Earnings Per Common Share (Details) - CAD CAD / shares in Units, shares in Millions, CAD in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Earnings Per Common Share
Net earnings	CAD 4,458.0	CAD 445.0
Dilutive impact of accounting for awards as equity settled	(1.0)	(1.0)
Net earnings - diluted	4,457.0	444.0
Net earnings attributable to common shareholders	4,458.0	434.0
Net earnings - diluted attributable to common shareholders	CAD 4,457.0	CAD 433.0
Weighted average number of common shares	1,661.0	1,610.0
Dilutive Securities:
Effect of share options	4.0	2.0
Weighted average number of diluted common shares	1,665.0	1,612.0
Net earnings - basic and diluted	CAD 2.68	CAD 0.28
Basic and diluted earnings per share attributable to common shareholders	CAD 2.68	CAD 0.27

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 earnings per share when the basic and diluted measurements are equal. [Refer: Basic earnings (loss) per share; Diluted earnings (loss) per share]

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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 total of income less expenses, excluding the components of other comprehensive income. [Refer: Other comprehensive income]

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

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