Results of Share Repurchase Program 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
Schedule Of Common Share Purchase [Line Items]
Cumulative purchases to date, shares	2,776	1,262	903,765	906,541
Cumulative purchases to date, value	128		15,580	15,708

Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30, 31

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration