Gains and Losses on Asset Sales (Parenthetical) (Detail) - CAD CAD in Billions	3 Months Ended	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2016
Investment And Other Income [Line Items]
Expected gain on Planned consideration on sale of remaining company-owned Esso retail	CAD 0.8	CAD 0.8
Expected gain on Planned consideration on sale of remaining company-owned Esso retail, net of tax	CAD 0.7	CAD 0.7