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Income Taxes - Summary of Tax Losses Carryforwards and their Years of Expiration (Detail)
$ in Millions
Dec. 31, 2020
MXN ($)
Major components of tax expense (income) [abstract]  
2024 $ 63
2025 734
2026 1,831
2027 0
2028 2,222
2029 3,136
2030 and thereafter 1,071
No expiration (Brazil) 12,465
Tax loss carryforwards $ 21,522