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Property, Plant and Equipment - Narrative (Details) shares in Millions, $ in Millions | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | ---
Dec. 31, 2018 CAD ($) | Dec. 31, 2019 CAD ($) | Dec. 31, 2018 CAD ($) | Dec. 31, 2017 CAD ($) | Jun. 27, 2019 CAD ($) | May 31, 2017 USD ($) shares | May 31, 2017 CAD ($) shares
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Revaluation pre-tax gain |  |  | $ 19,000,000 |  |  |  |
Return of asset retirement obligations upon disposal of property | $ 69,000,000 |  | 69,000,000 |  |  |  |
Disposals of property, plant and equipment pre-tax gain | 20,000,000 |  |  |  |  |  |
Disposals of property, plant and equipment after-tax gain | 14,000,000 |  |  |  |  |  |
Interest costs capitalized |  | $ 53,000,000 | $ 69,000,000 | $ 82,000,000 |  |  |
Weighted average capitalization rate |  | 4.00% | 3.90% | 3.80% |  |  |
Revenue |  | $ 22,871,000,000 | $ 21,027,000,000 | $ 17,342,000,000 |  |  |
Revenue net of blending, production, transportation, and feedstock expense |  | 11,895,000,000 |  |  |  |  |
North America |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Net cash paid for consideration for acquisition of exploration and evaluation assets |  | 80,000,000 | 170,000,000 | 1,013,000,000 |  |  |
Exploration and evaluation assets |  |  |  | 27,000,000 |  |  |
Asset retirement obligations | 13,000,000 | 20,000,000 | 13,000,000 | 63,000,000 |  |  |
Deferred tax liabilities | 0 | 0 | 0 | 0 |  |  |
Gains on acquisitions of property, plant and equipment, pre-tax |  | 0 | 47,000,000 | 0 |  |  |
Project costs not subject to depletion and depreciation | 1,424,000,000 |  | 1,424,000,000 |  |  |  |
North Sea |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Asset retirement obligations | 41,000,000 |  | 41,000,000 |  |  |  |
Deferred tax liabilities | 27,000,000 |  | 27,000,000 |  |  |  |
Gains on acquisitions of property, plant and equipment, pre-tax |  |  | 120,000,000 |  |  |  |
Property, plant and equipment acquisition |  |  | 108,000,000 |  |  |  |
Net proceeds received for acquisition of property, plant and equipment |  |  | 73,000,000 |  |  |  |
Net working capital assets recognised, property, plant and equipment acquisition | $ 7,000,000 |  | 7,000,000 |  |  |  |
Revaluation pre-tax gain |  |  | $ 19,000,000 |  |  |  |
Midstream and Refining |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Revaluation pre-tax gain |  |  |  | 114,000,000 |  |  |
Revaluation after-tax gain |  |  |  | 83,000,000 |  |  |
Oil Sands Mining and Upgrading |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Project costs not subject to depletion and depreciation |  | 115,000,000 |  |  |  |  |
Devon |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Exploration and evaluation assets |  |  |  |  | $ 91,000,000 |  |
Asset retirement obligations |  |  |  |  | 178,000,000 |  |
Total purchase consideration |  |  |  |  | $ 3,412,000,000 |  |
Revenue of acquiree since acquisition date |  | 1,540,000,000 |  |  |  |  |
Revenue net of blending, production, transportation, and feedstock expense |  | 590,000,000 |  |  |  |  |
AOSP |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Total purchase consideration |  |  |  |  |  |  | $ 12,541,000,000
Interest acquired |  |  |  |  |  | 70.00% | 70.00%
Cash transferred |  |  |  |  |  |  | $ 8,217,000,000
Number of instruments or interests issued or issuable | shares |  |  |  |  |  | 97.6 | 97.6
Equity interests of acquire |  |  |  | 3,818,000,000 |  |  | $ 3,818,000,000
Liabilities incurred |  |  |  |  |  | $ 375 | $ 506,000,000
Gain on acquisition, net of transaction costs |  |  |  | 230,000,000 |  |  |
Acquisition related transaction costs |  |  |  | $ 3,000,000 |  |  |
AOSP, Mining And Extraction Operations |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Interest acquired |  |  |  |  |  | 70.00% | 70.00%
AOSP, Scotford Upgrader And Quest Carbon Capture And Storage Project |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Interest acquired |  |  |  |  |  | 70.00% | 70.00%
AOSP, Peace River Thermal In Situ Operations And Cliffdale Heavy Oil Field |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Interest acquired |  |  |  |  |  | 100.00% | 100.00%
Non-revolving term credit facility maturing June 2022 |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Maximum credit facility |  | 3,250,000,000 |  |  |  |  |
Pro Forma | Devon |  |  |  |  |  |  |
Disclosure of detailed information about property, plant and equipment [line items] |  |  |  |  |  |  |
Revenue net of blending, production, transportation, and feedstock expense |  | 670,000,000 |  |  |  |  |
Revenue net of blending expense |  | $ 1,010,000,000 |  |  |  |  |

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