Earnings per share (Table) (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Jan. 02, 2016
Earnings Per Share Abstract
Income (Loss) from Continuing Operations Attributable to Parent	$ (135,320)	$ (50,618)	$ (2,996)
dividends and accretion on Series A Preferred Stock	(7,809)	(1,812)	0
Earning (loss) from continuing operations available to common shareholders	(143,129)	(52,430)	(2,996)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc	0	(570)	(19,475)
Earnings (loss) available to common shareholders	$ (143,129)	$ (53,000)	$ (22,471)
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Weighted Average Number of Shares Outstanding, Basic	86,355,000	85,569,000	72,408,000
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	0	0	0
Weighted Average Number of Shares Outstanding, Diluted	86,355,000	85,569,000	72,408,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	2,540,189	2,321,448	856,492
Earnings (loss) per share - basic
from continuing operations basic	$ (1.66)	$ (0.61)	$ (0.04)
from discontinued operations basic	0	(0.01)	(0.27)
Earnings Per Share Total	(1.66)	(0.62)	(0.31)
Earnings (loss) per share - diluted
from continuing operations diluted	(1.66)	(0.61)	(0.04)
from discontinued operations diluted	0	(0.01)	(0.27)
Earnings Per Share Diluted Total	$ (1.66)	$ (0.62)	$ (0.31)
Options Held [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	0	0	0
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	815,952	66,166	54,316
Warrant [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	0	0	0
Series A Preferred Stock [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Dilutive Securities, Effect on Basic Earnings Per Share, Including Options and Restrictive Stock Units	0
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	11,333,333	2,670,320