v3.22.4
Stock-based Compensation (Employee Share Investment Plan) (Details)
$ / shares in Units, shares in Millions, $ in Millions
12 Months Ended
Dec. 31, 2022
CAD ($)
participant
$ / shares
shares
Dec. 31, 2021
CAD ($)
participant
$ / shares
shares
Dec. 31, 2020
participant
shares
Employee Share Investment Plan [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Maximum percentage of gross salary eligible employees can subscribe to purchase shares of Company's common stock on the open market 10.00%    
Maximum percentage of additional contribution made by the Company of amount invested by employee 35.00%    
Maximum percentage of gross salary employer can contribute toward purchase of Company's common stock 6.00%    
Vesting period 1 year    
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Units nonvested at beginning of period (in shares) 0.2    
Company contributions (in shares) 0.2    
Vested (in shares) (0.2)    
Forfeited (in shares) (0.1)    
Units nonvested at end of period (in shares) 0.1 0.2  
Weighted-average grant date fair value      
Weighted-average grant date fair value at beginning of period (in dollars per share) | $ / shares $ 142.80    
Company contributions (in dollars per share) | $ / shares 154.01    
Vested (in dollars per share) | $ / shares 142.34    
Forfeited (in dollars per share) | $ / shares 152.24    
Weighted-average grant date fair value at end of period (in dollars per share) | $ / shares $ 154.12 $ 142.80  
Fair value of units vested | $ $ 24 $ 17  
Unrecognized compensation costs, awards other than options | $ $ 8    
Unrecognized compensation cost, period of recognition 12 months    
Employee Share Investment Plan, Participants [Member]      
Weighted-average grant date fair value      
Number of participants holding shares | participant 19,967 20,142 20,270
Number of shares purchased on behalf of employees (in shares) 1.0 1.1 1.1