Stock-based compensation - Summary of Stock Option Activity Under Plan (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Shares
Outstanding at beginning of period | shares	3,532
Granted | shares	1,047
Exercised | shares	(377)
Canceled or forfeited | shares	(467)
Outstanding at end of period | shares	3,735
Exercisable at end of period | shares	1,926
Vested and expected to vest at end of period | shares	3,735
Weighted-average exercise price per share
Outstanding at beginning of period | $ / shares	$ 48.74
Granted | $ / shares	52.09
Exercised | $ / shares	16.30
Canceled or forfeited | $ / shares	55.04
Outstanding at end of period | $ / shares	52.17
Exercisable at end of period | $ / shares	39.23
Vested and expected to vest at end of period | $ / shares	$ 52.17
Outstanding at December 31, 2016	7 years 6 months
Exercisable at December 31, 2016	6 years 6 months
Vested and expected to vest at December 31, 2016	7 years 6 months
Aggregate intrinsic value
Outstanding at end of period | $	$ 93,081	[1]
Exercisable at end of period | $	70,991	[1]
Vested and expected to vest at end of period | $	$ 93,081	[1]

[1] The aggregate intrinsic value is calculated as the difference between the exercise price of the underlying options and the estimated fair value of the common stock for the options that were in the money at December 31, 2016.