Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended		31 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Equity [Abstract]
Options and restricted stock, anti-dilutive	6,300,000	8,300,000	7,400,000	8,300,000
Dividends, Common stock	$ 95	$ 95	$ 189	$ 189
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