Corporate Income Taxes - Additional Information (Detail) - CAD ($) $ in Millions |
Apr. 30, 2026 |
Jan. 31, 2026 |
|---|---|---|
| 2014 to 2019 taxation year [member] | Subsidiaries [member] | ||
| Disclosure Of Income Taxes [Line Items] | ||
| Subsidiary amount for tax assessment notice served | $ 637 | $ 637 |
| 2011 to 2020 taxation year [member] | ||
| Disclosure Of Income Taxes [Line Items] | ||
| Reassessed tax by Canada Revenue Agency | 1,808 | $ 1,808 |
| 2018 to 2020 taxation year [member] | Subsidiaries [member] | ||
| Disclosure Of Income Taxes [Line Items] | ||
| Subsidiary amount for tax assessment notice served | $ 4 |