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Marketable Securities (Details 2) - USD ($) $ in Thousands | Apr. 30, 2018 | Jul. 31, 2017
--- | --- | ---
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses | $ 6 | $ 48
Fair Value | 4,816 | 19,081
Certificates of deposit [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses |  | 7
Fair Value |  | 12,155
Federal Government Sponsored Enterprise notes [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses |  | 14
Fair Value |  | 3,529
Equity [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses |  | 26
Fair Value |  | 48
U.S. Treasury notes [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses | 1 |
Fair Value | 1,689 |
Municipal bonds [Member] |  |
Schedule of Available-for-sale Securities [Line Items] |  |
Unrealized Losses | 5 | 1
Fair Value | $ 3,127 | $ 3,349

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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities categorized neither as held-to-maturity nor trading securities that have been in a continuous unrealized loss position for less than twelve months. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27290-111563 + Details
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