Earnings Per Share And Stockholders' Equity (Narrative) (Details) - USD ($)	3 Months Ended	6 Months Ended
Oct. 31, 2020	Oct. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Earnings Per Share And Stockholders' Equity [Abstract]
Options to purchase, common stock outstanding	513,232	465,232	513,232	465,232
Options granted			0	0
Stock option expense	$ 0	$ 0	$ 0	$ 0
Balance of unrecognized compensation expense related to stock options plans	$ 0	$ 0	$ 0	$ 0
Anti-dilutive common stock outstanding excluded from the calculation of diluted earnings per share	314,740	147,706	306,420	241,465

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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Amount of cost to be recognized for option under share-based payment arrangement.

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

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

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Amount of noncash expense for option under share-based payment arrangement.

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