Earnings (Loss) Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Numerator for basic earnings (loss) per share
Earnings (loss) attributable to SunOpta Inc.	$ 1,007	$ (9,055)	$ 4,368	$ 16,594
Less: dividends and accretion on Preferred Stock	(2,604)	(2,001)	(4,629)	(3,996)
Earnings (loss) attributable to common shareholders	$ (1,597)	$ (11,056)	$ (261)	$ 12,598
Denominator for basic earnings (loss) per share
Basic weighted-average number of shares outstanding	89,089	87,683	88,625	87,579
Basic earnings (loss) per share	$ (0.02)	$ (0.13)	$ (0.00)	$ 0.14
Numerator for diluted earnings (loss) per share
Earnings (loss) attributable to SunOpta Inc.	$ 1,007	$ (9,055)	$ 4,368	$ 16,594
Earnings (loss) attributable to common shareholders	$ (1,597)	$ (11,056)	$ (261)	$ 12,598
Denominator for diluted earnings (loss) per share
Basic weighted-average number of shares outstanding	89,089	87,683	88,625	87,579
Dilutive effect of the following:
Diluted weighted-average number of shares outstanding	89,089	87,683	88,625	87,743
Diluted earnings (loss) per share	$ (0.02)	$ (0.13)	$ (0.00)	$ 0.14
Stock Options And Restricted Stock Units [Member]
Dilutive effect of the following:
Dilutive Securities, Effect on Basic Earnings Per Share	0	0	0	164
Series A Preferred Stock [Member]
Numerator for basic earnings (loss) per share
Less: dividends and accretion on Preferred Stock	$ (2,066)	$ (2,001)	$ (4,091)	$ (3,996)
Numerator for diluted earnings (loss) per share
Less: dividends and accretion on Preferred Stock	$ (2,066)	$ (2,001)	$ (4,091)	$ (3,996)
Dilutive effect of the following:
Dilutive Securities, Effect on Basic Earnings Per Share	0	0	0	0
Series B Preferred Stock [Member]
Numerator for basic earnings (loss) per share
Less: dividends and accretion on Preferred Stock	$ (538)	$ 0	$ (538)	$ 0
Numerator for diluted earnings (loss) per share
Less: dividends and accretion on Preferred Stock	$ (538)	$ 0	$ (538)	$ 0
Dilutive effect of the following:
Dilutive Securities, Effect on Basic Earnings Per Share	0	0	0	0