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Financial Instruments and Financial Risk Management - Additional Information (Detail)
$ in Millions, $ in Billions
 12 Months Ended
Dec. 31, 2018
CAD ($)
Dec. 31, 2018
USD ($)
Dec. 31, 2017
CAD ($)
Dec. 31, 2017
USD ($)
Jan. 01, 2017
CAD ($)
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Outstanding settlements payable $ 45   $ 39   $ 43
Prepaid and other current assets 260   310   172
Trade accounts payable and other liabilities 2,333   2,290   $ 1,870
Free-standing derivatives not designated as hedging Instruments [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Prepaid and other current assets 2        
Trade accounts payable and other liabilities 6        
Hedges of net investment in foreign operations [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Foreign operations was designated in a net investment hedging relationship   $ 2.6   $ 4.1  
Foreign exchange translation on investment in foreign operations 295   387    
Sale and purchase contracts [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Outstanding settlements receivable 557   687    
Outstanding settlements payable 45   39    
Embedded derivatives [member] | Notes Due 2024 [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Fair value of embedded derivative 73   108    
Embedded derivatives [member] | Contingent Zinc Escalation Payment Embedded Derivative [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Fair value of embedded derivative 34   43    
Gold Stream Embedded Derivative [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Fair value of embedded derivative $ 11   9    
Percentage of ongoing payment containing embedded derivative 15.00% 15.00%      
Silver Stream Embedded Derivative [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Percentage of ongoing payment containing embedded derivative 5.00% 5.00%      
Fair value of embedded derivative $ 1   3    
Notes Due 2024 [member] | Derivatives not designated as hedging instruments and embedded derivatives [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Gain on non-operating income (expense) $ (42)   $ 51    
Currency risk [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Strengthening/Weakening of Canadian dollar against the U.S. dollar 0.10 0.10 0.10 0.10  
Pre-tax loss (gain) from financial instruments due to foreign currency translation $ 8   $ 3    
Pre-tax loss (gain) in other comprehensive income from translation of foreign operations 408   157    
Interest rate risk [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Pre-tax gain (loss) from financial instruments due to interest rate change $ 15   $ 10    
Percentage decrease in commodity price risk 1.00% 1.00% 1.00% 1.00%  
Commodity Price Risk [member]          
Disclosure of nature and extent of risks arising from financial instruments [line items]          
Pre-tax gain (loss) from financial instruments due to interest rate change $ 16   $ 26    
Percentage of change in commodity price 10.00% 10.00%