Note 4 - Stock-based Compensation (Details Textual)	3 Months Ended
Jul. 27, 2019 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period	400
Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price \| $ / shares	$ 17.59
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number, Ending Balance	322,045
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price, Ending Balance \| $ / shares	$ 11.13
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant	2,811,613

The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
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- Definition

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

+ References

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

+ References

No definition available.

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

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