Major Commitments and Contingencies (Contingencies) (Details) - Personal Injury and Other Claims Provision [Member] - CAD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2022 |
Dec. 31, 2021 |
Dec. 31, 2020 |
|
| Canada [Member] | |||
| Loss Contingency [Abstract] | |||
| Increase (decrease) to personal injury and other claims provision pursuant to the results of external actuarial studies | $ (11) | $ (11) | $ (13) |
| Loss Contingency Accrual [Roll Forward] | |||
| Beginning of year | 182 | 206 | 207 |
| Accruals and other | 16 | 12 | 31 |
| Payments | (30) | (36) | (32) |
| End of year | 168 | 182 | 206 |
| Current portion - End of year | 27 | 50 | 68 |
| U.S. [Member] | |||
| Loss Contingency [Abstract] | |||
| Increase (decrease) to personal injury and other claims provision pursuant to the results of external actuarial studies | (9) | (20) | (10) |
| Loss Contingency Accrual [Roll Forward] | |||
| Beginning of year | 125 | 141 | 145 |
| Accruals and other | 33 | 30 | 28 |
| Payments | (39) | (45) | (29) |
| Foreign exchange | 9 | (1) | (3) |
| End of year | 128 | 125 | 141 |
| Current portion - End of year | $ 18 | $ 25 | $ 41 |