Combined Stock Option Activity (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
Dec. 31, 2014
Number of shares
Beginning Balance	5,996
Granted	1,361
Exercised	(954)
Forfeited/Cancelled	(303)
Ending Balance	6,100
Vested and expected to vest as December 31, 2014	5,103
Exercisable as of December 31, 2014	2,558
Weighted Average Exercise Price
Beginning Balance	$ 10.48
Granted	$ 20.05
Exercised	$ 7.17
Forfeited/Cancelled	$ 13.49
Ending Balance	$ 12.99
Vested and expected to vest as December 31, 2014	$ 12.67
Exercisable as of December 31, 2014	$ 10.03
Weighted average remaining contractual term
Vested and expected to vest as December 31, 2014	6 years 9 months 18 days
Exercisable as of December 31, 2014	5 years 1 month 6 days
Aggregate Intrinsic Value
Vested and expected to vest as December 31, 2014	$ 41,449
Exercisable as of December 31, 2014	$ 27,477

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