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Inventory Components of Inventory (Details) - CAD ($) $ in Millions | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | ---
Disclosure of inventories [Abstract] |  |  |
Parts and materials | $ 108 | $ 113 |
Coal | 130 | 108 |
Deferred stripping costs | 6 | 7 |
Natural gas | 3 | 4 |
Purchased emission credits | 4 | 10 |
Inventories | $ 251 | $ 242 | $ 219

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- Definition A classification of current inventory representing the amount of a naturally occurring hydrocarbon gas mixture. [Refer: Inventories] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 2 -IssueDate 2018-01-01 -Paragraph 37 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_37&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition The amount of current inventories. [Refer: Inventories] + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 2 -IssueDate 2018-01-01 -Paragraph 36 -Subparagraph b -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_36_b&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 54 -Subparagraph g -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_54_g&doctype=Standard -URIDate 2018-03-16 Reference 3: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 68 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_68&doctype=Standard -URIDate 2018-03-16 + Details
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- Definition A classification of current inventory representing the amount of supplies to be used for the production process. [Refer: Inventories] + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Name IAS -Number 2 -IssueDate 2018-01-01 -Paragraph 37 -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=2&date=2018-03-01&anchor=para_37&doctype=Standard -URIDate 2018-03-16 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Name IAS -Number 1 -IssueDate 2018-01-01 -Paragraph 78 -Subparagraph c -URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=1&date=2018-03-01&anchor=para_78_c&doctype=Standard -URIDate 2018-03-16 + Details
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