Stock Option Plans - Summary of Option Activity for Employees and Non-Employees (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2014
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Beginning Balance	1,472,130
Number of Options, Granted	157,306
Number of Options, Ending Balance	1,629,436	1,472,130
Number of Options, Exercisable, Ending Balance	1,077,520
Weighted Averaged Exercise Price, Beginning Balance	$ 1.33
Weighted Averaged Exercise Price, Granted	3.01
Weighted Averaged Exercise Price, Ending Balance	1.49	$ 1.33
Weighted Averaged Exercise Price, Exercisable, Ending Balance	$ 1.14
Weighted Average Remaining Contractual Life (Years), Outstanding	2 years 6 months	3 years 2 months 23 days
Weighted Average Remaining Contractual Life (Years), Granted	4 years 5 months 23 days
Weighted Average Remaining Contractual Life (Years), Exercisable	1 year 11 months 12 days
Aggregate Intrinsic Options Value, Beginning Balance	$ 1,430,231
Aggregate Intrinsic Options Value, Granted	57,000
Aggregate Intrinsic Options Value, Ending Balance	2,620,771	$ 1,430,231
Aggregate Intrinsic Options Value, Exercisable, Ending Balance	$ 2,093,571
Option Activity for Non-Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Options, Beginning Balance	16,666
Number of Options, Exercised	8,333
Number of Options, Ending Balance	8,333	16,666
Number of Options, Exercisable, Ending Balance	8,333
Weighted Averaged Exercise Price, Beginning Balance	$ 1.27
Weighted Averaged Exercise Price, Exercised	1.53
Weighted Averaged Exercise Price, Ending Balance	1.01	$ 1.27
Weighted Averaged Exercise Price, Exercisable, Ending Balance	$ 1.01
Weighted Average Remaining Contractual Life (Years), Outstanding	2 months 9 days	7 months 13 days
Weighted Average Remaining Contractual Life (Years), Exercisable	2 months 9 days
Aggregate Intrinsic Options Value, Beginning Balance	$ 17,166
Aggregate Intrinsic Options Value, Ending Balance	17,166	$ 17,166
Aggregate Intrinsic Options Value, Exercisable, Ending Balance	$ 17,166