Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2018	Feb. 22, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Document Period End Date	Dec. 29, 2018
Amendment Flag	false
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Entity Registrant Name	SunOpta Inc.
Entity Central Index Key	0000351834
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Current Fiscal Year End Date	--12-29
Entity Filer Category	Large Accelerated Filer
Entity Well Known Seasoned Issuer	Yes
Trading Symbol	STKL
Entity Public Float			$ 600
Entity Common Stock Shares Outstanding		87,478,618
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	false