Segmented Information - Schedule of Segment Information for Reporting Segments and a Reconciliation for Adjusted EBIT to Consolidated Income Before Income Taxes (Parenthetical) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Segment Reporting [Abstract]
Net Income from operations	$ 2,255	$ 2,074
Add (deduct):
Interest expense, net	70	88
Other expense, net	39	30
Income taxes	744	706
Adjusted EBIT	$ 3,108	$ 2,898

Segmented Information - Schedule of Segment Information for Reporting Segments and a Reconciliation for Adjusted EBIT to Consolidated Income Before Income Taxes (Parenthetical) (Detail) - USD ($)
$ in Millions

12 Months Ended

Dec. 31, 2017

Dec. 31, 2016

Segment Reporting [Abstract]

Net Income from operations

$ 2,255

$ 2,074

Add (deduct):

Interest expense, net

Other expense, net

Income taxes

744

706

Adjusted EBIT

$ 3,108

$ 2,898