Equity - Summary of Basic and Diluted Earnings Per Share (Detail) - CAD ($) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Equity [abstract]
Net basic and diluted profit (loss) attributable to shareholders of the company	$ (605)	$ 3,107
Weighted average shares outstanding (in shares)	559,765	573,905
Dilutive effect of share options (in shares)	0	8,233
Weighted average diluted shares outstanding (in shares)	559,765	582,138
Basic earnings (loss) per share (in dollars per share)	$ (1.08)	$ 5.41
Diluted earnings (loss) per share (in dollars per share)	$ (1.08)	$ 5.34

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 number of dilutive potential ordinary shares that relate to the assumed exercise of the entity's share options.

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

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The number of ordinary shares outstanding at the beginning of the period, adjusted by the number of ordinary shares bought back or issued during the period multiplied by a time-weighting factor.

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