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Accounts Receivable - Summary of Changes in Allowance for Doubtful Accounts (Detail) - MXN ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Allowance For Doubtful Accounts [Abstract]      
Balance at beginning of the year $ 451 $ 283 $ 367
Allowance for the year 40 6 52
Charges and write-offs of uncollectible accounts (62) (3) (62)
Added in business combinations 86 94  
Effects of changes in foreign exchange rates (45) 71 (74)
Effect Venezuela (2)    
Balance at end of the year $ 468 $ 451 $ 283