v3.25.4
Net gains on investments (Details) - CAD ($)
$ in Millions
3 Months Ended 12 Months Ended
Jul. 01, 2025
Dec. 31, 2025
Dec. 31, 2027
Dec. 31, 2025
Dec. 31, 2024
Oct. 01, 2025
Subsidiaries            
Disclosure of analysis of single amount of discontinued operations [line items]            
Gain recognised on disposal of assets or disposal groups constituting discontinued operation         $ 69  
Home Security and Monitored Alarm Assets | Assets and liabilities classified as held for sale            
Disclosure of analysis of single amount of discontinued operations [line items]            
Total proceeds from sale of operations   $ 170   $ 170   $ 170
Proceeds from sale of operations   $ 65   65    
Gain recognised on disposal of assets or disposal groups constituting discontinued operation       57    
Home Security and Monitored Alarm Assets | Assets and liabilities classified as held for sale | Forecast            
Disclosure of analysis of single amount of discontinued operations [line items]            
Additional proceeds from disposal of non-current assets to be received upon contingent consideration     $ 25      
Home Security and Monitored Alarm Assets | Assets and liabilities classified as held for sale | Forecast | Top of range            
Disclosure of analysis of single amount of discontinued operations [line items]            
Additional proceeds from disposal of non-current assets to be received upon contingent consideration     $ 80      
MSLE            
Disclosure of analysis of single amount of discontinued operations [line items]            
Proceeds from sale of operations       4,700    
Gain recognised on disposal of assets or disposal groups constituting discontinued operation       5,200    
Income tax liability $ 542     $ 542