Fair Value of Warrants (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Class of Warrant or Right [Line Items]
Warrant liability	$ 3,931,000	$ 20,390,000	[1]
2009 Warrants
Class of Warrant or Right [Line Items]
Warrant liability	0	8,542,000
2010 Warrants
Class of Warrant or Right [Line Items]
Warrant liability	$ 3,931,000	$ 11,848,000

[1] The financial information in this column was derived from audited financial statements included in the Company's 2013 Annual Report on Form 10-K.