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Other Post-Employment Benefits and Other Employee Benefit Plans - Additional Information (Detail)
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Other Post-Employment Benefits and Other Employee Benefit Plans [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Minimum age of employee for entitlement of other post retirement benefit plans 55 years  
Minimum number of years of service for entitlement of other post retirement benefit plans 10 years  
Amortization period of transition obligation 20 years  
Accumulated post-retirement benefit obligations, weighted-average discount rate 3.90% 4.00%
Belgian Plans [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Health care cost trend rate assumed for the year 4.00%  
U.S. Plans [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Health care cost trend rate assumed for the year 7.00%  
Health care cost trend rate downgraded 5.00%  
Year in which rate reaches ultimate trend rate 2022  
Canada Plans [Member]    
Defined Benefit Plan Disclosure [Line Items]    
Health care cost trend rate assumed for the year 5.50%  
Health care cost trend rate downgraded 5.00%  
Year in which rate reaches ultimate trend rate 2018