Subsequent Event - Additional Information (Detail) (USD $) In Millions, except Share data, unless otherwise specified	0 Months Ended
	Nov. 03, 2014	Jul. 22, 2014	Feb. 10, 2014
Subsequent Event [Line Items]
Common stock shares issued		6,250,000	1,945,525
Common stock issued, price per share		$ 1.92	$ 2.57
Proceeds from equity offering, gross		$ 12.0	$ 5.0
Term of agreement	3 years
Subsequent Event
Subsequent Event [Line Items]
Common stock shares issued	14,162,873
Common stock issued, price per share	$ 2.39
Warrants to purchase common stock	9,205,862
Class of Warrant or Right, Exercise Price of Warrants or Rights	$ 4.00
Proceeds from equity offering, gross	$ 35.0
Warrant exercisable period after closing of private placement	6 months
Term of agreement	3 years