Financial and derivative instruments - Summary of realized and unrealized gain or (loss) on derivative instruments (Detail) - CAD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Derivative Instruments and Hedging Activities Disclosure [Abstract] | |||
| Revenues | $ 41 | $ (69) | $ (5) |