Change in Value of Warrant and Derivative Liability Unobservable Inputs Financial Instrument Reconciliation (Detail) (USD $)					3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 Level 2	Dec. 31, 2013 Level 2	Mar. 31, 2014 Derivative Liability	Mar. 31, 2014 Warrant Liability
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair Value	$ 3,680,000	$ 6,602,000
Change in fair value recorded as a loss from change in fair value of financial liability					(2,046,000)	(688,000)
Adjustment to fair value of derivative liability related to early conversion of notes					(188,000)
Fair value	3,680,000	6,602,000
Debt Instrument, Fair Value Disclosure			$ 123,000,000	$ 117,700,000