Share-Based Payments (Details 1)	12 Months Ended
Apr. 30, 2020 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding at May 1, 2019, number of options \| shares	400,000
Granted, number of options \| shares	193,831
Exercised, number of options \| shares	(62,750)
Cancelled, number of options \| shares	(42,026)
Outstanding at April 30, 2020, number of options \| shares	489,055
Exercisable at April 30, 2020, number of options \| shares	314,750
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Outstanding at May 1, 2019, weighted average exercise price (in dollars per share) \| $ / shares	$ 113.24
Granted, weighted average exercise price (in dollars per share) \| $ / shares	121.93
Exercised, weighted average exercise price (in dollars per share) \| $ / shares	111.66
Cancelled, weighted average exercise price (in dollars per share) \| $ / shares	120.67
Outstanding at April 30, 2020, weighted average exercise price (in dollars per share) \| $ / shares	116.25
Exercisable at April 30, 2020, weighted average exercise price (in dollars per share) \| $ / shares	$ 113.21

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

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No definition available.

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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
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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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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Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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

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