Document and Entity Information - shares	3 Months Ended
	Mar. 30, 2019	May 03, 2019
Document And Entity Information [Abstract]
Entity Registrant Name	SunOpta Inc.
Entity Central Index Key	0000351834
Trading Symbol	stkl
Current Fiscal Year End Date	--12-28
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		87,584,158
Document Type	10-Q
Document Period End Date	Mar. 30, 2019
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Small Business	false
Entity Emerging Growth Company	false