Share-Based Payments - Summary of Stock Option Activity and Related Information (Detail) (USD $)	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Number of Shares
Outstanding at beginning of period	1,438,528
Granted	566,556
Exercised	(54,371)
Cancelled or forfeited	(17,555)
Outstanding at end of period	1,933,158
Exercisable at end of period	645,757
Vested and expected to vest at end of period	1,593,293	[1]
Weighted-Average Exercise Price
Outstanding at beginning of period	$ 4.93
Granted	$ 10.78
Exercised	$ 0.82
Cancelled or forfeited	$ 6.83
Outstanding at end of period	$ 6.74
Exercisable at end of period	$ 3.91
Vested and expected to vest at end of period	$ 7.19	[1]
Remaining Contractual Life (in years)
Outstanding at beginning of period	8 years 3 months 7 days		7 years 10 months 10 days
Exercisable at end of period	7 years 4 months 6 days
Vested and expected to vest at end of period	8 years 5 months 12 days	[1]

[1] Represents the number of vested options, plus the number of unvested options expected to vest.