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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
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
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 17.80% 15.90% 6.20%
Derivatives 1.00% 8.00% 0.50%
Employee benefits 2.20% 4.40% 1.70%
Other 2.60% 9.80% (0.10%)
Equity interest in net loss (income) of associated companies   (0.20%) 0.80%
Gain on derecognition of equity method investment     (6.40%)
Dividends received from associates (1.20%) (7.90%) (0.90%)
Foreign subsidiaries and other non-deductible items, net (8.30%) (10.80%) 2.00%
Effective tax rate 43.70% 48.60% 34.20%
Mexico [member]      
Impact of non-deductibleand non-taxable items:      
Effective tax rate 53.60% 68.10% 38.30%
Brazil [member]      
Impact of non-deductibleand non-taxable items:      
Use of tax credits in Brazil (0.40%) (0.60%) 0.40%