Loan Payable - Assumptions Used for Black-Scholes Option Pricing Model (Detail) (Silicon Valley Bank Loan Agreement Warrant [Member])	9 Months Ended
Sep. 30, 2013
Silicon Valley Bank Loan Agreement Warrant [Member]
Class of Warrant or Right [Line Items]
Expected life (years)	10 years
Risk-free interest rate	1.90%
Expected volatility	88.10%
Expected dividend yield	0.00%

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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

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

+ References

+ Details

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- Definition

Weighted average expected volatility of stock price.

+ References

+ Details

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