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Pensions and Post-Employment Benefits - Summary of Significant Assumptions Used in the Determination of the Benefit Obligation (Detail) - Defined Benefit Obligation [Member]
Dec. 31, 2018
Dec. 31, 2017
Mexico [member]    
Disclosure of defined benefit plans [line items]    
Discount rates 10.80% 9.30%
Rate of return on plan assets 10.80% 9.30%
Rate of salary increases 4.00% 4.00%
United States [member]    
Disclosure of defined benefit plans [line items]    
Discount rates 4.50% 3.90%
Rate of return on plan assets 4.50% 3.90%
Rate of salary increases 0.00% 0.00%
United Kingdom [member]    
Disclosure of defined benefit plans [line items]    
Discount rates 2.90% 2.40%
Rate of return on plan assets 2.90% 2.40%
Rate of salary increases 3.30% 3.20%
Top of range [member] | Other countries [member]    
Disclosure of defined benefit plans [line items]    
Discount rates 1.30% 1.30%
Rate of return on plan assets 1.30% 1.30%
Rate of salary increases 2.30% 1.50%
Bottom of range [member] | Other countries [member]    
Disclosure of defined benefit plans [line items]    
Discount rates 7.50% 6.30%
Rate of return on plan assets 7.50% 6.30%
Rate of salary increases 6.00% 6.00%