Stockholders' Equity Common Stock - Summary of Stock Option Activity (Detail) - USD ($) $ / shares in Units, $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2016	Dec. 31, 2015
Equity [Abstract]
Number of shares, Beginning Balance	5,026,246
Number of shares, Granted	1,418,625
Number of shares, Exercised	(777,138)
Number of shares, Forfeited	(55,344)
Number of shares, Ending Balance	5,612,389	5,026,246
Number of shares, Options exercisable	1,793,436
Number of shares, Options vested and expected to vest	5,491,857
Weighted Average Exercise Price, Beginning Balance	$ 8.01
Weighted Average Exercise Price, Granted	28.05
Weighted Average Exercise Price, Exercised	1.21
Weighted Average Exercise Price, Forfeited	13.48
Weighted Average Exercise Price, Ending Balance	13.96	$ 8.01
Weighted Average Exercise Price, Options exercisable	6.00
Weighted Average Exercise Price, Options vested and expected to vest	$ 13.85
Weighted Average Remaining Contractual Term, Outstanding	8 years 4 months 28 days	8 years 8 months 12 days
Weighted Average Remaining Contractual Term, Options exercisable	7 years 6 months 7 days
Weighted Average Remaining Contractual Term, Options vested and expected to vest	8 years 4 months 24 days
Aggregate Intrinsic Value	$ 88,441	$ 136,945
Aggregate Intrinsic Value, Options exercisable	41,438
Aggregate Intrinsic Value, Options vested and expected to vest	$ 87,103