Liquidity, Financial Condition and Management's Plans - Additional Information (Detail)					3 Months Ended
	Jan. 08, 2016 USD ($)	Oct. 15, 2015 USD ($)	Oct. 12, 2015 USD ($) closing	Jul. 24, 2015 USD ($)	Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Liquidity And Managements Plans [Line Items]
Net loss					$ (3,189,000)	$ (11,651,000)
Accumulated deficit					(89,436,000)		$ (86,247,000)
Positive (deficit) in working capital					5,000,000
Net cash used in operating activities					(3,984,000)	(1,809,000)
Proceeds from sale of Series A preferred convertible stock					5,071,000	0
Expenses related stock issuance					0	530,000
Series A Convertible Preferred Stock [Member]
Liquidity And Managements Plans [Line Items]
Expenses related stock issuance					$ 71,000	$ 0
Sabby Management, LLC [Member] | Series A Convertible Preferred Stock [Member]
Liquidity And Managements Plans [Line Items]
Number of closings | closing			2
Maximum commitment under stock purchase agreement			$ 10,000,000
Proceeds from sale of Series A preferred convertible stock	$ 5,000,000	$ 4,100,000
Expenses related stock issuance	$ 500,000	$ 400,000
Aspire Capital Fund, LLC [Member]
Liquidity And Managements Plans [Line Items]
Maximum commitment under stock purchase agreement				$ 10,000,000.0
Agreement term				24 months