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Significant Events - Asset Acquisitions (Details) - Keephills 3 - CAD ($) $ in Millions		12 Months Ended
	Oct. 01, 2019	Dec. 31, 2019
Investment [Line Items]
Working capital	$ 11
Property, plant and equipment	308	$ 308
Other assets	3
Other liabilities	2
Decommissioning and other provisions	19
Total acquisition cost	$ 301

X

- Definition

The amount of additions to property, plant and equipment other than those acquired through business combinations. [Refer: Business combinations [member]; Property, plant and equipment]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 16
-IssueDate 2018-01-01
-Paragraph 73
-Subparagraph e
-Clause i
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=16&date=2018-03-01&anchor=para_73_e_i&doctype=Standard
-URIDate 2018-03-16

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X

- Definition

Line items represent reporting concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 12
-Sentence Column A

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- Definition

Asset Acquisition, Assets Acquired and Liabilities Assumed, Net

+ References

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- Definition

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+ References

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- Definition

Asset Acquisition, Liabilities, Other

+ References

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- Definition

Asset Acquisition, Provision For Decommissioning, Restoration And Rehabilitation Costs

+ References

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- Definition

Asset Acquisition, Working Capital

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