Discontinued Operations (Opta Minerals Inc Narrative) (Details) $ in Thousands, CAD in Millions	3 Months Ended					6 Months Ended		12 Months Ended
	Jul. 02, 2016 CAD	Jul. 02, 2016 USD ($)	Apr. 02, 2016 CAD	Apr. 02, 2016 USD ($)	Jul. 04, 2015 USD ($)	Jul. 02, 2016 USD ($)	Jul. 04, 2015 USD ($)	Jan. 02, 2016 USD ($)	Apr. 02, 2016 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Earnings (loss) from discontinued operations, net of income taxes						$ (834)	$ (5,139)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc		$ 0			$ (2,747)	$ (570)	(3,467)
Opta Minerals Inc [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Group, Including Discontinued Operation, Description and Timing of Disposal						On February 11, 2016, Opta Minerals entered into a definitive acquisition agreement, pursuant to which Speyside agreed to acquire all of the issued and outstanding shares of Opta Minerals. The acquisition agreement was approved by Opta Minerals’ Boards of Directors, which recommended that Opta Minerals’ shareholders approve the transaction. Also on February 12, 2016, the Company entered into a support agreement pursuant to which it irrevocably agreed to vote all of its Opta Minerals’ shares in favor of the transaction.
Disposal Group, Including Discontinued Operation, Consideration			CAD 6.2						$ 4,800
Discontinued Operation Amount Of Cash Consideration On Sale			CAD 4.2	$ 3,200
Earnings (loss) from discontinued operations, net of income taxes		0			(4,058)	$ (834)	(5,139)	$ (10,500)
Income (Loss) from Discontinued Operations, Net of Tax, Attributable to SunOpta Inc		0			$ (2,747)	$ (570)	$ (3,467)	(7,700)
Fair Value of Assets Acquired								$ 4,500
Sale of business costs				800
Discontinued Operations, reduction in net proceeds on sale of business				500
Change in carry value of assets held for sale				1,100
Discontinued Operations Gain On Classification On Sale Of Business				$ 600
Opta Minerals Inc [Member] | Subordinated Promissory Note
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Discontinued Operation Amount of Subordinated Promissory Note on Sale	CAD 2.0	$ 1,500
Debt Instrument Interest Rate Stated Percentage	2.00%	2.00%				2.00%