Shareholders' Equity (Parenthetical) (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Equity [Abstract]
Tax expense, retirement benefits	$ 9	$ 25	$ 5	$ 21
Tax expense, long-term investments		2		3
Tax expense, hedging instruments				6
Tax expense, cumulative translation adjustment and other	$ 5	$ (2)	$ 6	$ 9
Dividends, per share	$ 0.51	$ 0.42	$ 1.02	$ 0.84