Shareholders' Equity - Activities Under Shares Repurchase Program (Detail) CAD / shares in Units, CAD in Millions	12 Months Ended
Dec. 31, 2015 CAD CAD / shares shares
Statement of Stockholders' Equity [Abstract]
Number of Common Shares repurchased \| shares	13,549,977
Weighted-average price per share (in dollars per share) \| CAD / shares	CAD 202.79
Amount of repurchase \| CAD	CAD 2,748

The number of shares authorized to be repurchased by an entity's Board of Directors under a stock repurchase plan.

No definition available.

Name:	us-gaap_StockRepurchaseProgramNumberOfSharesAuthorizedToBeRepurchased
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant