Per Share Amounts - Schedule Representing Per Share Amounts (Detail) - CAD ($) $ / shares in Units, $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings (Loss) From:
Continuing Operations	$ (2,916)	$ 2,268	$ (459)
Discontinued Operations	247	1,098	(86)
Net Earnings (Loss)	$ (2,669)	$ 3,366	$ (545)
Basic - Weighted Average Number of Shares (millions)	1,228.8	1,102.5	833.3
Dilutive Effect of Cenovus NSRs	0.4
Diluted - Weighted Average Number of Shares	1,229.2	1,102.5	833.3
Basic and Diluted Earnings (Loss) Per Share ($)
Continuing Operations	$ (2.37)	$ 2.06	$ (0.55)
Discontinued Operations	0.20	0.99	(0.10)
Net Earnings (Loss) Per Share	$ (2.17)	$ 3.05	$ (0.65)

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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