Discontinued Operations (Operating results) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 01, 2017	Jul. 02, 2016	Jul. 01, 2017	Jul. 02, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on classification as held for sale	$ 0	$ 0	$ 0	$ 560
Recovery of income taxes during phase out	0	0	0	599
Earnings (loss) from discontinued operations, net of taxes				(834)
Loss from discontinued operations attributable to non-controlling interests	0	0	0	264
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc	0	$ 0	$ 0	(570)
Opta Minerals Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues from discontinued operations	0			24,896
Costs of Goods Sold	0			(22,133)
Selling, general and administrative expenses	0			(3,024)
Other Income (Expense), net	0			(794)
Foreign exchange gain (loss)	0			(454)
Interest Expense	0			(484)
Earning (loss) before income tax	0			(1,993)
Gain on classification as held for sale	0			560
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax	0			(1,433)
Recovery of income taxes during phase out	0			599
Earnings (loss) from discontinued operations, net of taxes				(834)
Loss from discontinued operations attributable to non-controlling interests	0			264
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc	$ 0			$ (570)