Employee benefits, Significant actuarial assumptions (Details) $ in Thousands	Dec. 31, 2020 MXN ($) Employee	Dec. 31, 2019 Employee
Significant actuarial assumptions [Abstract]
Percentage of employees working under collective bargaining agreements	12.00%	18.00%
Number of employees \| Employee	934	1,099
Discount Rate [Member]
Significant actuarial assumptions [Abstract]
Significant actuarial assumptions used for valuation	7.50%	8.50%
Discount Rate [Member] \| 1.0% Increase [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (54)
Discount Rate [Member] \| 1.0% Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ 6,598
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	$ 5,711
Salary Increase Rate [Member] \| 1.0% Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (678)
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	16.10%	18.30%
Average Working Life Expectancy [Member] \| One year Increase [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ 3,426
Average Working Life Expectancy [Member] \| One year Decrease [Member]
Significant actuarial assumptions [Abstract]
Increase (decrease) in defined benefit obligation	$ (3,490)

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
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-IssueDate 2020-01-01
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- References

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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
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-IssueDate 2020-01-01
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