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Preferred Shares - Preferred Share Dividends Declared (Details) - CAD ($) $ / shares in Units, $ in Millions				12 Months Ended
	Jan. 26, 2020	Oct. 09, 2019	Dec. 14, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disclosure of classes of share capital [line items]
Dividends declared per share	$ 0.0425	$ 0.04	$ 0.04
Series A
Disclosure of classes of share capital [line items]
Dividends declared				$ 5	$ 9	$ 5
Series B
Disclosure of classes of share capital [line items]
Dividends declared				1	1	1
Series C
Disclosure of classes of share capital [line items]
Dividends declared				8	14	9
Series E
Disclosure of classes of share capital [line items]
Dividends declared				9	15	8
Series G
Disclosure of classes of share capital [line items]
Dividends declared				7	11	7
Preferred Shares
Disclosure of classes of share capital [line items]
Dividends declared				$ 30	$ 50	$ 30

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The amount, per share, of dividends proposed or declared before financial statements were authorised for issue but not recognised as distribution to owners.

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- Definition

The amount of dividends recognised as distributions to owners of the parent. [Refer: Parent [member]]

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