Schedule of Weighted-average Number of Shares Used in Calculation of Basic and Diluted Earnings (Loss) Per Share (Details) - shares	3 Months Ended	9 Months Ended
Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2021	Apr. 30, 2020
Earnings Per Share [Abstract]
Basic weighted-average number of shares	25,530,000	26,371,000	25,475,000	26,323,000
Effect of dilutive securities: Stock options	295,000		101,000
Effect of dilutive securities: Non-vested restricted Class B common stock	311,000	135,000	327,000
Diluted weighted-average number of shares	26,136,000	26,506,000	25,903,000	26,323,000

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Number of additional shares included in diluted EPS for potentially dilutive effect of nonvested equity-based payment award containing forfeitable rights to dividends or dividend equivalents, whether paid or unpaid.

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Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of share based payment arrangements using the treasury stock method.

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The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

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Number of [basic] shares or units, after adjustment for contingently issuable shares or units and other shares or units not deemed outstanding, determined by relating the portion of time within a reporting period that common shares or units have been outstanding to the total time in that period.

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