Stock Option Plans - Summary of Option Activity for Employees and Non-Employees (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Beginning Balance	1,419,436
Number of Options, Granted	348,908
Number of Options, Ending Balance	1,768,344	1,419,436
Number of Options, Exercisable	1,157,983
Weighted Averaged Exercise Price, Beginning Balance	$ 1.56
Weighted Averaged Exercise Price, Granted	1.72
Weighted Averaged Exercise Price, Ending Balance	1.59	$ 1.56
Weighted Averaged Exercise Price, Exercisable	$ 1.33
Weighted Average Remaining Contractual Life (Years), Outstanding	2 years 11 months 27 days	2 years 9 months 11 days
Weighted Average Remaining Contractual Life (Years), Granted	4 years 10 months 6 days
Weighted Average Remaining Contractual Life (Years), Exercisable	2 years 5 months 5 days
Aggregate Intrinsic Options Value, Beginning Balance	$ 1,220,338
Aggregate Intrinsic Options Value, Ending Balance	466,050	$ 1,220,338
Aggregate Intrinsic Options Value, Exercisable	$ 465,309
Option Activity for Non-Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Beginning Balance	8,333
Number of Options, Ending Balance	8,333	8,333
Number of Options, Exercisable	2,777
Weighted Averaged Exercise Price, Beginning Balance	$ 2.70
Weighted Averaged Exercise Price, Ending Balance	2.70	$ 2.70
Weighted Averaged Exercise Price, Exercisable	$ 2.70
Weighted Average Remaining Contractual Life (Years), Outstanding	4 years 6 months 29 days	4 years 9 months 29 days
Weighted Average Remaining Contractual Life (Years), Exercisable	4 years 6 months 29 days