Operating Matters and Liquidity - Additional Information (Detail) - USD ($)	1 Months Ended				3 Months Ended		12 Months Ended
	Aug. 31, 2016	Aug. 25, 2016	Jul. 29, 2016	Dec. 23, 2014	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016	Dec. 31, 2015	Apr. 17, 2017	Aug. 09, 2013
Line of Credit Facility [Line Items]
Net Income Loss					$ (2,529,710)	$ (1,517,736)	$ 7,400,000	$ 7,900,000
Accumulated deficit					(138,932,134)		$ (136,402,424)
Warrants Expire Term				10 years
Working Capital Deficit					5,500,000
Cash					791,000
Accounts Payable and Accrued Liabilities					1,100,000
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights									$ 0.10438
Subordinated Convertible Promissory Notes [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Face Amount									$ 1,000,000
Horizon Technology Finance Corporation [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Description of Variable Rate Basis				The loan bore 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, exceeded 0.50%, the interest rate would have been adjusted by an amount equal to the difference between such rates at the end of that particular month.
Debt Instrument, Face Amount					$ 3,600,000
Lender Warrant 2016 [Member]
Line of Credit Facility [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 0.0994
Class of Warrant or Right, Number of Securities Called by Warrants or Rights					5,169,577
Warrants Expire Term					10 years		10 years
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, Description of Variable Rate Basis					The loan bore interest at a floating rate equal to the One Month LIBOR Rate (with a floor of 0.50%) plus 8.50%.
Debt Instrument, Payment Terms					The loan was 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 (the “Payment Terms”). 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 would have been due and payable.
Proceeds from Issuance of Long-term Debt				$ 5,000,000
Warrants Expire Term					10 years
Debt Restructuring 2016 [Member]
Line of Credit Facility [Line Items]
Debt Instrument, Description of Variable Rate Basis		one month LIBOR Rate exceeds 0.50%
Debt Instrument, Interest Rate, Stated Percentage		11.00%			11.48%
Debt Principal Amount Reduced Percentage		33.00%			33.00%					33.00%
Payments for Other Fees	$ 25,000	$ 25,000
Legal Fees	$ 5,000	$ 5,000
Debt Instrument, Increase (Decrease) for Period, Description		the final payment was increased from 4.5% of the loan, or $225,000, to 6.5% of the loan, or $325,000			the final payment was increased from 4.5% of the loan, or $225,000, to 6.5% of the loan, or $325,000
Private Placement [Member]
Line of Credit Facility [Line Items]
Class of Warrant or Right, Exercise Price of Warrants or Rights					$ 0.1003
Warrants [Member]
Line of Credit Facility [Line Items]
Sale of Stock, Price Per Share			$ 0.0994
Sale of Stock, Consideration Received on Transaction			$ 56,262,571
Common Stock [Member]
Line of Credit Facility [Line Items]
Net Income Loss					$ 0
Common Stock [Member] | Private Placement [Member]
Line of Credit Facility [Line Items]
Sale of Stock, Consideration Received on Transaction			$ 5,600,000
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 0.0994
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			56,262,571