Stock Plans - Summary of Option Activity under Plans and Related Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Stock Options Outstanding, Beginning balance	1,949,089
Number of Stock Options Outstanding, Granted	48,260
Number of Stock Options Outstanding, Exercised or released	(19,474)
Number of Stock Options Outstanding, Cancelled or forfeited	(41,422)
Number of Stock Options Outstanding, Ending balance	1,936,453	1,949,089
Number of Shares, Vested and expected to vest	1,729,309
Number of Shares, Exercisable	784,409
Weighted Average Exercise Price of Stock Options Outstanding	$ 39.62	$ 39.27
Weighted Average Exercise Price, Granted	53.59
Weighted Average Exercise Price, Exercised or released	30.29
Weighted Average Exercise Price, Cancelled or forfeited	43.68
Weighted-Average Exercise Price, Vested and expected to vest	38.72
Weighted Average Exercise Price, Exercisable	$ 32.48
Weighted Average Remaining Contractual Term (in years)	7 years 10 months 10 days	8 years 1 month 2 days
Weighted Average Remaining Contractual Term (in years), Vested and expected to vest	7 years 9 months 11 days
Weighted Average Remaining Contractual Term (in years), Exercisable	6 years 11 months 9 days
Aggregate Intrinsic Value	$ 25,732	$ 47,480
Aggregate Intrinsic Value, Vested and expected to vest	24,226
Aggregate Intrinsic Value, Exercisable	$ 14,863