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Decommissioning and Other Provisions - Decommissioning and Restoration - Narrative (Details) $ in Millions | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2022 CAD ($) | Dec. 31, 2021 CAD ($) | Dec. 31, 2020 CAD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($)
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Undiscounted cash amount | $ 1,600,000,000 |  |  |  |
Revisions in estimated cash flows | 100,000,000 | $ 179,000,000 |  |  |
Decrease in PP&E | (123,000,000) | (6,000,000) |  |  |
Reversal of impairment loss | (102,000,000) | 0 |  |  |
Revisions in discount rates | (225,000,000) | (6,000,000) |  |  |
Onerous contract provisions | 0 | (14,000,000) | $ (29,000,000) |  |
Decommissioning and restoration |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Revisions in estimated cash flows | 95,000,000 | 167,000,000 |  |  |
Decrease in PP&E | (49,000,000) | (133,000,000) |  |  |
Reversal of impairment loss |  | (34,000,000) |  |  |
Revisions in discount rates | (225,000,000) | (6,000,000) |  |  |
Gas And Energy Transition |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Decommissioning and restoration provision |  | (47,000,000) |  |  |
Minimum |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Revisions in discount rates | 7.0 | 3.6 |  |  |
Maximum |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Revisions in discount rates | 0.097 | 6.5 |  |  |
Gas |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Decommissioning and restoration provision | (46,000,000) |  |  |  |
Centralia Coal Mine |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Onerous contract provisions | (10,000,000) |  |  |  |
Centralia Coal Mine | Surety Bonds |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Bonds issued |  |  |  | $ 147 | $ 147
Alberta Mine | Letters Of Credit |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Bonds issued | 187,000,000 | 188,000,000 |  |  |
Royalty Contract |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Onerous contract provisions | (7,000,000) |  |  |  |
Wind Sites |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Decommissioning and restoration provision |  | $ (120,000,000) |  |  |
Decommissioning and restoration |  |  |  |  |
Disclosure of detailed information about borrowings [line items] |  |  |  |  |
Decommissioning and restoration provision | $ (225,000,000) |  |  |  |

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