Stock Warrants (Additional Information) (Detail) (USD $)	12 Months Ended	0 Months Ended
	Dec. 31, 2014	Aug. 05, 2013	Dec. 31, 2013	Dec. 31, 2012
Class of Warrant or Right [Line Items]
Weighted average term of warrants	3 years 7 months 6 days
Weighted average exercise price of warrants per share	$ 2.28
Class Of Warrant Or Right Outstanding	5,236,660		7,147,775	656,641
Warrants 1
Class of Warrant or Right [Line Items]
Class Of Warrant Or Right Outstanding		206,420
Warrants 2
Class of Warrant or Right [Line Items]
Class Of Warrant Or Right Outstanding		38,168
Minimum
Class of Warrant or Right [Line Items]
Outstanding Warrants Expiration Date	May 21, 2015
Minimum | Warrants 1
Class of Warrant or Right [Line Items]
Weighted average exercise price of warrants per share		$ 2.25
Minimum | Warrants 2
Class of Warrant or Right [Line Items]
Weighted average exercise price of warrants per share		$ 2.25
Maximum
Class of Warrant or Right [Line Items]
Outstanding Warrants Expiration Date	Aug. 05, 2018
Maximum | Warrants 1
Class of Warrant or Right [Line Items]
Weighted average exercise price of warrants per share		$ 4.72
Maximum | Warrants 2
Class of Warrant or Right [Line Items]
Weighted average exercise price of warrants per share		$ 5.24