Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, shares in Millions		3 Months Ended	9 Months Ended
	Mar. 16, 2016	Sep. 30, 2016	Sep. 30, 2016	Dec. 31, 2015
February 2015 Warrants
Class Of Warrant Or Right [Line Items]
Warrants to purchase shares of common stock		8.3	8.3	8.3
Warrant exercise price		$ 3.62	$ 3.62	$ 10.86
February 2015 Warrants | Warrants
Class Of Warrant Or Right [Line Items]
Change in fair value of common stock warrants		$ 500,000	$ 1,200,000
March 2011 Warrants
Class Of Warrant Or Right [Line Items]
Warrants to purchase shares of common stock				3.8
Warrant exercise price				$ 2.46
Number of outstanding warrants that expired	3.8
March 2011 Warrants | Warrants
Class Of Warrant Or Right [Line Items]
Change in fair value of common stock warrants	$ 38,000