Share-Based Compensation - Summary of Stock Option Activity (Detail) (USD $) In Millions, except Share data in Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Outstanding stock options, Beginning balance	10,741
Options granted	1,193
Options exercised	(3,811)
Options forfeited	(235)
Options expired	(42)
Outstanding stock options, Ending Balance	7,846
Number of outstanding options, Vested or expected to vest	7,485
Exercisable, Stock options	4,927
Outstanding Weighted average exercise price, Beginning Balance	$ 70.06
Options granted, Weighted average exercise price	$ 94.58
Options exercised, Weighted average exercise price	$ 73.55
Options forfeited, Weighted average exercise price	$ 75.84
Options expired, Weighted average exercise price	$ 71.25
Outstanding Weighted average exercise price, ending Balance	$ 71.94
Outstanding Weighted average exercise price, Vested or expected to vest	$ 71.47
Exercisable, Weighted average exercise price	$ 67.91
Weighted Average Remaining Contractual Life, Outstanding at December 31, 2014	5 years 6 months
Weighted Average Remaining Contractual Life, Vested or expected to vest as of December 31, 2014	5 years 4 months 24 days
Weighted Average Remaining Contractual Life, Exercisable at December 31, 2014	3 years 10 months 24 days
Intrinsic Value, Outstanding at December 31, 2014	$ 325.5
Intrinsic Value, Vested or expected to vest as of December 31, 2014	314.0
Intrinsic Value, Exercisable at December 31, 2014	$ 224.2