Gains And Losses On Asset Sales (Detail) (CAD) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Investment And Other Income [Line Items]
Proceeds from asset sales	61	6	139	20
Book value of assets sold	6	6	55	14
Gain/(loss) on asset sales, before tax	55		84	6
Gain/(loss) on asset sales, after tax	46		70	4