Stockholders' Equity - Outstanding Warrants Valuation Assumption (Detail) - $ / shares |
6 Months Ended | 12 Months Ended |
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Jun. 30, 2018 |
Dec. 31, 2017 |
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| Fair Value Disclosures [Abstract] | ||
| Risk-free interest rate | 2.52% | 1.89% |
| Expected life (in years) | 1 year 7 months 20 days | 2 years 1 month 17 days |
| Dividend yield | 0.00% | 0.00% |
| Volatility | 78.00% | 103.00% |
| Stock price | $ 5.23 | $ 10.02 |
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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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- References No definition available.
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- Definition Price of a single share of a number of saleable stocks of a company. No definition available.
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