Option Activity Under Plan (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Share Based Compensation Plans [Line Items]
Exercised	(525,000)
Employee Stock Option [Member]
Share Based Compensation Plans [Line Items]
Outstanding	6,032,188	3,482,188	3,432,188
Granted	325,000	2,550,000	50,000
Exercised	(525,000)	0	0
Forfeited/expired	(404,410)	0	0
Outstanding	5,427,778	6,032,188	3,482,188	3,432,188
Vested and expected	5,427,778	6,032,188	3,482,188
Exercisable	4,734,861	4,848,298	181,771
Weighted - Average Exercise Price, Outstanding	$ 0.90	$ 1.22	$ 1.23
Weighted - Average Exercise Price, Granted	$ 2.57	$ 0.48	$ 0.37
Weighted - Average Exercise Price, Exercised	$ 0.83	$ 0	$ 0
Weighted - Average Exercise Price, Forfeited/expired	$ 0.68	$ 0	$ 0
Weighted - Average Exercise Price, Outstanding	$ 1.03	$ 0.90	$ 1.22	$ 1.23
Weighted - Average Exercise Price, Vested and expected to vest	$ 1.03	$ 0.90	$ 1.22
Weighted - Average Exercise Price, Exercisable	$ 0.99	$ 1.0535	$ 0.32
Weighted Average Remaining Contractual Term (In years), Outstanding	6 years	6 years 9 months 18 days	5 years 9 months 18 days	6 years 9 months 18 days
Weighted Average Remaining Contractual Term (In years), Granted	9 years 4 months 24 days	9 years 7 months 6 days	9 years 6 months
Weighted Average Remaining Contractual Term (In years), Vested and expected to vest	6 years	6 years 9 months 18 days	5 years 9 months 18 days
Weighted Average Remaining Contractual Term (In years), Exercisable	5 years 7 months 6 days	6 years 2 months 12 days	7 years
Aggregate Intrinsic Value, Outstanding	$ 18,671,745	$ 5,339	$ 2,839
Aggregate Intrinsic Value, Outstanding	8,829,412	18,671,745	5,339	2,839
Aggregate Intrinsic Value, Vested and expected to vest	8,829,412	18,671,745	5,339
Aggregate Intrinsic Value, Exercisable	$ 7,930,757	$ 14,824,475	$ 4,130