Other Long-Term Liabilities - Future Cash Outflow Required to Settle Its Asset Retirement Obligations (Details) - CAD ($) $ in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Subclassifications of assets, liabilities and equities [abstract] | ||
| Discount rate, 1% increase | $ (896) | $ (883) |
| Discount rate, 1% Decrease | 1,135 | 1,132 |
| Inflation rate, 1% increase | 1,171 | 1,166 |
| Inflation rate, 1% decrease | $ (934) | $ (920) |