Warrant Liability - Summary of Changes in Fair Value of Warrant Liability (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Class of Warrant or Right [Line Items]
Fair value of warrant liability, beginning balance	$ 770,964		$ 770,964
Exercised	(2,403,273)
Cancelled	(1,786,170)
Change in fair value of warrant liability	(4,250,308)	$ 427,589	1,596,554	$ 1,068,626
Fair value of warrant liability, ending balance	651,902		651,902
Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Fair value of warrant liability, ending balance	115,000		115,000
Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Fair value of warrant liability, ending balance	482,000		482,000
December 2011 Financing [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Fair value of warrant liability, beginning balance	770,964
Exercised	(838,485)
Change in fair value of warrant liability	122,466
Fair value of warrant liability, ending balance	54,945		54,945
March 2016 Financing [Member] | Series A Warrants [Member]
Class of Warrant or Right [Line Items]
Exercised	(1,564,788)
Change in fair value of warrant liability	1,679,706
Fair value of warrant liability, ending balance	114,918		114,918
March 2016 Financing [Member] | Series B Warrants [Member]
Class of Warrant or Right [Line Items]
Cancelled	(1,786,170)
Change in fair value of warrant liability	2,268,209
Fair value of warrant liability, ending balance	$ 482,039		$ 482,039