Summary of Options (Detail) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
NUMBER OF SHARES
Options outstanding, beginning balance | shares	3,488,300
Granted | shares	641,700
Exercised | shares	(949,900)
Cancelled | shares	(63,600)
Options outstanding, ending balance | shares	3,116,500
Vested and expected to vest, end of period | shares	3,014,300
Exercisable, end of period | shares	1,323,200
PER SHARE EXERCISE PRICE
Options outstanding, beginning balance | $ / shares	$ 60.18	[1]
Granted | $ / shares	76.18	[1]
Exercised | $ / shares	56.68	[1]
Cancelled | $ / shares	69.75	[1]
Options outstanding, ending balance | $ / shares	64.34	[1]
Vested and expected to vest, end of period | $ / shares	64.06	[1]
Exercisable, end of period | $ / shares	$ 56.63	[1]
REMAINING CONTRACTUAL LIFE IN YEARS
Options outstanding, ending balance	6 years 5 months 23 days	[1]
Vested and expected to vest, end of period	6 years 4 months 24 days	[1]
Exercisable, end of period	4 years 1 month 24 days	[1]
AGGREGATE INTRINSIC VALUE
Options outstanding, ending balance | $	$ 68.4
Vested and expected to vest, end of period | $	67.0
Exercisable, end of period | $	$ 39.2

[1] Weighted Average