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Marketable Securities (Details) - Schedule of Unrealized Gain (Loss) on Investments - Fixed Income Securities [Member] - USD ($)
$ in Thousands
Apr. 30, 2020
Apr. 30, 2019
Marketable Securities (Details) - Schedule of Unrealized Gain (Loss) on Investments [Line Items]    
Fair Value, Less than 12 months $ 380 $ 995
Unrealized Losses, Less than 12 months (6) (4)
Fair Value, Morethan 12 months 0 3,349
Unrealized Losses, More than 12 months 0 (20)
Fair Value 380 4,344
Unrealized Losses $ (6) $ (24)