Other long-term obligations - Table Narrative (Detail) - CAD ($) $ in Millions |
Mar. 31, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Other Liabilities Disclosure [Abstract] | ||
| Employee retirement benefit obligations in current liabilities | $ 63 | $ 63 |
| Asset retirement obligations and other environmental liabilities in current liabilities | 318 | 318 |
| Lease liability due within one year, Operating leases | $ 77 | $ 87 |
| X | ||||||||||
- Definition Asset retirement obligation and other environmental liabilities current. No definition available.
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| X | ||||||||||
- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Amount of liability, recognized in statement of financial position, for defined benefit pension and other postretirement plans, classified as current. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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