Operating Matters and Liquidity - Additional Information (Detail) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 29, 2016	Dec. 23, 2014	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Line of Credit Facility [Line Items]
Net Income Loss			$ (2,087,201)	$ (2,166,786)	$ (3,604,936)	$ (4,009,981)	$ 7,900,000	$ 6,300,000
Accumulated deficit			$ (132,593,261)		$ (132,593,261)		$ (128,988,325)
Venture Loan [Member]
Line of Credit Facility [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.1003
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		2,492,523
Debt Instrument, Payment Terms		The loan is to be repaid in forty-five (45) monthly payments consisting of fifteen (15) monthly payments of only interest followed by thirty (30) equal monthly payments of principal and interest. In addition, at the end of the repayment term (or at early termination of the loan) a final payment equal to 4.5% of the loan will be due and payable
Proceeds from Issuance of Long-term Debt		$ 5,000,000
Debt Instrument, Interest Rate, Stated Percentage		9.00%	9.00%		9.00%
Warrants Expire Term		10 years
Venture Loan [Member] | Horizon Technology Finance Corporation [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Description of Variable Rate Basis		The loan bears interest at a floating rate equal to the One Month LIBOR Rate (with a floor of 0.50%) plus 8.50%. In the event that the One Month LIBOR Rate, as reported in the Wall Street Journal, exceeds 0.50%, the interest rate will be adjusted by an amount equal to the difference between such rates at the end of that particular month
December 2014 Private Placement [Member]
Line of Credit Facility [Line Items]
Sale of Stock, Number of Shares Issued in Transaction		50,099,700
Sale of Stock, Price Per Share		$ 0.1003
Sale of Stock, Consideration Received on Transaction		$ 5,025,000
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.1003		$ 0.1003
2014 warrants [Member]
Line of Credit Facility [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 0.1003
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		50,099,700
Warrants Expire Term		7 years
Common Stock [Member]
Line of Credit Facility [Line Items]
Net Income Loss					$ 0
Common Stock [Member] | Private Placement [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Sale of Stock, Number of Shares Issued in Transaction	56,262,571
Sale of Stock, Price Per Share	$ 0.0994
Sale of Stock, Consideration Received on Transaction	$ 5,600,000