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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			$ (2,200)
Balance at year-end 2014, shares			279.9
Net income	$ 210	$ 192	$ 657	$ 556
Other comprehensive income	(32)	$ (14)	(50)	$ (9)
Cash dividends ($0.70 per share)			(189)
Employee stock plan			$ 40
Employee stock plan, shares			2.0
Purchase of treasury stock			$ (1,847)
Purchase of treasury stock, shares			(24.4)
Balance at September 30, 2015	$ (3,589)		$ (3,589)
Balance at September 30, 2015, shares	257.5		257.5
Cumulative adjustments to additional paid in capital, due to share-based compensation			$ 25
Cash dividends, per share (in USD per share)			$ 0.70
Additional Paid-in- Capital
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			$ 2,802
Employee stock plan			(11)
Balance at September 30, 2015	$ 2,791		2,791
Retained Earnings
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			4,286
Net income			657
Cash dividends ($0.70 per share)			(189)
Employee stock plan			(14)
Balance at September 30, 2015	4,740		4,740
Treasury Stock, at Cost
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			(9,223)
Employee stock plan			65
Purchase of treasury stock			(1,847)
Balance at September 30, 2015	(11,005)		(11,005)
Accumulated Other Comprehensive Loss
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			(70)
Other comprehensive income			(50)
Balance at September 30, 2015	(120)		(120)
Class A Common Stock
(Increase) Decrease in Shareholders' Deficit [Roll Forward]
Balance at year-end 2014			5
Balance at September 30, 2015	$ 5		$ 5