Accounting policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule Of Property Plant And Equipment Useful Life [Table Text Block]

Rates are determined based on the estimated useful lives of the assets as follows:

Buildings	5 to 40 years
Plant and equipment	4 to 40 years
Distribution system	3 to 40 years
Office furniture, fixtures and equipment	3 to 10 years
Vehicles	3 to 10 years
Leasehold improvements	Shorter of 5 years or lease term
Lab equipment	5 to 10 years

Estimated Fair value Of Reporting Segment [Table Text Block]

The respective weightings the Company applied to each method as of December 31, 2017 were consistent with those used as of December 31, 2016 and were as follows:

Method	Retail			Bulk			Manufacturing
Discounted cash flow		80	%		80	%		80	%
Guideline public company		10	%		10	%		10	%
Mergers and acquisitions		10	%		10	%		10	%
		100	%		100	%		100	%