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Bonus Programs - Quantitative and qualitative objectives (Detail) - MXN ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2015
Disclosure of terms and conditions of share-based payment arrangement [line items]        
Percentage of bonus 50.00%      
Percentage of annual bonus 50.00%      
Vesting period 4 years     6 years
Compensation expense $ 575 $ 610 $ 401  
Top of range [member]        
Disclosure of terms and conditions of share-based payment arrangement [line items]        
Percentage of economic value added 70.00%      
Bottom of range [member]        
Disclosure of terms and conditions of share-based payment arrangement [line items]        
Percentage of economic value added 30.00%