Stockholders' Equity - Share Based Compensation Stock Options Activity (Detail) - $ / shares	3 Months Ended	9 Months Ended
Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019
Shares
Options outstanding, beginning of year, Shares			267,761	316,160
Exercised during the period, Shares	0	0	(15,000)	(32,899)
Canceled/forfeited during period, Shares			(160,667)
Options outstanding, end of period, Shares	92,094	283,261	92,094	283,261
Weighted average remaining contractual life			5 months 12 days	2 years 5 months 26 days
Options exercisable, end of period, Shares	92,094	283,261	92,094	283,261
Weighted average remaining contractual life			5 months 12 days	2 years 5 months 26 days
Weighted-Average Exercise Price
Options outstanding, beginning of year, Weighted-Average Exercise Price			$ 6.76	$ 6.69
Exercised during period, Weighted-Average Exercise Price			5.79	6.52
Canceled/forfeited during period, Weighted-Average Exercise Price			8.89
Options outstanding, end of period, Weighted-Average Exercise Price	$ 3.22	$ 6.71	3.22	6.71
Options exercisable, end of period, Weighted-Average Exercise Price	$ 3.22	$ 6.71	$ 3.22	$ 6.71

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

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

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Number of options outstanding, including both vested and non-vested options.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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