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Decommissioning and Other Provisions - Change in Decommissioning and Other Provision Balances (Details) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2021 | Dec. 31, 2020
Reconciliation of changes in other provisions [abstract] |  |
Balance | $ 673 | $ 546
Liabilities incurred | 30 | 35
Liabilities settled | (80) | (37)
Accretion | (32) | 30
Acquisition of liabilities | 2 | 1
Revisions in estimated cash flows | 179 | 72
Revisions in discount rates | (6) | 36
Reversals | (3) | (6)
Change in foreign exchange rates |  | (4)
Balance | $ 827 | 673
Minimum |  |
Reconciliation of changes in other provisions [abstract] |  |
Increase (decrease) in discount rates, other provisions | (0.30%) |
Maximum |  |
Reconciliation of changes in other provisions [abstract] |  |
Increase (decrease) in discount rates, other provisions | (0.90%) |
Decommissioning and restoration |  |
Reconciliation of changes in other provisions [abstract] |  |
Balance | $ 608 | 501
Liabilities incurred | 8 | 1
Liabilities settled | (18) | (18)
Accretion | (32) | 30
Acquisition of liabilities | 2 | 1
Revisions in estimated cash flows | 167 | 61
Revisions in discount rates | (6) | 36
Reversals | 0 | 0
Change in foreign exchange rates |  | (4)
Balance | 793 | 608
Other provisions |  |
Reconciliation of changes in other provisions [abstract] |  |
Balance | 65 | 45
Liabilities incurred | 22 | 34
Liabilities settled | (62) | (19)
Accretion | 0 | 0
Acquisition of liabilities | 0 | 0
Revisions in estimated cash flows | 12 | 11
Revisions in discount rates | 0 | 0
Reversals | (3) | (6)
Change in foreign exchange rates |  | 0
Balance | $ 34 | $ 65

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- Definition The increase in other provisions resulting from acquisitions through business combinations. [Refer: Business combinations [member]; Other provisions] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 37 -IssueDate 2021-01-01 -Paragraph 84 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2021-en-r&anchor=para_84&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The increase (decrease) in other provisions resulting from a change in discount rate. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 37 -IssueDate 2021-01-01 -Paragraph 84 -Subparagraph e -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2021-en-r&anchor=para_84_e&doctype=Standard -URIDate 2021-03-24 + Details
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- Definition The increase (decrease) in other provisions resulting from foreign currency exchange rate changes on provisions measured in a currency different from the entity's presentation currency. [Refer: Other provisions] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 37 -IssueDate 2021-01-01 -Paragraph 84 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2021-en-r&anchor=para_84&doctype=Standard -URIDate 2021-03-24 + Details
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