Option Activity Under Plan (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share Based Compensation Plans [Line Items]
Exercised		(525,000)
Employee Stock Option [Member]
Share Based Compensation Plans [Line Items]
Outstanding	5,427,778	6,032,188	3,482,188
Granted	349,000	325,000	2,550,000
Exercised	0	(525,000)	0
Forfeited/expired	(25,000)	(404,410)	0
Outstanding	5,751,778	5,427,778	6,032,188	3,482,188
Vested and expected to vest	5,665,871	5,427,778	6,032,188
Exercisable	5,078,611	4,734,861	4,848,298
Weighted - Average Exercise Price, Outstanding	$ 1.03	$ 0.90	$ 1.22
Weighted - Average Exercise Price, Granted	1.46	2.57	0.48
Weighted - Average Exercise Price, Exercised	0	0.83	0
Weighted - Average Exercise Price, Forfeited/expired	2.71	0.68	0
Weighted - Average Exercise Price, Outstanding	1.05	1.03	0.90	$ 1.22
Weighted - Average Exercise Price, Vested and expected to vest	1.04	1.03	0.90
Weighted - Average Exercise Price, Exercisable	$ 1.00	$ 0.99	$ 1.0535
Weighted Average Remaining Contractual Term (In years), Outstanding	5 years 3 months 18 days	6 years	6 years 9 months 18 days	5 years 9 months 18 days
Weighted Average Remaining Contractual Term (In years), Granted	9 years 3 months 18 days	9 years 4 months 24 days	9 years 7 months 6 days
Weighted Average Remaining Contractual Term (In years), Vested and expected to vest	5 years 2 months 12 days	6 years	6 years 9 months 18 days
Weighted Average Remaining Contractual Term (In years), Exercisable	4 years 10 months 24 days	5 years 7 months 6 days	6 years 2 months 12 days
Aggregate Intrinsic Value, Outstanding	$ 8,829,412	$ 18,671,745	$ 5,339
Aggregate Intrinsic Value, Outstanding	1,972,395	8,829,412	18,671,745	$ 5,339
Aggregate Intrinsic Value, Vested and expected to vest	1,971,858	8,829,412	18,671,745
Aggregate Intrinsic Value, Exercisable	$ 1,838,928	$ 7,930,757	$ 14,824,475