Business Segments (Parenthetical) (Detail) (CAD) In Millions, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2013		Jun. 30, 2012		Jun. 30, 2013		Jun. 30, 2012
Segment Reporting Information [Line Items]
Operating revenues	7,894	[1],[2],[3]	7,452	[1],[2],[3]	15,893	[1],[2],[4]	14,946	[1],[2],[4]
Write-down of refinery plant and equipment reported as depreciation and depletion expenses	245				245
Decommissioning, environmental and employee-related costs reported as production and manufacturing expenses	110				110
Pre Tax
Segment Reporting Information [Line Items]
Charges related to conversion of refinery to terminal	355				355
After Tax
Segment Reporting Information [Line Items]
Charges related to conversion of refinery to terminal	264				264
United States Exports
Segment Reporting Information [Line Items]
Operating revenues	1,306		1,133		2,691		2,038

[1] Federal excise tax included in operating revenues 330 340 656 656

[2] Amounts from related parties included in operating revenues 364 938 1,225 1,645

[3] Includes export sales to the United States of $1,306 million (2012- $1,133 million). Export sales to the United States were recorded in all operating segments, with the largest effects in the Upstream segment.

[4] Includes export sales to the United States of $2,691 million (2012- $2,038 million). Export sales to the United States were recorded in all operating segments, with the largest effects in the Upstream segment.