Summary of Options (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
NUMBER OF SHARES
Options outstanding, beginning balance | shares	4,090,900
Granted | shares	883,600
Exercised | shares	(1,288,800)
Cancelled | shares	(197,400)
Options outstanding, ending balance | shares	3,488,300
Vested and expected to vest, end of period | shares	3,401,100
Exercisable, end of period | shares	1,792,800
PER SHARE EXERCISE PRICE
Options outstanding, beginning balance | $ / shares	$ 55.32	[1]
Granted | $ / shares	65.56	[1]
Exercised | $ / shares	47.47	[1]
Cancelled | $ / shares	66.60	[1]
Options outstanding, ending balance | $ / shares	60.18	[1]
Vested and expected to vest, end of period | $ / shares	60.01	[1]
Exercisable, end of period | $ / shares	$ 53.71	[1]
REMAINING CONTRACTUAL LIFE IN YEARS
Options outstanding, ending balance	6 years 2 months 19 days	[1]
Vested and expected to vest, end of period	6 years 1 month 24 days	[1]
Exercisable, end of period	4 years 3 months 10 days	[1]
AGGREGATE INTRINSIC VALUE
Options outstanding, ending balance | $	$ 66.0
Vested and expected to vest, end of period | $	64.9
Exercisable, end of period | $	$ 45.5

[1] Weighted Average