v3.19.2
other long-term assets - Costs incurred to obtain and fulfill contracts with customers (Details) - CAD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2019
Jun. 30, 2019
Dec. 31, 2018
Disclosure of assets recognised from costs to obtain or fulfil contracts with customers [line items]        
Balance, beginning of period $ 357 $ 371    
Additions 71 133    
Amortization (76) (152)    
Balance, end of period 352 352    
Current     $ 247  
Non-current     105 $ 110
Total 357 371 352 371
Costs incurred to obtain contracts with customers        
Disclosure of assets recognised from costs to obtain or fulfil contracts with customers [line items]        
Balance, beginning of period 342 356    
Additions 70 131    
Amortization (75) (150)    
Balance, end of period 337 337    
Current     242  
Non-current     95  
Total 342 356 337 356
Costs incurred to fulfill contracts with customers        
Disclosure of assets recognised from costs to obtain or fulfil contracts with customers [line items]        
Balance, beginning of period 15 15    
Additions 1 2    
Amortization (1) (2)    
Balance, end of period 15 15    
Current     5  
Non-current     10  
Total $ 15 $ 15 $ 15 $ 15