CONDENSED CONSOLIDATED INTERIM STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (unaudited) - USD ($) $ in Thousands	Total	New England Cannabis Corporation	Island Global Holdings, Inc.	Bloom	Total 4Front Ventures Corp. Shareholders' Equity (Deficit)	Total 4Front Ventures Corp. Shareholders' Equity (Deficit) New England Cannabis Corporation	Total 4Front Ventures Corp. Shareholders' Equity (Deficit) Island Global Holdings, Inc.	Total 4Front Ventures Corp. Shareholders' Equity (Deficit) Bloom	Share Capital	Share Capital New England Cannabis Corporation	Share Capital Island Global Holdings, Inc.	Share Capital Bloom	Additional Paid-In Capital	Deficit	Non-Controlling Interest
Beginning balance (in shares) at Dec. 31, 2021									594,181,604
Beginning balance at Dec. 31, 2021	$ 37,532				$ 37,460				$ 274,120				$ 52,197	$ (288,857)	$ 72
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for pursuant to acquisition (in shares)										28,571,428
Shares issued for pursuant to acquisition		$ 18,200				$ 18,200				$ 18,200
Share-based compensation	1,038				1,038								1,038
Conversion of notes to equity (in shares)									6,235,512
Conversion of notes to equity	3,122				3,122				$ 3,122
Shares issued with exercise of warrants (in shares)									88,659
Shares issued with exercise of warrants	50				50				$ 50
Net loss	(5,894)				(5,899)									(5,899)	5
Ending balance (in shares) at Mar. 31, 2022									629,077,203
Ending balance at Mar. 31, 2022	54,048				53,971				$ 295,492				53,235	(294,756)	77
Beginning balance (in shares) at Dec. 31, 2021									594,181,604
Beginning balance at Dec. 31, 2021	37,532				37,460				$ 274,120				52,197	(288,857)	72
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(21,041)
Ending balance (in shares) at Sep. 30, 2022									641,662,894
Ending balance at Sep. 30, 2022	49,263				49,176				$ 304,602				54,487	(309,913)	87
Beginning balance (in shares) at Mar. 31, 2022									629,077,203
Beginning balance at Mar. 31, 2022	54,048				53,971				$ 295,492				53,235	(294,756)	77
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for pursuant to acquisition (in shares)											8,783,716
Shares issued for pursuant to acquisition			$ 6,245				$ 6,245				$ 6,245
Share-based compensation	390				390								390
Warrants issued for Island pursuant to acquisition	732				732				$ 732
Shares issued with exercise of stock options (in shares)									51,975
Shares issued with exercise of stock options	33				33				$ 33
Net loss	(6,546)				(6,551)									(6,551)	5
Ending balance (in shares) at Jun. 30, 2022									637,912,894
Ending balance at Jun. 30, 2022	54,902				54,820				$ 302,502				53,625	(301,307)	82
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for pursuant to acquisition (in shares)												3,750,000
Shares issued for pursuant to acquisition				$ 2,100				$ 2,100				$ 2,100
Share-based compensation	862				862								862
Net loss	(8,601)				(8,606)									(8,606)	5
Ending balance (in shares) at Sep. 30, 2022									641,662,894
Ending balance at Sep. 30, 2022	$ 49,263				49,176				$ 304,602				54,487	(309,913)	87
Beginning balance (in shares) at Dec. 31, 2022	643,416,275								643,416,275
Beginning balance at Dec. 31, 2022	$ 28,351				28,258				$ 304,602				59,411	(335,755)	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation	1,020				1,020								1,020
Net loss	(11,392)				(11,397)									(11,397)	5
Ending balance (in shares) at Mar. 31, 2023									643,416,275
Ending balance at Mar. 31, 2023	$ 17,979				17,881				$ 304,602				60,431	(347,152)	98
Beginning balance (in shares) at Dec. 31, 2022	643,416,275								643,416,275
Beginning balance at Dec. 31, 2022	$ 28,351				28,258				$ 304,602				59,411	(335,755)	93
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued to settle payables (in shares)	15,743,702
Net loss	$ (84,952)
Ending balance (in shares) at Sep. 30, 2023	659,159,977								659,159,977
Ending balance at Sep. 30, 2023	$ (50,592)				(50,700)				$ 306,561				63,461	(420,722)	108
Beginning balance (in shares) at Mar. 31, 2023									643,416,275
Beginning balance at Mar. 31, 2023	17,979				17,881				$ 304,602				60,431	(347,152)	98
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares issued for pursuant to acquisition (in shares)									2,380,952
Shares issued for pursuant to acquisition	447				447				$ 447
Share-based compensation	214				214								214
Shares issued to settle payables (in shares)									4,062,500
Shares issued to settle payables	650				650				$ 650
Net loss	(11,464)				(11,469)									(11,469)	5
Ending balance (in shares) at Jun. 30, 2023									649,859,727
Ending balance at Jun. 30, 2023	7,826				7,723				$ 305,699				60,645	(358,621)	103
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based compensation (in shares)									0
Share-based compensation	2,634				2,634								2,634
Warrants issued	182				182								182
Shares issued for executive compensation (in shares)									9,300,250
Shares issued for executive compensation	862				862				$ 862
Net loss	$ (62,096)				(62,101)									(62,101)	5
Ending balance (in shares) at Sep. 30, 2023	659,159,977								659,159,977
Ending balance at Sep. 30, 2023	$ (50,592)				$ (50,700)				$ 306,561				$ 63,461	$ (420,722)	$ 108