Other Comprehensive (Loss) Income and Shareholders' (Deficit) Equity - Changes in Shareholders' Deficit (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	$ (3,590)
Balance at year-end 2015, shares	256.3
Net income	$ 219	$ 207
Other comprehensive income	19	$ (20)
Cash dividends ($0.25 per share)	(64)
Employee stock plan	$ (26)
Employee stock plan, shares	1.6
Purchase of treasury stock	$ (225)
Purchase of treasury stock, shares	(3.7)
Balance at March 31, 2016	$ (3,667)
Balance at March 31, 2016, shares	254.2
Cash dividends, per share (in USD per share)	$ 0.25
Additional Paid-in- Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	$ 2,821
Employee stock plan	(70)
Balance at March 31, 2016	2,751
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	4,878
Net income	219
Cash dividends ($0.25 per share)	(64)
Employee stock plan	(8)
Balance at March 31, 2016	5,025
Treasury Stock, at Cost
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	(11,098)
Employee stock plan	52
Purchase of treasury stock	(225)
Balance at March 31, 2016	(11,271)
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	(196)
Other comprehensive income	19
Balance at March 31, 2016	(177)
Class A Common Stock
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2015	5
Balance at March 31, 2016	$ 5