Common Stock - Summary of Fair Value of Warrants Issued (Detail) |
6 Months Ended | |
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Jun. 30, 2015 |
Jun. 30, 2014 |
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| Warrant issued in October 2010 [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Risk-free interest rates | 0.28% | 0.22% |
| Expected dividend yield | 0.00% | 0.00% |
| Expected life | 3 months 22 days | 1 year 3 months 18 days |
| Expected volatility | 61.36% | 93.00% |
| Series A and Series B Warrants issued in July 2014 Financing [Member] | ||
| Share-based Compensation Arrangement by Share-based Payment Award [Line Items] | ||
| Risk-free interest rates | 1.32% | |
| Expected dividend yield | 0.00% | |
| Expected life | 4 years 4 days | |
| Expected volatility | 66.18% | |
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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). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Measure of dispersion, in percentage terms (for instance, the standard deviation or variance), for a given stock price. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Risk-free interest rate assumption used in valuing an instrument. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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