XML 180 R103.htm IDEA: XBRL DOCUMENT v3.20.4
Contract costs (Details) - CAD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Revenue From Contract With Customer1 [Abstract]    
Opening balance $ 783 $ 707
Incremental costs of obtaining a contract and contract fulfillment costs 535 602
Amortization included in operating costs (552) (523)
Impairment charges included in operating costs 0 (3)
Discontinued operations (2) 0
Ending balance $ 764 $ 783
Bottom of range    
Disclosure of disaggregation of revenue from contracts with customers [line items]    
Contract costs, amortization period 12 months  
Top of range    
Disclosure of disaggregation of revenue from contracts with customers [line items]    
Contract costs, amortization period 84 months