v3.19.2
provisions (Details) - CAD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2019
Jun. 30, 2019
Dec. 31, 2018
provisions reconciliation        
Balance at beginning of period $ 763 $ 800    
Additions 43 80    
Reversal (1) (4)    
Use (23) (93)    
Interest effect 5 11    
Effects of foreign exchange, net (4) (11)    
Balance at end of period 783 783    
Current     $ 93  
Non-current     690  
Total 763 800 783 $ 800
As previously reported        
provisions reconciliation        
Balance at beginning of period   857    
Total   857   857
IFRS 16 effects        
provisions reconciliation        
IFRS 16, Leases transitional amount       (57)
Asset retirement obligation        
provisions reconciliation        
Balance at beginning of period 338 336    
Use (1) (2)    
Interest effect 2 5    
Balance at end of period 339 339    
Current     6  
Non-current     333  
Total 338 336 339 336
Asset retirement obligation | As previously reported        
provisions reconciliation        
Balance at beginning of period   336    
Total   336   336
Employee related        
provisions reconciliation        
Balance at beginning of period 57 88    
Additions 19 35    
Use (15) (62)    
Balance at end of period 61 61    
Current     56  
Non-current     5  
Total 57 88 61 88
Employee related | As previously reported        
provisions reconciliation        
Balance at beginning of period   88    
Total   88   88
Written put options        
provisions reconciliation        
Balance at beginning of period 277 290    
Reversal (1) (3)    
Use   (7)    
Interest effect 3 6    
Effects of foreign exchange, net (4) (11)    
Balance at end of period 275 275    
Non-current     275  
Total 277 290 275 290
Written put options | As previously reported        
provisions reconciliation        
Balance at beginning of period   290    
Total   290   290
Other        
provisions reconciliation        
Balance at beginning of period 91 86    
Additions 24 45    
Reversal   (1)    
Use (7) (22)    
Balance at end of period 108 108    
Current     31  
Non-current     77  
Total $ 91 86 $ 108 86
Other | As previously reported        
provisions reconciliation        
Balance at beginning of period   143    
Total   $ 143   143
Other | IFRS 16 effects        
provisions reconciliation        
IFRS 16, Leases transitional amount       $ (57)