Combined Stock Option Activity (Detail) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / shares shares
Number of shares
Beginning Balance | shares	6,563
Granted | shares	2,691
Exercised | shares	(1,275)
Forfeited/Cancelled | shares	(516)
Ending Balance | shares	7,463
Vested and expected to vest as December 31, 2016 | shares	6,154
Exercisable as of December 31, 2016 | shares	2,696
Weighted Average Exercise Price
Beginning Balance | $ / shares	$ 16.01
Granted | $ / shares	25.72
Exercised | $ / shares	14.41
Forfeited/Cancelled | $ / shares	20.85
Ending Balance | $ / shares	19.45
Vested and expected to vest as December 31, 2016 | $ / shares	18.99
Exercisable as of December 31, 2016 | $ / shares	$ 14.21
Weighted average remaining contractual term
Vested and expected to vest as December 31, 2016	7 years 3 months 18 days
Exercisable as of December 31, 2016	5 years 8 months 12 days
Aggregate Intrinsic Value
Vested and expected to vest as December 31, 2016 | $	$ 104,655
Exercisable as of December 31, 2016 | $	$ 58,741