Discontinued Operations (Opta Minerals Operating Results) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016		Jan. 02, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Earning (loss) before income tax	$ 0	$ (1,993)		$ (17,377)
Gain (loss) on classification as held for sale	0	560		(10,515)
Recovery of (provision for) income taxes during phase out	0	599		(402)
Earnings (loss) from discontinued operations, net of taxes		(834)		(28,294)
Loss from discontinued operations attributable to non-controlling interests	0	264		8,819
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc	$ 0	(570)		(19,475)
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		113,805
Costs of Goods Sold		(22,133)		(99,256)
Selling, general and administrative expenses		(3,024)		(11,170)
Intangible Asset Amortization		0		(1,987)
Other Expense, net		(794)	[1]	(15,097)
Foreign exchange gain (loss)		(454)		717
Interest Expense		(484)		(4,389)
Earning (loss) before income tax		(1,993)		(17,377)
Gain (loss) on classification as held for sale		560		(10,515)
Pre-tax gain on sale - earnings		(1,433)		(27,892)
Recovery of (provision for) income taxes during phase out		599		(402)
Earnings (loss) from discontinued operations, net of taxes		(834)		(28,294)
Loss from discontinued operations attributable to non-controlling interests		264		8,819
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc		$ (570)		$ (19,475)

[1] (1) For the years ended December 31, 2016 and January 2, 2016, other expense, net includes charges related to the impairment of long-lived assets of Opta Minerals of $0.4 million and $12.4 million, respectively.