Schedule of Available-for-sale Securities (Details) - USD ($) $ in Thousands		Apr. 30, 2022	Jul. 31, 2021
Debt Securities, Available-for-sale, Amortized Cost		$ 23,262	$ 14,021
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		1	41
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		(557)	(50)
Debt Securities, Available-for-sale		22,706	14,012
Certificates of Deposit [Member]
Debt Securities, Available-for-sale, Amortized Cost	[1]	2,000	1,200
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	[1]		3
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	[1]	(9)
Debt Securities, Available-for-sale	[1]	1,991	1,203
US Treasury Bill Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost		10,964	1,669
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax		1
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		(80)	(17)
Debt Securities, Available-for-sale		10,885	1,652
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale, Amortized Cost		3,957	6,327
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax			38
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		(452)	(33)
Debt Securities, Available-for-sale		3,505	6,332
Municipal Bonds [Member]
Debt Securities, Available-for-sale, Amortized Cost		6,341	4,825
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax		(16)
Debt Securities, Available-for-sale		$ 6,325	$ 4,825

[1] Each of the certificates of deposit held by the Company has a CUSIP, was purchased in the secondary market through a broker and may be sold in the secondary market.