Preferred and Common Stock - Schedule of Stock Options Activity (Details) - $ / shares	12 Months Ended
Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Number of option shares
Ending balance (in shares)	43,189
Stock Options
Number of option shares
Beginning balance (in shares)	109,827	181,673	222,050
Exercised (in shares)	(66,638)	(71,546)	(40,377)
Forfeited (in shares)		(300)
Ending balance (in shares)	43,189	109,827	181,673
Weighted average option exercise price
Beginning balance (in Dollars per share)	$ 44.39	$ 39.48	$ 38.51
Exercised (in Dollars per share)	44.39	32.02	34.11
Forfeited (in Dollars per share)		25.26
Ending balance (in Dollars per share)	$ 44.39	$ 44.39	$ 39.48

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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- Definition

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

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- Definition

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

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

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