Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended		12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Options
Options, Beginning Balance	5,078,297
Options, Granted	131,816	1,496,861
Options, Forfeited	(795,391)
Options, Exercised	(1,227,543)
Options, Ending Balance	3,187,179		5,078,297
Options, Vested and expected to vest	2,675,453
Options, Exercisable	1,069,786
Weighted Average Exercise Price
Weighted-Average Exercise Price, Beginning Balance	$ 19.66
Weighted-Average Exercise Price, Granted	22.54
Weighted-Average Exercise Price, Forfeited	26.39
Weighted-Average Exercise Price, Exercised	9.63
Weighted-Average Exercise Price, Ending Balance	21.96		$ 19.66
Weighted-Average Exercise Price, Vested and expected to vest	21.11
Weighted-Average Exercise Price, Exercisable	$ 16.61
Aggregate Intrinsic Value/Weighted Average Exercise Term
Aggregate Intrinsic Value	$ 67,059		$ 41,107
Aggregate Intrinsic Value, Vested and expected to vest	58,572
Aggregate Intrinsic Value, Exercisable	$ 28,246
Weighted-Average Exercise Term, Outstanding Balance	7 years 10 months 6 days		8 years 2 months 16 days
Weighted-Average Exercise Term, Vested and expected to vest	7 years 10 months 6 days
Weighted-Average Exercise Term, Exercisable	6 years 9 months 15 days