Series A Preferred Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended
	Mar. 28, 2020	Mar. 30, 2019	Apr. 24, 2020
Temporary Equity [Line Items]
Preferred stock accretion to redemption value	$ 325	$ 295
Dividends, Preferred Stock, Paid-in-kind	$ 1,700	0
Series A Preferred Stock [Member] | Oaktree Organics, L.P. and Oaktree Huntington Investment Fund II, L.P.
Temporary Equity [Line Items]
Preferred Stock, Shares Issued	85,000		809,524
Preferred Stock, Value, Issued	$ 85,000
Preferred Stock Issuance Costs	6,000
Preferred Stock, Redemption Amount	85,000
Preferred stock accretion to redemption value	$ 300	$ 300
Preferred Stock, Dividend Preference or Restrictions	In connection with the Series A Subscription Agreement, the Company agreed to, among other things (i) ensure SunOpta Foods has sufficient funds to pay its obligations under the terms of the Series A Preferred Stock and (ii) grant each holder of Series A Preferred Stock the right to exchange the Series A Preferred Stock for shares of common stock of the Company (the "Common Shares").  The Series A Preferred Stock is non-participating with the Common Shares in dividends and undistributed earnings of the Company.
Preferred Stock, Liquidation Preference Per Share	$ 1,000
Preferred Stock Annualized Rate	8.00%
Preferred Stock, Dividend Payment Terms	Cumulative preferred dividends accrue daily on the Series A Preferred Stock at an annualized rate of 8.0% of the liquidation preference prior to October 5, 2025 and 12.5% of the liquidation preference thereafter (subject to an increase of 1.0% per quarter, up to a maximum rate of 5.0% per quarter on the occurrence of certain events of non-compliance).  Prior to October 5, 2025, SunOpta Foods may pay dividends in cash or elect, in lieu of paying cash, to add the amount that would have been paid to the liquidation preference.
Dividends, Preferred Stock, Paid-in-kind	$ 1,700
Convertible Preferred Stock, Terms of Conversion	At any time, the holders of Series A Preferred Stock may exchange their shares of Series A Preferred Stock, in whole or in part, into the number of Common Shares equal to, per share of Series A Preferred Stock, the quotient of the liquidation preference divided by $7.50 (such price, the “Series A Exchange Price” and such quotient, the “Series A Exchange Rate”). As at March 28, 2020 and December 28, 2019, the aggregate shares of Series A Preferred Stock outstanding were exchangeable into 11,333,333 Common Shares. The Series A Exchange Price is subject to certain anti-dilution adjustments, including a weighted-average adjustment for issuances of Common Shares below the Series A Exchange Price, provided that the Series A Exchange Price may not be lower than $7.00 (subject to adjustment in certain circumstances). On April 24, 2020, in connection with the issuance of Series B-1 Preferred Stock pursuant to the Series B Subscription Agreement (see note 14), the Series A Exchange Price was reduced from $7.50 to $7.00
Convertible Preferred Stock, Settlement Terms	SunOpta Foods may cause the holders of Series A Preferred Stock to exchange all of their shares of Series A Preferred Stock into a number of Common Shares equal to the number of shares of Series A Preferred Stock outstanding multiplied by the Series A Exchange Rate if (i) fewer than 10% of the shares of Series A Preferred Stock issued on October 7, 2016 remain outstanding, or (ii) on or after October 7, 2019, the average volume-weighted average price of the Common Shares during the then preceding 20 trading day period is greater than 200% of the Series A Exchange Price then in effect. At any time on or after October 7, 2021, SunOpta Foods may redeem all of the Series A Preferred Stock for an amount per share equal to the value of the liquidation preference of the Series A Preferred Stock at such time, plus accrued and unpaid dividends.
Preferred Stock, Voting Rights	In connection with the Series A Subscription Agreement, the Company issued 11,333,333 Special Shares, Series 1 to Oaktree, which entitles Oaktree to one vote per Special Share, Series 1 on all matters submitted to a vote of the holders of Common Shares, together as a single class, subject to certain exceptions. Additional Special Shares, Series 1 will be issued, or existing Special Shares, Series 1 will be redeemed, as necessary to ensure that the aggregate number of Special Shares, Series 1 outstanding is equal to the number of shares of Series A Preferred Stock outstanding from time to time multiplied by the Series A Exchange Rate in effect at such time.
Preferred Stock, Participation Rights	For so long as Oaktree beneficially own or control at least 50% of the Series A Preferred Stock issued on October 7, 2016, including any corresponding Common Shares into which such Series A Preferred Stock are exchanged, Oaktree will be entitled to (i) participation rights with respect to future equity offerings of the Company, and (ii) governance rights, including the right to approve certain actions proposed to be taken by the Company and its subsidiaries.
Special Voting Shares, issued and outstanding	11,333,333