Earnings (Loss) Per Share - Calculation of Basic and Diluted Earnings Per Share (Details) - CAD ($) $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
Dec. 31, 2021	Dec. 31, 2020
Earnings per share [line items]
Common shareholders' net income (loss) for basic earnings per share	$ 3,934	$ 2,404
Add: Increase in income due to convertible instruments	10	10
Common shareholders’ net income (loss) on a diluted basis	$ 3,944	$ 2,414
Weighted average number of common shares outstanding for basic earnings per share (in shares)	586	585
Add: Dilutive impact of stock options (in shares)	0	0
Dilutive impact of convertible instruments (in shares)	4	4
Weighted average number of common shares outstanding on a diluted basis (in shares)	590	589
Basic earnings (loss) per share (in CAD per share)	$ 6.72	$ 4.11
Diluted earnings (loss) per share (in CAD per share)	$ 6.69	$ 4.10
Stock Option
Earnings per share [line items]
Stock options excluded from computation of earnings per share (in shares)	1	1

The weighted average number of ordinary shares outstanding plus the weighted average number of ordinary shares that would be issued on the conversion of all the dilutive potential ordinary shares into ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator) divided by the weighted average number of ordinary shares outstanding during the period (the denominator).

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The amount of profit (loss) attributable to ordinary equity holders of the parent entity (the numerator), divided by the weighted average number of ordinary shares outstanding during the period (the denominator), both adjusted for the effects of all dilutive potential ordinary shares. [Refer: Ordinary shares [member]; Weighted average [member]]

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The profit (loss) attributable to ordinary equity holders of the parent entity. [Refer: Profit (loss)]

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The profit (loss) attributable to ordinary equity holders of the parent entity, adjusted for the effects of all dilutive potential ordinary shares. [Refer: Profit (loss)]

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