Description of Business and Significant Accounting Policies	9 Months Ended
Sep. 29, 2018
Basis Of Presentation Fiscal Year End And New Accounting Pronouncements Disclosure [Abstract]
Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block]	1. Description of Business and Significant Accounting Policies SunOpta Inc. (the “Company” or “SunOpta”) was incorporated under the laws of Canada on November 13, 1973. The Company operates businesses focused on a healthy products portfolio that promotes sustainable well-being. The Company’s two reportable segments, Global Ingredients and Consumer Products, operate in the natural, organic and specialty food sectors and utilize an integrated business model to bring cost-effective and quality products to market. Basis of Presentation The interim consolidated financial statements of the Company have been prepared in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X promulgated under the Securities Exchange Act of 1934, as amended, and in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information. Accordingly, these condensed interim consolidated financial statements do not include all of the disclosures required by U.S. GAAP for annual financial statements. In the opinion of management, all adjustments considered necessary for fair presentation have been included and all such adjustments are of a normal, recurring nature. Operating results for the quarter and three quarters ended September 29, 2018 are not necessarily indicative of the results that may be expected for the full fiscal year ending December 29, 2018 or for any other period. The interim consolidated financial statements include the accounts of the Company and its subsidiaries, and have been prepared on a basis consistent with the annual consolidated financial statements for the year ended December 30, 2017, except as described below under “Recent Accounting Pronouncements – Adoption of New Accounting Standards”. For further information, refer to the consolidated financial statements, and notes thereto, included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 30, 2017. Fiscal Year The fiscal year of the Company consists of a 52- or 53-week period ending on the Saturday closest to December 31. Fiscal year 2018 is a 52-week period ending on December 29, 2018, with quarterly periods ending on March 31, June 30 and September 29, 2018. Fiscal year 2017 was a 52-week period ending on December 30, 2017, with quarterly periods ending on April 1, July 1 and September 30, 2017. Recent Accounting Pronouncements Adoption of New Accounting Standard As at December 31, 2017 (the first day of fiscal 2018), the Company adopted Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASC Topic 606”), which superseded all previous revenue recognition guidance under U.S. GAAP. Under this new standard, a company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services. The Company analyzed its significant customer contracts to determine the effects of ASC Topic 606. In particular, the Company assessed under the new guidance whether its contracts with customers to produce certain consumer-packaged goods would require the Company to recognize revenue over time versus at a point in time, based on whether the given product has an alternative use and whether there is an enforceable right to payment under the contract for product produced to date. Based on its assessment, the Company concluded that it does not satisfy the criteria to recognize revenue over time. Accordingly, the Company continues to recognize revenue at a point in time consistent with its previous policies and processes, which is typically when title and physical possession of the product has transferred to the customer. The Company also transacts with certain customers on a bill-and-hold basis, whereby the Company bills a customer for product to be delivered at a later date. Prior to the adoption of ASC Topic 606, the Company deferred the recognition of revenue related to these bill-and-hold arrangements, as the arrangements did not typically include a fixed delivery schedule. As this criterion is no longer a consideration under ASC Topic 606, these arrangements now qualify for revenue recognition at the point in time that the customer obtains control of the goods. With the exception of bill-and-hold arrangements, the adoption of ASC Topic 606 did not have a significant impact on the Company’s consolidated financial statements and revenue recognition practices, or its internal controls. The Company adopted ASC Topic 606 using the modified retrospective approach, which resulted in a cumulative-effect adjustment of $0.3 million to opening accumulated deficit as at December 31, 2017, related to the recognition of $4.8 million of bill-and-hold revenue deferred under previous U.S. GAAP. The change in the timing of the recognition of bill-and-hold revenue did not have a material impact on the Company’s consolidated statement of operations for the quarter and three quarters ended September 29, 2018 or consolidated balance sheet as at September 29, 2018. See note 2 for additional disclosures under ASC Topic 606. Recently Issued Accounting Standards, Not Adopted as at September 29, 2018 In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, “Measurement of Credit Losses on Financial Instruments”, which requires measurement and recognition of expected versus incurred credit losses for most financial assets. ASU 2016-13 is effective for interim and annual periods beginning after December 15, 2019. The Company is currently assessing the impact that this standard will have on its consolidated financial statements. In February 2016, the FASB issued ASU 2016-02, “Leases”, a comprehensive new standard that amends various aspects of legacy accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability for leases with a duration of greater than one year. The guidance is effective on a modified retrospective basis for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU 2018-11 to provide a transition option for entities to apply the new guidance at the adoption date by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption rather than in the earliest period presented in the financial statements. Under this transition option, entities will continue to apply the legacy accounting guidance for leases, including disclosure requirements, in the comparative periods presented in the year they adopt the new leases standard. The Company will adopt ASU 2016-02, as amended, as at December 30, 2018 (the first day of fiscal 2019) and intends to elect the transition option provided under ASU 2018-11. With the assistance of a third party, the Company is in the process of compiling the required information from its significant operating lease contracts to determine the opening balances of the right-to-use assets and corresponding lease liabilities.

Description of Business and Significant Accounting Policies

9 Months Ended

Sep. 29, 2018

Basis Of Presentation Fiscal Year End And New Accounting Pronouncements Disclosure [Abstract]

Organization Consolidation And Presentation Of Financial Statements Disclosure [Text Block]

1. Description of Business and Significant Accounting Policies

SunOpta Inc. (the “Company” or “SunOpta”) was incorporated under the laws of Canada on November 13, 1973. The Company operates businesses focused on a healthy products portfolio that promotes sustainable well-being. The Company’s two reportable segments, Global Ingredients and Consumer Products, operate in the natural, organic and specialty food sectors and utilize an integrated business model to bring cost-effective and quality products to market.

Basis of Presentation

The interim consolidated financial statements of the Company have been prepared in accordance with the instructions to Form 10-Q and Rule 10-01 of Regulation S-X promulgated under the Securities Exchange Act of 1934, as amended, and in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information. Accordingly, these condensed interim consolidated financial statements do not include all of the disclosures required by U.S. GAAP for annual financial statements. In the opinion of management, all adjustments considered necessary for fair presentation have been included and all such adjustments are of a normal, recurring nature. Operating results for the quarter and three quarters ended September 29, 2018 are not necessarily indicative of the results that may be expected for the full fiscal year ending December 29, 2018 or for any other period. The interim consolidated financial statements include the accounts of the Company and its subsidiaries, and have been prepared on a basis consistent with the annual consolidated financial statements for the year ended December 30, 2017, except as described below under “Recent Accounting Pronouncements – Adoption of New Accounting Standards”. For further information, refer to the consolidated financial statements, and notes thereto, included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 30, 2017.

Fiscal Year

The fiscal year of the Company consists of a 52- or 53-week period ending on the Saturday closest to December 31. Fiscal year 2018 is a 52-week period ending on December 29, 2018, with quarterly periods ending on March 31, June 30 and September 29, 2018. Fiscal year 2017 was a 52-week period ending on December 30, 2017, with quarterly periods ending on April 1, July 1 and September 30, 2017.

Recent Accounting Pronouncements

Adoption of New Accounting Standard

As at December 31, 2017 (the first day of fiscal 2018), the Company adopted Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606)” (“ASC Topic 606”), which superseded all previous revenue recognition guidance under U.S. GAAP. Under this new standard, a company recognizes revenue when it transfers promised goods or services to customers in an amount that reflects the consideration to which the company expects to be entitled in exchange for those goods or services.

The Company analyzed its significant customer contracts to determine the effects of ASC Topic 606. In particular, the Company assessed under the new guidance whether its contracts with customers to produce certain consumer-packaged goods would require the Company to recognize revenue over time versus at a point in time, based on whether the given product has an alternative use and whether there is an enforceable right to payment under the contract for product produced to date. Based on its assessment, the Company concluded that it does not satisfy the criteria to recognize revenue over time. Accordingly, the Company continues to recognize revenue at a point in time consistent with its previous policies and processes, which is typically when title and physical possession of the product has transferred to the customer. The Company also transacts with certain customers on a bill-and-hold basis, whereby the Company bills a customer for product to be delivered at a later date. Prior to the adoption of ASC Topic 606, the Company deferred the recognition of revenue related to these bill-and-hold arrangements, as the arrangements did not typically include a fixed delivery schedule. As this criterion is no longer a consideration under ASC Topic 606, these arrangements now qualify for revenue recognition at the point in time that the customer obtains control of the goods. With the exception of bill-and-hold arrangements, the adoption of ASC Topic 606 did not have a significant impact on the Company’s consolidated financial statements and revenue recognition practices, or its internal controls.

The Company adopted ASC Topic 606 using the modified retrospective approach, which resulted in a cumulative-effect adjustment of $0.3 million to opening accumulated deficit as at December 31, 2017, related to the recognition of $4.8 million of bill-and-hold revenue deferred under previous U.S. GAAP. The change in the timing of the recognition of bill-and-hold revenue did not have a material impact on the Company’s consolidated statement of operations for the quarter and three quarters ended September 29, 2018 or consolidated balance sheet as at September 29, 2018.

See note 2 for additional disclosures under ASC Topic 606.

Recently Issued Accounting Standards, Not Adopted as at September 29, 2018

In June 2016, the Financial Accounting Standards Board (“FASB”) issued ASU 2016-13, “Measurement of Credit Losses on Financial Instruments”, which requires measurement and recognition of expected versus incurred credit losses for most financial assets. ASU 2016-13 is effective for interim and annual periods beginning after December 15, 2019. The Company is currently assessing the impact that this standard will have on its consolidated financial statements.

In February 2016, the FASB issued ASU 2016-02, “Leases”, a comprehensive new standard that amends various aspects of legacy accounting guidance for leases, including the recognition of a right-of-use asset and a lease liability for leases with a duration of greater than one year. The guidance is effective on a modified retrospective basis for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. In July 2018, the FASB issued ASU 2018-11 to provide a transition option for entities to apply the new guidance at the adoption date by recognizing a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption rather than in the earliest period presented in the financial statements. Under this transition option, entities will continue to apply the legacy accounting guidance for leases, including disclosure requirements, in the comparative periods presented in the year they adopt the new leases standard. The Company will adopt ASU 2016-02, as amended, as at December 30, 2018 (the first day of fiscal 2019) and intends to elect the transition option provided under ASU 2018-11. With the assistance of a third party, the Company is in the process of compiling the required information from its significant operating lease contracts to determine the opening balances of the right-to-use assets and corresponding lease liabilities.