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Financial Instruments - Sensitivity Analysis of Interest Rate Risks (Detail) - Interest rate risk [member] - MXN ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Interest rate swaps [member] | FEMSA Entity Excluding Coca-Cola FEMSA [Member]      
Disclosure of Interest Rate Risk Exposure [line items]      
Effect on Equity $ (354) $ (432) $ (359)
Change in interest rate (1.00%) (1.00%) (1.00%)
Interest rate swaps [member] | Coca-Cola FEMSA [member]      
Disclosure of Interest Rate Risk Exposure [line items]      
Effect on Equity   $ (37) $ (1,976)
Change in interest rate   (1.00%) (1.00%)
Unhedged Portion Bank Loans [member]      
Disclosure of Interest Rate Risk Exposure [line items]      
Change in interest rate 1.00% 1.00% 1.00%
Effect on profit loss $ (110) $ (50) $ (145)