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Financial Instruments - Net (Gains) Losses from Risk Management Activities (Details) - CAD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financial Instruments [Abstract]
Net realized risk management loss (gain)	$ 64	$ (99)	$ (2)
Net unrealized risk management loss (gain)	13	(35)	37
Gains (losses) on change in fair value of derivatives	$ 77	$ (134)	$ 35

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- Definition

Financial Instruments [Abstract]

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No definition available.

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- Definition

Gain (Losses) On Change In Fair Value Of Settled Derivatives

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- Definition

Gain (Losses) On Change In Fair Value Of Unsettled Derivatives

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No definition available.

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The gains (losses) resulting from change in the fair value of derivatives recognised in profit or loss. [Refer: Derivatives [member]]

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Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Name IAS
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-IssueDate 2019-01-01
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-URIDate 2019-03-27

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