Common Share Activities (Detail) (CAD) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended			192 Months Ended	216 Months Ended
	Dec. 31, 2012		Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2013
Class of Stock [Line Items]
Common stock beginning balance, shares	847,599		847,599
Issued under employee share-based awards	2,776		1,262
Purchases at stated value, shares	(2,776)		(1,262)	(903,765)	(906,541)
Common stock, ending balance, shares	847,599		847,599	847,599	847,599
Common stock beginning balance, value	1,528		1,511
Issued under employee share-based awards, value	43		19
Purchases at stated value, value	(128)			(15,580)	(15,708)
Common stock, ending balance, value	1,566	[1]	1,528	1,528	1,566	[1]
Common Stock
Class of Stock [Line Items]
Purchases at stated value, value	(5)		(2)

[1] Number of common shares outstanding was 848 million (2012 - 848 million), (note 10).