Warrant Liability - Assumptions used for Black-Scholes Option Pricing Model1 (Detail) (USD $)	3 Months Ended	6 Months Ended		6 Months Ended	12 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Warrant Agreement 2009 [Member]	Dec. 31, 2012 Warrant Agreement 2009 [Member]
Class of Warrant or Right [Line Items]
Expected life (years)						1 year 9 months 18 days	2 years 3 months 18 days
Risk-free interest rate						0.30%	0.30%
Expected volatility						96.70%	94.50%
Expected dividend yield						0.00%	0.00%
Fair value of warrant liability	$ 8,277,443		$ 8,277,443		$ 9,265,365	$ 42,192	$ 63,340
Change in fair value of warrant liability	$ (757,688)	$ (6,205,957)	$ (569,081)	$ (1,264,780)		$ (21,148)

Fair Value Of Warrant Liability

No definition available.

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- Definition

Amount of expense (income) related to adjustment to fair value of warrant liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 480

-SubTopic 10

-Section 25

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6939902&loc=d3e20148-110875

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- Definition

Expected dividends to be paid to holders of the underlying shares or financial instruments (expressed as a percentage of the share or instrument's price).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

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- Definition

Period the instrument, asset or liability is expected to be outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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- Definition

Risk-free interest rate assumption used in valuing an instrument.

+ References

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- Definition

Weighted average expected volatility of stock price.

+ References

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