Other Comprehensive (Loss) Income and Shareholders' Equity - Changes in Shareholders' Equity (Deficit) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5,357
Balance at beginning of period (in shares)	386.1
Net income	$ 365	$ 219
Other comprehensive income	185	19
Dividends ($0.30 per share)	(116)
Employee stock plan	$ (48)
Employee stock plan (in shares)	1.6
Purchase of treasury stock	$ (575)
Purchase of treasury stock (in shares)	(6.7)
Balance at end of period	$ 5,168
Balance at end of period (in shares)	381.0
Cash dividends (in USD per share)	$ 0.30
Class A Common Stock
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	$ 5
Balance at end of period	5
Additional Paid-in- Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	5,808
Employee stock plan	(97)
Balance at end of period	5,711
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	6,501
Net income	365
Dividends ($0.30 per share)	(116)
Balance at end of period	6,750
Treasury Stock, at Cost
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(6,460)
Employee stock plan	49
Purchase of treasury stock	(575)
Balance at end of period	(6,986)
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at beginning of period	(497)	(196)
Other comprehensive income	185
Balance at end of period	$ (312)	$ (177)