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Financial Instruments - Summary of Net Effect of Changes in Fair Value of Derivative Financial Instruments that did not Meet Hedging Criteria for Accounting Purposes (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2017
MXN ($)
Dec. 31, 2017
USD ($)
Dec. 31, 2016
MXN ($)
Dec. 31, 2015
MXN ($)
Disclosure of net effect of changes in fair value of derivative financial instruments that did not meet hedging criteria for accounting purposes [Line Items]        
Market value gain (loss) on financial instruments $ 246 $ 13 $ 51 $ 142
Currency swap contract [member]        
Disclosure of net effect of changes in fair value of derivative financial instruments that did not meet hedging criteria for accounting purposes [Line Items]        
Market value gain (loss) on financial instruments (104)   (129) 105
Derivatives Not Designated For Hedge Accounting [Member] | Forward agreements to purchase foreign currency [member]        
Disclosure of net effect of changes in fair value of derivative financial instruments that did not meet hedging criteria for accounting purposes [Line Items]        
Market value gain (loss) on financial instruments 12   (56) 52
Derivatives Not Designated For Hedge Accounting [Member] | Currency swap contract [member]        
Disclosure of net effect of changes in fair value of derivative financial instruments that did not meet hedging criteria for accounting purposes [Line Items]        
Market value gain (loss) on financial instruments $ 337   $ 236 $ (20)