Bank indebtedness and Long-Term Debt (Narrative) (Details) $ in Thousands, € in Millions	12 Months Ended
	Dec. 30, 2017 USD ($)	Dec. 31, 2016 USD ($)	Jan. 02, 2016 USD ($)	Dec. 30, 2017 EUR (€)	Dec. 30, 2017 USD ($)
Debt Instrument [Line Items]
Repayment of Line of Credit Facilities	$ 0	$ 192,677	$ 0
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 30, 2017, the weighted-average interest rate on the facilities was 3.45%. On September 19, 2017 (the “Effective Date”), the Company entered into an amendment to the Global Credit Facility to add an additional U.S. asset-based credit subfacility of an aggregate principal amount of $15.0 million (the “New U.S. Subfacility”). The New U.S. Subfacility was fully drawn on the Effective Date. Amortization payments on the aggregate principal amount of the New U.S. Subfacility are equal to $2.5 million payable at the end of each fiscal quarter, commencing with the fiscal quarter ending March 31, 2019. Optional prepayment of borrowings under the New U.S. Subfacility are not permitted until the first anniversary of the Effective Date and are subject to certain availability conditions. Borrowings repaid under the New U.S. Subfacility may not be borrowed again. Borrowings under the New U.S. Subfacility bear interest at a margin over various reference rates. The applicable margin for the New U.S. Subfacility will be set quarterly based on average borrowing availability for the preceding fiscal quarter and will range 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. The initial margin for the New U.S. Subfacility is 2.50% with respect to base rate and prime rate borrowings and 3.50% with respect to eurocurrency rate borrowings. Obligations under the Global Credit Facility are guaranteed by substantially all of the Company’s subsidiaries and, subject to certain exceptions, such obligations are secured by first priority liens on substantially all of the assets of the Company. The Global Credit Facility contains a number of covenants that, among other things, restrict, subject to certain exceptions, the Company’s ability to create liens on assets; sell assets and enter into sale and leaseback transactions; pay dividends, prepay junior lien and unsecured indebtedness and make other restricted payments; incur additional indebtedness and make guarantees; make investments, loans or advances, including acquisitions; and engage in mergers or consolidations. The foregoing covenants are subject to certain threshold amounts and exceptions as set forth in the credit agreement.
Line of Credit Facility, Expiration Date	Feb. 10, 2021
Debt, Weighted Average Interest Rate				3.10%	3.10%
New US Subfacility [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Amendment Date	9/19/2017
Line of Credit Facility, Maximum Borrowing Capacity					$ 15,000
Line Of Credit Facility, Description	On September 19, 2017 (the “Effective Date”), the Company entered into an amendment to the Global Credit Facility to add an additional U.S. asset-based credit subfacility of an aggregate principal amount of $15.0 million (the “New U.S. Subfacility”). The New U.S. Subfacility was fully drawn on the Effective Date. Amortization payments on the aggregate principal amount of the New U.S. Subfacility are equal to $2.5 million payable at the end of each fiscal quarter, commencing with the fiscal quarter ending March 31, 2019. Optional prepayment of borrowings under the New U.S. Subfacility are not permitted until the first anniversary of the Effective Date and are subject to certain availability conditions. Borrowings repaid under the New U.S. Subfacility may not be borrowed again. Borrowings under the New U.S. Subfacility bear interest at a margin over various reference rates. The applicable margin for the New U.S. Subfacility will be set quarterly based on average borrowing availability for the preceding fiscal quarter and will range 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. The initial margin for the New U.S. Subfacility is 2.50% with respect to base rate and prime rate borrowings and 3.50% with respect to eurocurrency rate borrowings.
Line of Credit Facility, Date of First Required Payment	Mar. 31, 2019
Line Of Credit Facility Periodic Payment Principal	$ 2,500
Line Of Credit Facility Frequency Of Payments	Amortization payments on the aggregate principal amount of the New U.S. Subfacility are equal to $2.5 million payable at the end of each fiscal quarter, commencing with the fiscal quarter ending March 31, 2019.
Bulgarian credit facility [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Initiation Date	May 22, 2013
Line Of Credit Facility Amendment Date	6/28/2017
Line of Credit Facility, Maximum Borrowing Capacity | €				€ 4.5
Line Of Credit Facility, Description	On June 28, 2017, 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 April 30, 2018. As at December 30, 2017, the weighted-average interest rate on the Bulgarian credit facility was 2.75%.
Line of Credit Facility, Expiration Date	Apr. 30, 2018
Debt, Weighted Average Interest Rate				2.75%	2.75%
Senior Secured Second Lien Notes [Member]
Debt Instrument [Line Items]
Repayment of Line of Credit Facilities	$ 7,500
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”). The Company incurred $9.3 million of debt issuance costs related to the Notes, which were recorded as a reduction against the principal amount of the Notes and are being amortized over the six-year term of the Notes. Interest on the Notes is payable semi-annually in arrears on April 15 and October 15 at a rate of 9.5% per annum, commencing on April 15, 2017. The Notes will mature on October 9, 2022. Giving effect to the amortization of debt issuance costs, the effective interest rate on the Notes is approximately 10.4% per annum.
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, commencing on April 15, 2017.
Debt Instrument, Maturity Date	Oct. 09, 2022
Debt Instrument Redemption Description	Prior to October 9, 2018, SunOpta Foods may redeem some or all of the Notes at any time and from time to time at a “make-whole” redemption price set forth in the indenture governing the Notes. On or after October 9, 2018, SunOpta Foods may redeem the Notes, in whole or in part, at any time at the redemption prices 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. In addition, prior to October 9, 2018, SunOpta Foods may, on one or more occasions, redeem up to 35% of the aggregate principal amount of the Notes with the proceeds of certain equity offerings at a redemption price equal to 109.500% of the principal amount of the Notes redeemed, plus accrued and unpaid interest, if any, to but excluding the date of redemption. At any time prior to October 9, 2018, SunOpta Foods may also redeem, during each twelve-month period beginning on October 20, 2016, up to 10% of the aggregate principal amount of the Notes at a price equal to 103.000% of the aggregate principal amount of the Notes being redeemed, plus accrued and unpaid interest, if any, to but excluding the date of redemption. 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. On October 19, 2017, the Company repaid $7.5 million principal amount of the Notes at 103.000%. The premium paid and write-off of a pro-rata portion of debt issuance costs were charged to interest expense on the consolidated statement of operations.
Debt Instrument Interest Rate Effective Percentage				10.40%	10.40%
Debt Instrument Gross Issuance Expense					$ 9,300
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. The loan is secured by a first priority lien on equipment owned by TOC for a second processing line at its cocoa processing facility in the Netherlands.
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. The loan is fully guaranteed by TOC.
Debt Instrument, Maturity Date	Dec. 28, 2027
Debt Instrument Interest Rate Effective Percentage				3.06%	3.06%