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Pensions and Post-Employment Benefits - Additional Information (Detail)
$ in Millions, $ in Millions
 12 Months Ended
Dec. 31, 2017
USD ($)
Dec. 31, 2017
MXN ($)
Dec. 31, 2016
MXN ($)
Dec. 31, 2015
USD ($)
Dec. 31, 2015
MXN ($)
Nov. 30, 2012
USD ($)
Disclosure of defined benefit plans [line items]            
Costs of defined contribution plans   $ 922 $ 865   $ 706  
Projected benefits obligation   56,346 52,219   43,840  
increase in the net projected liability   199 184   137  
Post employment healthcare benefits [member]            
Disclosure of defined benefit plans [line items]            
Projected benefits obligation   $ 1,080 837      
London Interbank Offered Rate (LIBOR) [Member]            
Disclosure of defined benefit plans [line items]            
Significant assumptions   0.50%        
Trinidad Cement Limited [member]            
Disclosure of defined benefit plans [line items]            
increase in the net projected liability $ 14 $ 271        
Mexico [member]            
Disclosure of defined benefit plans [line items]            
Projected benefits obligation   $ 3,213 $ 3,247      
Medical inflation rates used to determine the projected benefits obligation   7.00% 7.00%      
Puerto Rico [member]            
Disclosure of defined benefit plans [line items]            
Medical inflation rates used to determine the projected benefits obligation   6.90% 4.30%      
United Kingdom [member]            
Disclosure of defined benefit plans [line items]            
Projected benefits obligation   $ 35,602 $ 33,925      
Medical inflation rates used to determine the projected benefits obligation   6.70% 6.80%      
United States [member]            
Disclosure of defined benefit plans [line items]            
Projected benefits obligation   $ 6,378 $ 7,110      
Medical inflation rates used to determine the projected benefits obligation   5.00%        
Income from prior period adjustment of retirement benefit       $ 1 $ 13  
Spain [member]            
Disclosure of defined benefit plans [line items]            
Income from prior period adjustment of retirement benefit 5 $ 99        
CEMEX U.K. [member]            
Disclosure of defined benefit plans [line items]            
Operating assets           $ 553
Annual Rental Payment $ 20          
Percentage Of Annual Rate 5.00% 5.00%        
Secured assets Producing Annual Return period 25 years 25 years