Stock Incentive Plan - Summary of Activity Relating to Stock Options (Detail) - USD ($)	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Share-based Compensation Arrangement by Share-based Payment Award, Options Outstanding, Weighted Average Exercise Price, and Additional Disclosures [Abstract]
Number of Shares Outstanding, Beginning Balance	1,077,330
Number of Shares, Granted	721,814
Number of Shares, Cancelled	(62,104)
Number of Shares, Forfeited	(36,157)
Number of Shares, Expired	0
Number of Shares, Exercised	(96,042)
Number of Shares Outstanding, Ending Balance	1,604,871
Number of Shares Exercisable, Ending Balance	759,251	802,921
Weighted Average Exercise Price, Beginning Balance	$ 3.98
Weighted Average Exercise Price, Granted	5.35
Weighted Average Exercise Price, Cancelled	4.83
Weighted Average Exercise Price, Forfeited	5.68
Weighted Average Exercise Price, Expired	0
Weighted Average Exercise Price, Exercised	0.55
Weighted Average Exercise Price, Ending Balance	4.76
Weighted Average Exercise Price Exercisable, Ending Balance	$ 4.21	$ 5.35
Weighted Average Contractual Term, Outstanding	8 years 2 months 5 days
Weighted Average Contractual Term, Exercisable	7 years 3 months 18 days	7 years 1 month 6 days
Aggregate Intrinsic Value, Outstanding	$ 5,211,390
Aggregate Intrinsic Value, Exercisable	$ 3,195,987	$ 3,701,212