Share Based Compensation - Stock Option Activity (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Stockholders Equity Note [Abstract]
Number of Shares Outstanding, Beginning Balance	9,480,497	7,245,485	7,697,892
Number of Shares Granted/Issued	4,029,500	2,984,010	2,596,201
Number of Shares Exercised	(142,493)	(20,000)	(2,124,123)
Number of Shares Cancelled/Forfeited	(2,053,595)	(728,998)	(924,485)
Number of Shares Outstanding, Ending Balance	11,313,909	9,480,497	7,245,485
Number of Shares Exercisable, Ending Balance	7,789,081
Weighted Average Exercise Price Outstanding, Beginning Balance	$ 2.19	$ 2.25	$ 1.89
Weighted Average Exercise Price Granted/Issued	1.14	2.23	2.89
Weighted Average Exercise Price Exercised	1.23	1.54	1.21
Weighted Average Exercise Price Cancelled/Forfeited	2.13	2.92	3.41
Weighted Average Exercise Price Outstanding, Ending Balance	1.84	$ 2.19	$ 2.25
Weighted Average Exercise Price Exercisable, Ending Balance	$ 2.04
Weighted Average Remaining Contractual Term (Years) Outstanding, Ending Balance	7 years
Weighted Average Remaining Contractual Term (Years) Exercisable, Ending Balance	6 years 1 month 6 days
Aggregate Intrinsic Value, Exercised	$ 121,782		$ 3,585,453
Aggregate Intrinsic Value Outstanding, Ending Balance	7,741,133
Aggregate Intrinsic Value Exercisable, Ending Balance	$ 513,003