Assumptions used in Estimating Fair Value of Warrant Derivative Liability (Detail) - $ / shares		9 Months Ended	12 Months Ended
Sep. 15, 2016	Feb. 28, 2018	May 31, 2017
Derivative [Line Items]
Fair value of underlying stock	$ 0.78	$ 0.79	$ 0.60
Risk free rate	1.20%	2.58%	1.71%
Expected term (in years)	5 years	3 years 6 months 14 days	4 years 3 months 15 days
Stock price volatility	106.00%	75.00%	94.00%
Expected dividend yield	0.00%	0.00%	0.00%
Probability of Fundamental Transaction	50.00%	50.00%	50.00%
Probability of holder requesting cash payment	50.00%	50.00%	50.00%

Fair Value Inputs, Probability of Fundamental Transaction

No definition available.

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- Definition

Fair Value Inputs, Probability of Holder Requesting Cash Payment

+ References

No definition available.

+ Details

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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.

+ References

No definition available.

+ Details

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- Definition

Agreed upon price for the exchange of the underlying asset.

+ 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 (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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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).

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+ 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.

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+ Details

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- Definition

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

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+ Details

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- Definition

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

+ References

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