Cover Page - shares	6 Months Ended
	Jun. 30, 2022	Aug. 15, 2022
Document Information [Line Items]
Entity Registrant Name	4Front Ventures Corp.
Document Type	10-Q
Current Fiscal Year End Date	--12-31
Amendment Flag	false
Entity Central Index Key	0001783875
Entity Current Reporting Status	Yes
Entity Filer Category	Non-accelerated Filer
Document Period End Date	Jun. 30, 2022
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q2
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Shell Company	false
Entity Ex Transition Period	false
Document Quarterly Report	true
Document Transition Report	false
Entity File Number	000-56075
Entity Incorporation, State or Country Code	A1
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding		636,636,686
Entity Address, Address Line One	5060 N. 40th Street
Entity Address, Address Line Two	Suite 120
Entity Address, City or Town	Phoenix
Entity Address, State or Province	AZ
Entity Address, Postal Zip Code	85018
City Area Code	602
Local Phone Number	633-3067
Entity Tax Identification Number	83-4168417
Class A Subordinate Voting Share [Member]
Document Information [Line Items]
Trading Symbol	FFNTF
Security Exchange Name	NONE
Title of 12(b) Security	Class A Subordinate Voting Shares, no par value
ADR [Member]
Document Information [Line Items]
Trading Symbol	FFNT
Security Exchange Name	NONE
Title of 12(b) Security	Class A Subordinate Voting Shares, no par value