v3.26.1
Long term debt (Narrative) (Details)
 12 Months Ended
Jan. 13, 2025
USD ($)
Sep. 09, 2024
USD ($)
May 24, 2024
CAD ($)
Nov. 07, 2023
USD ($)
Dec. 31, 2025
CAD ($)
Dec. 31, 2024
CAD ($)
Disclosure of detailed information about borrowings [line items]            
Repayment of borrowings         $ 285,240,000 $ 1,041,590,000
Proceeds from debentures           497,022,000
Revolving Credit Facilities [Abstract]            
Unsecured revolving credit facility         1,000,000,000  
Maximum Letters of credit under the facility         100,000,000  
Increase in revolving credit facility with minimum Increments         50,000,000  
Maximum unsecured revolving credit facility         1,250,000,000  
Unsecured loans received         0 0
Outstanding letters of credit facility         1,529,574,000 1,527,815,000
Outstanding and committed letters of credit         $ 1,793,917,000 1,890,028,000
Debt to tangible net worth ratio         1  
Credit Facility Maturity         October 1, 2029  
Westinghouse Electric Company [Member]            
Disclosure of detailed information about borrowings [line items]            
Percent acquired in acquisition       49.00%    
US Term Loan [Member]            
Disclosure of detailed information about borrowings [line items]            
Proceeds of long-term debt       $ 600,000,000    
US Term Loan [Member] | Westinghouse Electric Company [Member] | Repayment Of Borrowings Transaction [Member]            
Disclosure of detailed information about borrowings [line items]            
Repayment of borrowings $ 200,000,000          
US Term Loan [Member] | Westinghouse Electric Company [Member] | Major Business Combination [Member]            
Disclosure of detailed information about borrowings [line items]            
Repayment of borrowings   $ 100,000,000        
US Term Loan, Tranche One [Member]            
Disclosure of detailed information about borrowings [line items]            
Proceeds of long-term debt       300,000,000    
US Term Loan Tranche Two [Member]            
Disclosure of detailed information about borrowings [line items]            
Proceeds of long-term debt       $ 300,000,000    
Series I [Member]            
Disclosure of detailed information about borrowings [line items]            
Effective interest rate     5.04%      
Interest rate     4.94%   4.94%  
Debenture issuance     $ 500,000,000   $ 497,630,000 $ 497,252,000
Proceeds from debentures     $ 497,000,000