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NET EARNINGS (LOSS) PER COMMON SHARE - Narrative (Details) shares in Thousands | 12 Months Ended
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Dec. 31, 2017 shares
Earnings per share [abstract] |
Potentially anti-dilutive securities | 17,547

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- Definition Antidilutive Securities Excluded From Computation Of Earnings Per Share, Amount1 + References No definition available. + Details
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Namespace Prefix: | cnq_
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Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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Namespace Prefix: | ifrs-full_
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Balance Type: | na
Period Type: | duration