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Bonus Programs - Summary of Number of Shares Held by the Trust (Detail)
$ in Millions
 12 Months Ended
Dec. 31, 2020
MXN ($)
Dec. 31, 2019
MXN ($)
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Fair value of shares held by trust $ 638 $ 488
FEMSA UBD [member]    
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Number of other equity instruments outstanding in share-based payment arrangement at beginning of period 2,249,665 2,278,460
Shares acquired by the administrative trust to employees 2,445,983 1,441,838
Shares released from administrative trust to employees upon vesting 1,280,748 1,470,633
Number of other equity instruments outstanding in share-based payment arrangement at end of period 3,414,900 2,249,665
KOFL UBL [member]    
Disclosure of terms and conditions of share-based payment arrangement [line items]    
Number of other equity instruments outstanding in share-based payment arrangement at beginning of period 752,847 697,226
Shares acquired by the administrative trust to employees 985,535 456,077
Shares released from administrative trust to employees upon vesting 378,224 400,456
Number of other equity instruments outstanding in share-based payment arrangement at end of period 1,360,158 752,847