Stock-Based Compensation - Additional Information (Detail) (USD $) In Millions, except Per Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee stock options, weighted average grant date fair value	$ 31.53
Employee Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Employee stock options, granted	0.3
Restricted stock, weighted average grant date fair value	$ 79.62
Unrecognized compensation expense	$ 9.9
Weighted average period to recognize expense	1 year 4 months
Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock, granted	0.9
Unrecognized compensation expense	96.2
Weighted average period to recognize expense	1 year 10 months
Non Market Performance Based Vesting Condition [Member] | Employee Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock, weighted average grant date fair value	$ 76.35
Unrecognized compensation expense	$ 17.8
Non Market Performance Based Vesting Condition [Member] | Restricted Stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Restricted stock, granted	0.2
Weighted average period to recognize expense	1 year 1 month 6 days