Income taxes (Unrecognized tax benefits) (Details) - USD ($) $ in Thousands	12 Months Ended
Jan. 02, 2016	Jan. 03, 2015
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits	$ 2,575	$ 2,910
Unrecognized Tax Benefits Decreases Resulting From Prior Period Tax Positions	(855)	(553)
Unrecognized Tax Benefits Increases Resulting From Current Period Tax Positions	0	218
Unrecognized Tax Benefits	$ 1,720	$ 2,575

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- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 15A
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Unrecognized Tax Benefit
-URI http://asc.fasb.org/extlink&oid=6527854

+ Details

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

+ References

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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