Share-Based Compensation - Summary of Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2015 USD ($) $ / shares shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding stock options, Beginning balance | shares	7,846
Options granted | shares	1,717
Options exercised | shares	(1,404)
Options forfeited | shares	(185)
Options expired | shares	(43)
Outstanding stock options, Ending Balance | shares	7,931
Number of outstanding options, Vested or expected to vest | shares	7,497
Exercisable, Stock options | shares	4,969
Outstanding Weighted average exercise price, Beginning Balance | $ / shares	$ 71.94
Options granted, Weighted average exercise price | $ / shares	107.10
Options exercised, Weighted average exercise price | $ / shares	73.09
Options forfeited, Weighted average exercise price | $ / shares	97.02
Options expired, Weighted average exercise price | $ / shares	80.59
Outstanding Weighted average exercise price, ending Balance | $ / shares	78.73
Outstanding Weighted average exercise price, Vested or expected to vest | $ / shares	77.59
Exercisable, Weighted average exercise price | $ / shares	$ 68.67
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2015	5 years 8 months 12 days
Weighted Average Remaining Contractual Life, Vested or expected to vest as of December 31, 2015	5 years 6 months
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2015	3 years 10 months 24 days
Intrinsic Value, Outstanding at December 31, 2015 | $	$ 201.1
Intrinsic Value, Vested or expected to vest as of December 31, 2015 | $	197.4
Intrinsic Value, Exercisable at December 31, 2015 | $	$ 168.6