Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) (USD $)	9 Months Ended	12 Months Ended
Sep. 30, 2013	Dec. 31, 2012
October 2009 offering [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	0.10%	0.25%
Expected life (in years)	1 year 4 days	1 year 9 months 4 days
Dividend yield
Volatility	56.00%	98.00%
Stock price	$ 4.65	$ 4.21
March 2011 offering [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Risk-free interest rate	0.63%	0.72%
Expected life (in years)	2 years 5 months 16 days	3 years 2 months 16 days
Dividend yield
Volatility	87.00%	94.00%
Stock price	$ 4.65	$ 4.21

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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

+ Details

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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

+ Details

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- Definition

Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price.

+ References

+ Details

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- Definition

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

+ References

+ Details

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- Definition

Price of a single share of a number of saleable stocks of a company.

+ References

+ Details

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