Investment and other income - Gains and Losses on Asset Sales (Detail) - CAD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Other Income and Expenses [Abstract] | |||
| Proceeds from asset sales | $ 101 | $ 25 | $ 86 |
| Book value of asset sales | 106 | 7 | 13 |
| Gain (loss) on asset sales, before-tax | (5) | 18 | 73 |
| Gain (loss) on asset sales, after-tax | $ (9) | $ 16 | $ 63 |