Discontinued Operations (Opta Minerals Operating Results) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Earning (loss) before income tax	$ 0	$ 0	$ (570)
Gain (loss) on classification as held for sale	0	0	560
Recovery of (provision for) income taxes during phase out	0	0	599
Earnings (loss) from discontinued operations, net of taxes			(834)
Loss from discontinued operations attributable to non-controlling interests	0	0	264
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc	$ 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			24,896
Costs of Goods Sold			(22,133)
Selling, general and administrative expenses			(3,024)
Other Expense, net			(1,248)
Interest Expense			(484)
Earning (loss) before income tax			(1,993)
Gain (loss) on classification as held for sale			560
Pre-tax gain on sale - earnings			(1,433)
Recovery of (provision for) income taxes during phase out			599
Earnings (loss) from discontinued operations, net of taxes			(834)
Loss from discontinued operations attributable to non-controlling interests			264
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc			$ (570)