Stockholders' Equity - Schedule of Outstanding Common Stock Warrants (Detail) (USD $)	12 Months Ended
	Dec. 31, 2014	Feb. 28, 2014
Class of Warrant or Right [Line Items]
Total Warrants	13,078,920	1,329,731
Ex. Price $ 11.18 [Member]
Class of Warrant or Right [Line Items]
Issue Date	Apr. 26, 2013
Expiration Date	Apr. 26, 2018
Total Warrants	69,321
Ex. Price	$ 11.18
Ex. Price $ 8.50 [Member]
Class of Warrant or Right [Line Items]
Issue Date	Oct. 31, 2013
Expiration Date	Apr. 30, 2019
Total Warrants	685,715
Ex. Price	$ 8.50
Ex. Price $ 7.40 [Member]
Class of Warrant or Right [Line Items]
Issue Date	Feb. 05, 2014
Expiration Date	Feb. 05, 2019
Total Warrants	1,329,731
Ex. Price	$ 7.40
Ex. Price $ 2.45 [Member]
Class of Warrant or Right [Line Items]
Issue Date	Jul. 24, 2014
Expiration Date	Jul. 24, 2019
Total Warrants	6,198,832
Ex. Price	$ 2.45
Ex. Price $ 2.45 [Member]
Class of Warrant or Right [Line Items]
Issue Date	Jul. 24, 2014
Expiration Date	Jan. 24, 2016
Total Warrants	4,795,321
Ex. Price	$ 2.45