Employee benefits, Significant actuarial assumptions (Details) - Domestic Defined Benefit Plans [Member] $ in Thousands	Dec. 31, 2017 MXN ($) Employee	Dec. 31, 2016 Employee
Significant actuarial assumptions [Abstract]
Percentage of employees working under collective bargaining agreements	17.00%	25.00%
Number of employees \| Employee	1,494	1,499
Discount Rate [Member]
Significant actuarial assumptions [Abstract]
Significant actuarial assumptions used for valuation	9.25%	9.00%
Discount Rate [Member] \| 1.0% Increase [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (6,161)
Discount Rate [Member] \| 1.0% Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ 6,565
Salary Increase Rate [Member]
Significant actuarial assumptions [Abstract]
Significant actuarial assumptions used for valuation	4.00%	4.00%
Salary Increase Rate [Member] \| 1.0% Increase [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ 4,416
Salary Increase Rate [Member] \| 1.0% Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (4,173)
Inflation Rate [Member]
Significant actuarial assumptions [Abstract]
Significant actuarial assumptions used for valuation	3.50%	3.50%
Average Working Life Expectancy [Member]
Significant actuarial assumptions [Abstract]
Significant actuarial assumptions used for valuation	19.80%	19.80%
Average Working Life Expectancy [Member] \| One year Increase [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ 5,583
Average Working Life Expectancy [Member] \| One year Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (5,736)

The increase (decrease) in a defined benefit obligation that would have been caused by an increase or decrease in a significant actuarial assumption that was reasonably possible at the end of the reporting period.

No definition available.

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- Definition

Refers to the percentage of the entity's employees that are under collective bargaining agreements that are subject to annual salary reviews and biannually for other compensation.

+ References

No definition available.

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- Definition

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [member]]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 19
-IssueDate 2017-01-01
-Paragraph 144
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=19&date=2017-03-01&anchor=para_144&doctype=Standard
-URIDate 2017-03-09

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- References

No definition available.

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- Definition

The number of personnel employed by the entity at a date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
-Number 1
-IssueDate 2017-01-01
-Paragraph 112
-Subparagraph c
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2017-03-01&anchor=para_112_c&doctype=Standard
-URIDate 2017-03-09

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- Details

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