Summary of significant accounting policies (Tables)

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule Of Composite Depreciation Rate [Table Text Block]

Depreciation of property, plant and equipment is provided using the straight-line method over their estimated useful lives:

Buildings	20-40 years
Furniture, fixtures and office equipment	5 years
Leasehold improvement	Shorter of the remaining lease terms or estimated useful lives
Machinery and equipment	10 years
Motor vehicles	5 years