Period End Capitalized Suspended Exploratory Well Costs (Detail) (CAD) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized suspended exploratory well costs, total	173	167	163
Beginning Balance	167	163	120
Additions pending the determination of proved reserves	12	16	43
Charged to expense
Reclassification to wells, facilities and equipment based on the determination of proved reserves	(6)	(12)
Ending Balance	173	167	163
Capitalized for a period of one year or less	6	16	43
Capitalized For A Period Of Between One And Five Years
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized suspended exploratory well costs	167	151	120
Capitalized For A Period Of Greater Than One Year
Projects with Exploratory Well Costs Capitalized for More than One Year [Line Items]
Capitalized suspended exploratory well costs	167	151	120