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Other Long-Term Liabilities - Asset Retirement Obligations (Details) - CAD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Disclosure of other provisions [line items] |  |  |
Asset retirement obligations settlement period | 60 years |  |
Inflation rate | 2.00% | 2.00% |
Reconciliation Of Changes In Provision For Decommissioning Restoration And Rehabilitation Costs [Roll Forward] |  |  |
Balance – beginning of year | $ 3,886 | $ 4,327 | $ 3,243
Balance – end of year | 5,771 | 3,886 | 4,327
Less: current portion | 208 | 186 | 92
Non-current asset retirement obligation | $ 5,563 | $ 3,700 | $ 4,235
Provision for decommissioning, restoration and rehabilitation costs [member] |  |  |
Disclosure of other provisions [line items] |  |  |
Weighted average discount rate | 3.80% | 5.00% | 4.70%
Reconciliation Of Changes In Provision For Decommissioning Restoration And Rehabilitation Costs [Roll Forward] |  |  |
Liabilities incurred | $ 15 | $ 19 | $ 12
Liabilities acquired, net | 198 | 6 | 784
Liabilities settled | (296) | (290) | (274)
Asset retirement obligation accretion | 190 | 186 | 164
Revision of cost, inflation rates and timing estimates | 412 | (111) | (40)
Change in discount rates | 1,412 | (334) | 509
Foreign exchange adjustments | $ (46) | $ 83 | $ (71)

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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 2019-01-01 -Paragraph 84 -URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2019-en-r&anchor=para_84&doctype=Standard -URIDate 2019-03-27 + Details
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