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Marketable Securities (Details) - Schedule of Available-for-sale Securities - USD ($)
$ in Thousands
12 Months Ended
Apr. 30, 2020
Apr. 30, 2019
Schedule of Available-for-sale Securities [Abstract]    
Cost $ 10,081 $ 8,152
Gross Unrealized Gains 495 71
Gross Unrealized Losses (6) (24)
Fair Market Value $ 10,570 $ 8,199