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Income Taxes - Summary of Reconciliation of Statutory Income Tax Rate in Mexico to Consolidated Effective Income Tax Rate Recognized (Detail) | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Disclosure of temporary difference, unused tax losses and unused tax credits [line items] |  |  |
Statutory income tax rate in Mexico | 30.00% | 30.00% | 30.00%
Impact of non-deductibleand non-taxable items: |  |  |
Tax inflation effects | 7.30% | 17.80% | 15.90%
Derivatives | 0.40% | 1.00% | 8.00%
Employee benefits | 1.30% | 2.20% | 4.40%
Other | 6.30% | 2.60% | 9.80%
Equity interest in net loss of associated companies |  |  | (0.20%)
Dividends received from associates | (0.80%) | (1.20%) | (7.90%)
Foreign subsidiaries and other non-deductible items, net | 1.50% | (8.30%) | (10.80%)
Effective tax rate | 46.00% | 43.70% | 48.60%
Mexico [member] |  |  |
Impact of non-deductibleand non-taxable items: |  |  |
Effective tax rate | 45.30% | 53.60% | 68.10%
Brazil [member] |  |  |
Impact of non-deductibleand non-taxable items: |  |  |
Use of unrecognized tax credits in Brazil |  | (0.40%) | (0.60%)

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- Definition The applicable income tax rate. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2018-01-01 -Paragraph 81 -Subparagraph c -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition Tax rate effects, in aggregate, on the reconciliation between the average effective tax rate and the applicable tax rate that the entity does not separately disclose in the reconciliation. [Refer: Average effective tax rate; Applicable tax rate] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 12 -IssueDate 2018-01-01 -Paragraph 81 -Subparagraph c -Clause ii -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=12&date=2018-03-01&anchor=para_81_c_ii&doctype=Standard -URIDate 2018-03-16 + Details
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