Weighted average price of options that were exchanged under contractual agreement.

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Percentage of stock vested for share based compensation arrangement by share based payment award options during the period.

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No definition available.

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The number of shares under options that were exchanged during the reporting period as a result of occurrence of an event specified in contractual agreements pertaining to the stock option plan.

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No definition available.

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The number of share warrants outstanding in connection with the financing arrangement.

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Plan Modification, Future Incremental Compensation Cost

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No definition available.

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Term of Option to Purchase

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No definition available.

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- Definition

Number of shares to purchase common stock option awards during the reporting period.

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No definition available.

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Number of shares to purchase of unregistered common stock option awards during the reporting period.

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No definition available.

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

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No definition available.

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- Definition

Net number of share options (or share units) granted during the period.

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-Publisher FASB
-Name Accounting Standards Codification
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Gross number of share options (or share units) granted during the period.

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No definition available.

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The weighted average grant-date fair value of options granted during the reporting period as calculated by applying the disclosed option pricing methodology.

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-Publisher FASB
-Name Accounting Standards Codification
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An excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

+ References

No definition available.

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- Definition

The excess of the fair value of the modified award over the fair value of the award immediately before the modification.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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- Definition

Purchase price of common stock expressed as a percentage of its fair value.

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No definition available.

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The noncash expense that accounts for the value of stock or unit options distributed to employees as compensation.

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Stock-based Payments - Narrative (Details) - USD ($)					3 Months Ended	12 Months Ended
Stock-based Payments - Narrative (Details) - USD ($)	Apr. 24, 2017	Jul. 21, 2016	Dec. 12, 2013	Feb. 18, 2011	Jul. 31, 2016	Apr. 30, 2018	Apr. 30, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense						$ 1,034,000	$ 2,662,000
Stock options award shares to purchase common stock			16,667
Grants in period, weighted average grant date fair value (in dollars per share)						$ 2.19	$ 1.71
Shares granted (in shares)		1,568,191				455,310	2,420,681
Modification expense (in usd)						$ 56,529
Shares exchange during period (in shares)		1,793,781
Grants in period, weighted average exercise price (in usd per share)		$ 2.10				$ 3.01	$ 1.99
Warrants outstanding (in shares)						2,004,284
Stock-based compensation related to issuance of common stock as compensation for services performed						$ 15,000
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expense						$ 689,000	$ 2,193,000
Stock or unit option plan expense							$ 612,534,000
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchanges, weighted average exercise price (in dollars per share)		4.55
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exchanges, weighted average exercise price (in dollars per share)		$ 6.96
Equity Incentive Plan 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term of awards						10 years
Strike price as percent of market value						100.00%
Equity Incentive Plan 2010 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted, net of forfeitures (in shares)				30,000,000
2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expiration term of awards						10 years
Director Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options award shares to purchase common stock			8,333
Stock option award shares to purchase unregistered common stock			1,667
Vested percent			25.00%
Board of Directors Chairman \| Director Compensation Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Term of option to purchase						5 years
Chief Executive Officer and President
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)							203,043
November 2016 \| Chief Executive Officer and President
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)							209,383
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Modification expense (in usd)		$ 414,756			$ 373,069
Modification expense for future period (in usd)		1,767
Employee Stock Option \| Chief Executive Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Modification expense (in usd)	$ 612,534
Employee Stock Options Forfeited
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Modification expense (in usd)		$ 39,920