v3.25.4
Contract costs (Details) - CAD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of disaggregation of revenue from contracts with customers [line items]    
Opening balance $ 1,590 $ 1,412
Incremental costs of obtaining a contract and contract fulfillment costs 1,035 969
Amortization included in operating costs (811) (791)
Dispositions (6) 0
Ending balance $ 1,808 $ 1,590
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