Commitments and Contingencies (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018
Loss Contingencies [Line Items]
Letters of Credit Outstanding, Amount	$ 10.7	$ 10.9
Product Recall [Member]
Loss Contingencies [Line Items]
Loss Contingency Damages Sought	On November 20, 2017, Treehouse Foods, Inc., several of its related entities, and its insurer filed a lawsuit against the Company in the Circuit Court of Cook County, Illinois titled Treehouse Foods, Inc. et al. v. SunOpta Grains and Food, Inc.  The Company was served with the Summons and Complaint on January 24, 2018.  After the Company removed the case to the United States District Court for the Northern District of Illinois, the plaintiffs filed an Amended Complaint on April 23, 2018 and a second Amended Complaint on October 12, 2018.  The plaintiffs allege economic damages resulting from the Company's 2016 voluntary recall of certain roasted sunflower kernel products due to the potential for listeria monocytogenes contamination.  The plaintiffs brought claims for breach of contract, express and implied warranties and product guarantees, negligence, strict liability, negligent misrepresentation, and indemnity seeking $16.2 million in damages.  There are no allegations of personal injury.  On March 29, 2019, the court dismissed the plaintiffs' claims for negligence, strict liability, negligent misrepresentation, and common law indemnity.  The Company is vigorously defending itself against the remaining contract and warranty-based claims.  The Company cannot reasonably predict the outcome of this claim, nor can it estimate the amount of loss, or range of loss, if any, that may result from this claim.
Loss Contingency Damages Sought Value	$ 16.2