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Warrants (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands | Apr. 08, 2019 | Jul. 22, 2016 | Jun. 02, 2016 | Jul. 31, 2021 | Apr. 30, 2020
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Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |
Sale of Stock, Number of Shares Issued in Transaction | 1,542,000 |  |  |  |
Derivative Liability, Current |  |  |  |  | $ 0
Pre-funded Warrants [Member] |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | 3,385,680 |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ 0.01 |  |  |  |
Common Warrants [Member] |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | 4,927,680 |  |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights | $ 3.85 |  |  |  |
Warrants and Rights Outstanding, Term | 5 years |  |  |  |
June Purchase Agreement [Member] |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |
Sale of Stock, Number of Shares Issued in Transaction |  |  | 20,850 |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights |  |  | 7,298 |  |
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right |  |  | 0.35 |  |
[custom:CommonStockCombinedPurchasePricePerShare-0] |  |  | $ 92.00 |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights |  |  | $ 121.60 |  |
Warrants and Rights Outstanding, Term |  |  | 5 years |  |
Number of exercised warrants |  |  |  | 0 |
Second Amended Purchase Agreement [Member] |  |  |  |  |
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items] |  |  |  |  |
Sale of Stock, Number of Shares Issued in Transaction |  | 29,750 |  |  |
Class of Warrant or Right, Number of Securities Called by Warrants or Rights |  | 8,925 |  |  |
Class of Warrant or Right, Number of Securities Called by Each Warrant or Right |  | 0.30 |  |  |
[custom:CommonStockCombinedPurchasePricePerShare-0] |  | $ 135.00 |  |  |
Class of Warrant or Right, Exercise Price of Warrants or Rights |  | $ 187.20 |  |  |
Warrants and Rights Outstanding, Term |  | 5 years |  |  |
Number of exercised warrants |  |  |  | 0 |

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- Definition Exercise price per share or per unit of warrants or rights outstanding. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
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- Definition Number of securities into which each warrant or right may be converted. For example, but not limited to, each warrant may be converted into two shares. + References No definition available. + Details
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- Definition Number of securities into which the class of warrant or right may be converted. For example, but not limited to, 500,000 warrants may be converted into 1,000,000 shares. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=123467817&loc=d3e21475-112644 + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 + Details
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