Summary of Options (Detail) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014
NUMBER OF SHARES
Options outstanding, beginning balance	4,745,200
Granted	656,200
Exercised	(780,700)
Cancelled	(84,000)
Options outstanding, ending balance	4,536,700
Vested and expected to vest, end of period	4,414,300
Exercisable, end of period	2,335,800
PER SHARE EXERCISE PRICE
Options outstanding, beginning balance	$ 41.11	[1]
Granted	$ 59.15	[1]
Exercised	$ 37.21	[1]
Cancelled	$ 48.46	[1]
Options outstanding, ending balance	$ 44.25	[1]
Vested and expected to vest, end of period	$ 43.95	[1]
Exercisable, end of period	$ 39.42	[1]
REMAINING CONTRACTUAL LIFE IN YEARS
Options outstanding, ending balance	5 years 10 months 24 days	[1]
Vested and expected to vest, end of period	5 years 9 months 26 days	[1]
Exercisable, end of period	3 years 10 months 24 days	[1]
AGGREGATE INTRINSIC VALUE
Options outstanding, ending balance	$ 107.8
Vested and expected to vest, end of period	106.2
Exercisable, end of period	$ 66.8

[1] Weighted Average