Bank indebtedness and Long-Term Debt (Narrative) (Details) $ in Thousands, € in Millions	12 Months Ended
	Dec. 29, 2018 USD ($)	Dec. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 29, 2018 EUR (€)	Dec. 29, 2018 USD ($)
Debt Instrument [Line Items]
Repayment of Line of Credit Facilities	$ 0	$ 0	$ 192,677
Global Credit Facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Initiation Date	Feb. 11, 2016
Line of Credit Facility, Maximum Borrowing Capacity					$ 350,000
Line Of Credit Facility Increase Decrease In Maximum Borrowing Capacity	$ 100,000
Line Of Credit Facility, Description	On February 11, 2016, the Company entered into a five-year credit agreement for a senior secured asset-based revolving credit facility with a syndicate of banks in the maximum aggregate principal amount of $350.0 million, subject to borrowing base capacity (the “Global Credit Facility”). The Global Credit Facility is used to support the working capital and general corporate needs of the Company’s global operations, in addition to funding future strategic initiatives. The Global Credit Facility also includes borrowing capacity available for letters of credit and provides for borrowings on same-day notice, including in the form of swingline loans. Subject to customary borrowing conditions and the agreement of any such lenders to provide such increased commitments, the Company may request to increase the total lending commitments under the Global Credit Facility to a maximum aggregate principal amount not to exceed $450.0 million. Outstanding principal amounts under the Global Credit Facility are repayable in full on the maturity date of February 10, 2021. Individual borrowings under the Global Credit Facility have terms of six months or less and bear interest based on various reference rates, including prime rate and LIBOR plus an applicable margin. The applicable margin in the Global Credit Facility ranges from 1.25% to 1.75% for loans bearing interest based on LIBOR and from 0.25% to 0.75% for loans bearing interest based on the prime rate and, in each case, is set quarterly based on average borrowing availability for the preceding fiscal quarter. As at December 29, 2018, the weighted-average interest rate on the facilities was 4.48%.
Line of Credit Facility, Expiration Date	Feb. 10, 2021
Debt, Weighted Average Interest Rate				4.48%	4.48%
US Subfacility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity					$ 20,000
Line Of Credit Facility, Description	On September 19, 2017, the Company entered into an amendment to the Global Credit Facility to add a $15.0 million U.S. asset-based credit subfacility (the “U.S. Subfacility”). On October 22, 2018, the Global Credit Facility was further amended to increase the commitment under the U.S. Subfacility by $5.0 million. The entire $20.0 million available for borrowing under the U.S. Subfacility was fully drawn as of October 22, 2018.
Line of Credit Facility, Date of First Required Payment	Mar. 31, 2019
Line Of Credit Facility Periodic Payment Principal	$ 3,300
Line Of Credit Facility Frequency Of Payments	Commencing with the fiscal quarter ending March 31, 2019, amortization payments on the aggregate principal amount of the U.S. Subfacility are equal to $3.33 million, which payments may be funded through borrowings under the revolving facilities of the Global Credit Facility.
Line Of Credit Facility Interest Rate Description	Borrowings repaid under the U.S. Subfacility may not be borrowed again. Borrowings under the U.S. Subfacility bear interest at a margin over various reference rates. The applicable margin for the U.S. Subfacility is set quarterly based on average borrowing availability for the preceding fiscal quarter ranges from 2.00% to 2.50% with respect to base rate and prime rate borrowings and from 3.00% to 3.50% for eurocurrency rate and bankers’ acceptance rate borrowings. As at December 29, 2018, the applicable margin was 3.50%.
Bulgarian credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Initiation Date	May 22, 2013
Line of Credit Facility, Maximum Borrowing Capacity | €				€ 4.5
Line Of Credit Facility, Description	On July 27, 2018, a subsidiary of The Organic Corporation B.V. (“TOC”), a wholly-owned subsidiary of the Company, extended its revolving credit facility agreement dated May 22, 2013, to provide up to €4.5 million to cover the working capital needs of TOC’s Bulgarian operations. The facility is secured by the accounts receivable and inventories of the Bulgarian operations and is fully guaranteed by TOC. Interest accrues under the facility based on EURIBOR plus a margin of 2.75%, and borrowings under the facility are repayable in full on May 31, 2019. As at December 29, 2018, the weighted-average interest rate on the Bulgarian credit facility was 2.75%.
Line of Credit Facility, Expiration Date	May 31, 2019
Debt, Weighted Average Interest Rate				2.75%	2.75%
Senior Secured Second Lien Notes [Member]
Debt Instrument [Line Items]
Debt Instrument Description	On October 20, 2016, SunOpta Foods issued $231.0 million of 9.5% Senior Secured Second Lien Notes due 2022 (the “Notes”). As at December 29, 2018, the outstanding principal amount of the Notes was $223.5 million, reflecting the redemption of $7.5 million principal amount by SunOpta Foods in October 2017. Debt issuance costs are recorded as a reduction against the principal amount of the Notes and are being amortized over the six-year term of the Notes.
Debt Instrument, Issuance Date	Oct. 20, 2016
Debt Instrument, Face Amount					$ 231,000
Debt Instrument, Frequency of Periodic Payment	Interest on the Notes is payable semi-annually in arrears on April 15 and October 15 at a rate of 9.5% per annum.
Debt Instrument, Maturity Date	Oct. 09, 2022
Debt Instrument Redemption Description	At any time after October 9, 2018, SunOpta Foods may redeem the Notes, in whole or in part, at a redemption price equal to 107.125% through October 8, 2019, 104.750% from October 9, 2019 through October 8, 2020, 102.375% from October 9, 2020 through October 8, 2021 and at par thereafter, plus accrued and unpaid interest, if any, to but excluding the date of redemption. Certain additional redemption rights were applicable prior to October 9, 2018. In the event of a change of control, SunOpta Foods will be required to make an offer to repurchase the Notes at 101.000% of their principal amount, plus accrued and unpaid interest, if any, to the date of purchase. The Notes are secured by second-priority liens on substantially all of the assets that secure the credit facilities provided under the Global Credit Facility, subject to certain exceptions and permitted liens. The Notes are senior secured obligations and rank equally in right of payment with SunOpta Foods’ existing and future senior debt and senior in right of payment to any future subordinated debt. The Notes are effectively subordinated to debt under the Global Credit Facility and any future indebtedness secured on a first priority basis. The Notes are initially guaranteed on a senior secured second-priority basis by the Company and each of its subsidiaries (other than SunOpta Foods) that guarantees indebtedness under the Global Credit Facility, subject to certain exceptions. The Notes are subject to covenants that, among other things, limit the Company’s ability to (i) incur additional debt or issue preferred stock; (ii) pay dividends and make certain types of investments and other restricted payments; (iii) create liens; (iv) enter into transactions with affiliates; (v) sell assets; and (vi) create restrictions on the ability of restricted subsidiaries to pay dividends, make loans or advances or transfer assets to the Company, SunOpta Foods or any guarantor of the Notes. The foregoing covenants are subject to certain threshold amounts and exceptions as set forth in the indenture governing the Notes. In addition, the indenture provides for customary events of default (subject in certain cases to customary grace and cure periods), which include nonpayment, breach of covenants in the indenture, certain payment defaults or acceleration of other indebtedness, a failure to pay certain judgments and certain events of bankruptcy and insolvency. If an event of default occurs and is continuing, the trustee or holders of at least 25% in principal amount of the outstanding Notes may declare the principal of and accrued and unpaid interest on, if any, all the Notes to be due and payable. As at December 29, 2018, the estimated fair value of the outstanding Notes was approximately $240 million, based on quoted prices of the most recent over-the-counter transactions (Level 2).
Debt Instrument Interest Rate Effective Percentage				10.40%	10.40%
Asset-Backed Term Loan [Member]
Debt Instrument [Line Items]
Debt Instrument Description	On December 28, 2017, TOC entered into a €3.0 million asset-backed term loan.
Debt Instrument, Issuance Date	Dec. 28, 2017
Debt Instrument, Face Amount | €				€ 3.0
Debt Instrument, Frequency of Periodic Payment	Interest on this loan accrues at an effective rate of 3.06% and the loan matures on December 28, 2027. Principal and accrued interest is repayable in equal monthly installments.
Debt Instrument, Maturity Date	Dec. 28, 2027
Debt Instrument Interest Rate Effective Percentage				3.06%	3.06%
Asset-Backed Term Loan2 [Member]
Debt Instrument [Line Items]
Debt Instrument Description	On January 8, 2019, TOC entered into a second asset-backed term loan for €1.6 million
Debt Instrument, Issuance Date	Jan. 08, 2019
Debt Instrument, Face Amount | €				€ 1.6
Debt Instrument, Frequency of Periodic Payment	accrues interest at an effective rate of 3.42% and matures on December 28, 2027. Principal and accrued interest on these loans are repayable in equal monthly installments.
Debt Instrument, Maturity Date	Dec. 28, 2027
Debt Instrument Interest Rate Effective Percentage				3.42%	3.42%