Stock-Based Compensation (Stock Options Outstanding, Exercisable and Activity) (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Number of Shares
Beginning Balance	3,729,728
Granted	792,079
Exercised	(611,091)
Forfeited/Expired	(29,150)
Ending Balance	3,881,566	3,729,728
Vested or expected to vest, at end of period	3,657,738
Exercisable, at end of period	1,859,345
Weighted Average Exercise Price
Beginning Balance (in dollars per share)	$ 67.68
Granted (in dollars per share)	95.29
Exercised (in dollars per share)	50.08
Forfeited/Expired (in dollars per share)	100.22
Ending Balance (in dollars per share)	75.84	$ 67.68
Vested or expected to vest, at end of period (in dollars per share)	66.90
Exercisable, at end of period (in dollars per share)	$ 48.43
Weighted Average Remaining Contractual Life (in years)
Outstanding	6 years 6 months	6 years 6 months
Vested or expected to vest, at end of period	6 years 5 months
Exercisable, at end of period	4 years 7 months
Intrinsic Value (in millions)
Outstanding	$ 86	$ 127
Vested or expected to vest, at end of period	86
Exercisable, at end of period	$ 86