Description of business and significant accounting policies (Tables)

12 Months Ended

Dec. 30, 2017

Basis Of Presentation Fiscal Year End And New Accounting Pronouncements Disclosure [Abstract]

Property, Plant and Equipment Useful Life Schedule [Table Text Block]

Buildings	20 - 40 years
Machinery and equipment	5 - 20 years
Enterprise software	3 - 5 years
Office furniture and equipment	3 - 7 years
Vehicles	3 - 7 years

Intangible Assets Useful Life Schedule [Table Text Block]

Customer and other relationships	10 - 25 years
Patents and trademarks	15 years
Other	5 - 15 years