Debt Securities (Details) - Schedule of available-for-sale securities, unrealized loss position - USD ($) $ in Thousands	Oct. 31, 2020	Jul. 31, 2020
Debt Securities (Details) - Schedule of available-for-sale securities, unrealized loss position [Line Items]
Unrealized Losses	$ 31
Fair Value	9,889
U.S. Treasury bills and notes [Member]
Debt Securities (Details) - Schedule of available-for-sale securities, unrealized loss position [Line Items]
Unrealized Losses	8
Fair Value	1,673
Corporate bonds [Member]
Debt Securities (Details) - Schedule of available-for-sale securities, unrealized loss position [Line Items]
Unrealized Losses	21
Fair Value	3,593
Municipal bonds [Member]
Debt Securities (Details) - Schedule of available-for-sale securities, unrealized loss position [Line Items]
Unrealized Losses	2	$ 16
Fair Value	$ 4,623	$ 1,963