94			$ 94					$ 94
Shares issued for earnout, shares					223,145
Share-based compensation	3,792						3,792		3,792
Conversion of notes to equity	2,887						2,887		2,887
Exchange of stock for convertible swap notes	(13,661)			$ (13,661)					(13,661)
Exchange of stock for convertible swap notes, shares				(29,775,670)
Shares issued with exercise of warrants and options	1,273			$ 1,273					1,273
Shares issued with exercise of warrants and options, shares				3,616,834
Purchase of non-controlling interests in Maryland entities	254											254
Net loss	(12,400)							(12,441)	(12,441)			41
Ending Balance at Sep. 30, 2020	57,410			$ 240,362			32,708	(215,938)	57,132			278
Ending Balance, Shares at Sep. 30, 2020				505,587,128
Beginning Balance at Dec. 31, 2020	42,203			$ 250,583			42,116	(250,548)	42,151			52
Beginning Balance, Shares at Dec. 31, 2020				538,851,252
Shares issued for earnout		$ 161	$ 722		$ 161	$ 722				$ 161	$ 722
Shares issued for earnout, shares					473,491	535,018
Share-based compensation	7,978						7,978		7,978
Conversion of notes to equity	17,719			$ 17,719					17,719
Shares issued with exercise of stock options	$ 1,316			$ 1,316					1,316
Shares issued with exercise of stock options, shares	2,032,983			2,032,983
Shares issued with exercise of warrants	$ 3,376			$ 3,376					3,376
Shares issued with exercise of warrants, shares				2,993,227
Return of treasury shares				(8,320)
Conversion of notes to equity, shares				49,042,797
Net loss	(21,896)							(21,911)	(21,911)			15
Ending Balance at Sep. 30, 2021	$ 51,579			$ 273,877			$ 50,094	$ (272,459)	$ 51,512			$ 67
Ending Balance, Shares at Sep. 30, 2021	593,920,448			593,920,448