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SEGMENTED INFORMATION - Narrative (Details)	12 Months Ended
	Dec. 31, 2017 segment
Operating Segments [Abstract]
Number of geographic segments	3

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- Definition

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X

- Definition

Operating Segments [Abstract]

+ References

No definition available.

+ Details

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Namespace Prefix:	cnq_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration