Series A Preferred Stock (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Dec. 30, 2017
Temporary Equity [Line Items]
Payment of cash dividends on Series A Preferred Stock	$ 6,800	$ 6,800	$ 6,691
Preferred stock accretion to redemption value	$ 1,222	1,109	1,009
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
Preferred Stock, Value, Issued	$ 85,000
Preferred Stock Issuance Costs	6,000
Preferred Stock, Redemption Amount	$ 85,000
Preferred Stock, Redemption Terms	At any time on or after October 7, 2021, SunOpta Foods may redeem all of the Preferred Stock for an amount, per share of Preferred Stock, equal to the value of the liquidation preference at such time. The carrying value of the Preferred Stock is being accreted to the redemption amount of $85.0 million through charges to accumulated deficit over the period preceding October 7, 2021.
Preferred Stock, Dividend Preference or Restrictions	In connection with the 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 Preferred Stock and (ii) grant each holder of Preferred Stock (the "Holder") the right to exchange the Preferred Stock for shares of common stock of the Company (the "Common Shares"). The 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 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. After October 4, 2025, the failure to pay dividends in cash will be an event of non-compliance. The Preferred Stock ranks senior to the shares of common stock of SunOpta Foods with respect to dividend rights and rights on the distribution of assets on any liquidation, winding up or dissolution of the Company or SunOpta Foods.
Accrued Unpaid Dividends	$ 1,700
Preferred stock accretion to redemption value	$ 1,200	$ 1,100	$ 1,000
Convertible Preferred Stock, Terms of Conversion	At any time, the Holders may exchange their shares of Preferred Stock, in whole or in part, into the number of Common Shares equal to, per share of Preferred Stock, the quotient of the liquidation preference divided by $7.50 (such price, the "Exchange Price" and such quotient, the "Exchange Rate").
Convertible Preferred Stock, Settlement Terms	SunOpta Foods may cause the Holders to exchange all of the Preferred Stock into a number of Common Shares based on the applicable Exchange Price if (i) fewer than 10% of the shares of 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 Exchange Price.
Preferred Stock, Voting Rights	In connection with the Subscription Agreement, the Company issued 11,333,333 Special Shares, Series 1 (the "Special Voting Shares") to the Investors, which entitle the Investors to one vote per Special Voting Share on all matters submitted to a vote of the holders of Common Shares, together as a single class, subject to certain exceptions. Additional Special Voting Shares will be issued, or existing Special Voting Shares will be redeemed, as necessary to ensure that the aggregate number of Special Voting Shares outstanding is equal to the number of shares of Preferred Stock outstanding from time to time multiplied by the Exchange Rate in effect at such time.
Preferred Stock, Participation Rights	For so long as the Investors beneficially own or control at least 50% of the Preferred Stock issued on October 7, 2016, including any corresponding Common Shares into which such Preferred Stock are exchanged, the Investors 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
Special Voting Shares, voting interest of the company	11.40%