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Income Taxes - Summary of Income Tax Rate (Detail)
 12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Income Tax Disclosure [Abstract]    
Canadian statutory income tax rate 26.50% 26.50%
Manufacturing and processing profits deduction (0.30%) (0.30%)
Foreign rate differentials (0.40%) (0.20%)
Losses not benefited 1.60% 0.80%
Utilization of losses previously not benefited (0.10%) (0.20%)
Earnings of equity accounted investees (1.40%) (1.20%)
Tax on repatriation of foreign earnings 1.40% 0.70%
Valuation allowance on deferred tax assets (0.10%) (0.40%)
US tax reform (0.80%)  
Research and development tax credits (1.20%) (1.50%)
Reserve for uncertain tax positions (0.20%) 0.20%
Non-deductible foreign exchange losses 0.30% 1.30%
Others (0.50%) (0.30%)
Effective income tax rate 24.80% 25.40%