Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
	Jun. 10, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Equity [Abstract]
Options and restricted stock, anti-dilutive		10,400,000	4,700,000	8,900,000	5,500,000
Dividends, Common stock		$ 95	$ 95	$ 283	$ 271
Common stock share purchase, shares		40,000,000		40,000,000
Common stock share repurchase, shares	32,200,000
Common stock share repurchase, per share	$ 88.96