Capital Stock - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		46 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017
Equity [Abstract]
Options and restricted stock, anti-dilutive	8,400,000	7,100,000
Dividends, common stock	$ 95	$ 95
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