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Debt Securities (Details) - USD ($) $ in Thousands		Apr. 30, 2020	Jul. 31, 2019
Available-for-sale debt securities:
Amortized Cost			$ 2,534
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value		$ 12,948	2,534
Certificates of deposit [Member]
Available-for-sale debt securities:
Amortized Cost	[1]	12,864	2,234
Gross Unrealized Gains		85
Gross Unrealized Losses		(1)
Fair Value	[1]	$ 12,948	2,234
Municipal bonds [Member]
Available-for-sale debt securities:
Amortized Cost			300
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value			$ 300
[1] Each of the Company's certificates of deposit has a CUSIP, was purchased in the secondary market through a broker, and may be sold in the secondary market.

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Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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