Fair Value Assumptions Used in Accounting for Call Options (Details) - Call Option - $ / shares	9 Months Ended	12 Months Ended
Apr. 30, 2018	Jul. 31, 2017
Risk-free interest rate	2.10%	1.34%
Estimated volatility	133.40%	143.90%
Remaining Term	1 year 8 months 16 days	2 years 5 months 20 days
Stock price at valuation date	$ 2.95	$ 5.05

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
-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

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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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- Definition

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

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- Definition

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

+ References

No definition available.

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