Liquidity, Financial Condition and Management's Plans - Additional Information (Detail)								3 Months Ended	12 Months Ended
	Jan. 08, 2016 USD ($)	Oct. 15, 2015 USD ($)	Oct. 12, 2015 USD ($) closing	Jul. 24, 2015 USD ($)	Mar. 06, 2015 USD ($)	Mar. 05, 2015 USD ($)	Nov. 18, 2014 USD ($) $ / shares shares	Sep. 30, 2015 USD ($) shares	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Liquidity And Managements Plans [Line Items]
Net loss									$ (15,908,546)	$ (13,237,616)
Accumulated deficit									86,246,673	70,338,127
Positive (deficit) in working capital									3,200,000
Net cash used in operating activities									10,299,330	4,484,362
Net proceeds after deducting underwriting discounts and commissions and IPO related expenses									0	10,727,475
Proceeds from exercise of stock options									293,573	0
Value of common stock shares issued									293,573	9,846,552
Proceeds from issuance of Series A Convertible Preferred									4,230,150	0
Expenses related stock issuance									575,181	2,117,217
Series A convertible preferred stock [Member] | Sabby Management, LLC [Member]
Liquidity And Managements Plans [Line Items]
Maximum commitment under stock purchase agreement			$ 10,000,000
Number of closings | closing			2
Proceeds from issuance of Series A Convertible Preferred		$ 4,100,000
Expenses related stock issuance		$ 400,000
Series A convertible preferred stock [Member] | Sabby Management, LLC [Member] | Subsequent event [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from issuance of Series A Convertible Preferred	$ 5,000,000
Expenses related stock issuance	$ 500,000
Aspire Capital Fund, LLC [Member]
Liquidity And Managements Plans [Line Items]
Number of shares issued | shares								506,585
Maximum commitment under stock purchase agreement				$ 10,000,000.0
Purchase agreement term				24 months
Value of common stock shares issued								$ 1,400,000
Series A Warrants [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from exercise of warrants to purchase of common stock					$ 200,000				156,000	0
Value of common stock shares issued									156,000
Series B Warrants [Member]
Liquidity And Managements Plans [Line Items]
Positive (deficit) in working capital									4,100,000
Proceeds from exercise of warrants to purchase of common stock						$ 3,800,000			3,720,713	$ 0
Value of common stock shares issued									$ 3,720,713
Private Placement Series B Warrants [Member]
Liquidity And Managements Plans [Line Items]
Proceeds from exercise of warrants to purchase of common stock						$ 3,800,000
IPO [Member] | Common Stock [Member]
Liquidity And Managements Plans [Line Items]
Capital Stock, Number of Shares Per Unit | shares							1
IPO [Member] | Series A Warrants [Member]
Liquidity And Managements Plans [Line Items]
Capital Stock, Number of Shares Per Unit | shares							1
IPO [Member] | Series B Warrants [Member]
Liquidity And Managements Plans [Line Items]
Capital Stock, Number of Shares Per Unit | shares							1
IPO [Member] | Units [Member]
Liquidity And Managements Plans [Line Items]
Number of shares issued | shares							1,650,000
Offering price per unit | $ / shares							$ 6.50
Net proceeds after deducting underwriting discounts and commissions and IPO related expenses							$ 8,000,000