v3.22.4
Debt (Notes and debentures) (Details)
$ in Millions, $ in Millions
Nov. 15, 2022
USD ($)
Nov. 15, 2022
CAD ($)
Aug. 05, 2022
CAD ($)
Sep. 15, 2021
USD ($)
Sep. 15, 2021
CAD ($)
Jan. 18, 2021
CAD ($)
Dec. 31, 2022
Aug. 05, 2022
USD ($)
Aug. 05, 2022
CAD ($)
Debt Instrument [Line Items]                  
Proceeds from debt issuance     $ 1,901            
Cumulative loss     $ 2            
Treasury Lock [Member]                  
Debt Instrument [Line Items]                  
Notional amount               $ 675 $ 868
Canadian National series, 2.25% 10-year notes [Member]                  
Debt Instrument [Line Items]                  
Interest rate 2.25% 2.25%         2.25%    
Repayment of debt $ 250 $ 332              
Canadian National series, 3.85% 10-year notes [Member]                  
Debt Instrument [Line Items]                  
Debt issued, face amount               $ 800 $ 1,028
Interest rate             3.85% 3.85% 3.85%
Canadian National series, 4.40% 30-year notes [Member]                  
Debt Instrument [Line Items]                  
Debt issued, face amount               $ 700 $ 900
Interest rate             4.40% 4.40% 4.40%
Canadian National series, 2.85% 10-year notes [Member]                  
Debt Instrument [Line Items]                  
Interest rate       2.85% 2.85%        
Repayment of debt       $ 400 $ 506        
Canadian National series, 2.75% 7-year notes [Member]                  
Debt Instrument [Line Items]                  
Interest rate           2.75%      
Repayment of debt           $ 250