Organization and Basis of Presentation - Additional Information (Detail) - USD ($)			3 Months Ended	9 Months Ended
	Aug. 04, 2016	Aug. 03, 2016	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
Organization And Basis Of Presentation [Line Items]
Month and year of incorporation				2007-01
Accumulated deficit			$ (57,281,800)	$ (57,281,800)	$ (48,060,612)
Common stock, shares issued			12,350,360	12,350,360	7,201,774
Repayment of principal and accrued interest				$ 4,500,000
Square 1 Bank [Member] | Loan and security agreement [Member]
Organization And Basis Of Presentation [Line Items]
Repayment of principal and accrued interest	$ 4,500,000
July 2016 Financing and August 2016 Financing [Member]
Organization And Basis Of Presentation [Line Items]
Common stock, shares issued		5,048,632	5,048,632	5,048,632
Aggregate gross proceeds from sale of common stock and warrants		$ 14,500,000	$ 14,500,000
Aggregate net proceeds from sale of common stock and warrants		$ 13,200,000