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Post-Employment and Other Long-Term Employees Benefits - Additional Information (Detail) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]      
Expected amortization of actuarial losses in year 2018 $ 9    
Pension plans with accumulated benefit obligations in excess of plan assets, accumulated benefit obligation 853 $ 738  
Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets 511 443  
Accrued benefits related to defined contribution pension plans 19 16  
Annual cost of defined contribution plans 74 70 $ 70
Pension Benefits [Member]      
Defined Benefit Plan Disclosure [Line Items]      
Pension plans with benefit obligations in excess of plan assets, benefit obligation 961 811  
Pension plans with benefit obligations in excess of plan assets, fair value of plan assets 511 464  
Employer contributions 27 $ 27  
Expected contribution in cash $ 26