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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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- Definition 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). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563 + Details
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