Income taxes (Components of continuing operations) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 29, 2018	Dec. 30, 2017	Dec. 31, 2016
Earnings (loss) from continuing operations before income taxes	$ (114,521)	$ (170,397)	$ (74,361)
US
Earnings (loss) from continuing operations before income taxes	(107,068)	(178,033)	(93,941)
CA
Earnings (loss) from continuing operations before income taxes	(13,408)	(3,286)	9,811
Europe And Other [Member]
Earnings (loss) from continuing operations before income taxes	$ 5,955	$ 10,922	$ 9,769

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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