Value Creation Plan (Narrative) (Details)	12 Months Ended
Dec. 29, 2018
Restructuring Cost And Reserve [Line Items]
Restructuring and related activities description	On October 7, 2016, the Company entered into a strategic partnership with Oaktree Capital Management L.P., a private equity investor (together with its affiliates, “Oaktree”), and, on that date, Oaktree invested $85.0 million through the purchase of cumulative, non-participating Series A Preferred Stock (the “Preferred Stock”) of the Company’s wholly-owned subsidiary, SunOpta Foods Inc. (“SunOpta Foods”) (see note ##Pref). Following the strategic partnership, with the assistance of Oaktree, the Company conducted a thorough review of its operations, management and governance, with the objective of maximizing the Company’s ability to deliver long-term value to its shareholders. As a product of this review, the Company implemented a Value Creation Plan built on four pillars: portfolio optimization, operational excellence, go-to-market effectiveness and process sustainability. The Company engaged third-party management consulting firms to support the design and implementation of the Value Creation Plan.
Restructuring and related cost caption that includes restructuring charges	For the year ended December 29, 2018, costs incurred included the remaining lease obligation related to the vacated nutrition bar processing facility (net of sublease rentals), and an additional impairment loss related to the Wahpeton roasting facility to reflect net proceeds of $0.7 million received on the sale of the facility. Net cash receipts also included proceeds on the sale of nutrition bar equipment of $0.7 million. The balance payable as at December 29, 2018, represents the remaining nutrition bar facility lease obligation (net of sublease rentals), which extends until December 2020. For the year ended December 30, 2017, costs incurred included an additional asset impairment loss of $3.7 million on the disposal of the San Bernardino assets, and facility closure costs of $0.6 million incurred by the Company for rent and maintenance of the San Bernardino facility prior to its disposal. In addition, includes asset impairment losses related to the exits from flexible resealable pouch and nutrition bar operations of $16.1 million, and consolidation of the Company’s roasted snack operations of $1.3 million. Cash payments in 2017 related to the early buy-outs of the San Bernardino and flexible resealable pouch equipment leases, net of proceeds on the disposal of those assets, as well as on the sale of the nutrition bar equipment. For the year ended December 31, 2016, represents asset impairment losses of $11.5 million related to the closures of the San Bernardino and Heuvelton facilities.

Value Creation Plan (Narrative) (Details)

12 Months Ended

Dec. 29, 2018

Restructuring Cost And Reserve [Line Items]

Restructuring and related activities description

On October 7, 2016, the Company entered into a strategic partnership with Oaktree Capital Management L.P., a private equity investor (together with its affiliates, “Oaktree”), and, on that date, Oaktree invested $85.0 million through the purchase of cumulative, non-participating Series A Preferred Stock (the “Preferred Stock”) of the Company’s wholly-owned subsidiary, SunOpta Foods Inc. (“SunOpta Foods”) (see note ##Pref). Following the strategic partnership, with the assistance of Oaktree, the Company conducted a thorough review of its operations, management and governance, with the objective of maximizing the Company’s ability to deliver long-term value to its shareholders. As a product of this review, the Company implemented a Value Creation Plan built on four pillars: portfolio optimization, operational excellence, go-to-market effectiveness and process sustainability. The Company engaged third-party management consulting firms to support the design and implementation of the Value Creation Plan.

Restructuring and related cost caption that includes restructuring charges

For the year ended December 29, 2018, costs incurred included the remaining lease obligation related to the vacated nutrition bar processing facility (net of sublease rentals), and an additional impairment loss related to the Wahpeton roasting facility to reflect net proceeds of $0.7 million received on the sale of the facility. Net cash receipts also included proceeds on the sale of nutrition bar equipment of $0.7 million. The balance payable as at December 29, 2018, represents the remaining nutrition bar facility lease obligation (net of sublease rentals), which extends until December 2020. For the year ended December 30, 2017, costs incurred included an additional asset impairment loss of $3.7 million on the disposal of the San Bernardino assets, and facility closure costs of $0.6 million incurred by the Company for rent and maintenance of the San Bernardino facility prior to its disposal. In addition, includes asset impairment losses related to the exits from flexible resealable pouch and nutrition bar operations of $16.1 million, and consolidation of the Company’s roasted snack operations of $1.3 million. Cash payments in 2017 related to the early buy-outs of the San Bernardino and flexible resealable pouch equipment leases, net of proceeds on the disposal of those assets, as well as on the sale of the nutrition bar equipment. For the year ended December 31, 2016, represents asset impairment losses of $11.5 million related to the closures of the San Bernardino and Heuvelton facilities.