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Warrants (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands |  |  |  | 12 Months Ended
--- | --- | --- | --- | ---
Apr. 08, 2019 | Jul. 22, 2016 | Jun. 02, 2016 | Apr. 30, 2020 | Apr. 30, 2019
Warrant liabilities |  |  |  |  | $ 6
Unrealized gain on warrants |  |  |  | $ 6 | $ 200
Pre-funded Warrants [Member] |  |  |  |  |
Warrant to purchase shares common stock | 3,385,680 |  |  |  |
Warrant exercise price per share | $ 0.01 |  |  |  |
Securities Purchase Agreement [Member] |  |  |  |  |
Stock issued for new issue, shares | 1,542,000 |  | 20,850 |  |
Warrant to purchase shares common stock | 4,927,680 |  | 7,298 |  |
Class of warrant or right, number of securities called by each warrant or right |  |  | 0.35 |  |
Combined purchase price per share |  |  | $ 92.00 |  |
Warrant exercise price per share | $ 3.85 |  | $ 121.60 |  |
Class of warrant or right, expiration period | 5 years |  | 5 years |  |
Number of exercised warrants |  |  |  |  |
Second Amended Purchase Agreement [Member] |  |  |  |  |
Stock issued for new issue, shares |  | 29,750 |  |  |
Warrant to purchase shares common stock |  | 8,925 |  |  |
Class of warrant or right, number of securities called by each warrant or right |  | 0.30 |  |  |
Combined purchase price per share |  | $ 135.00 |  |  |
Warrant exercise price per share |  | $ 187.20 |  |  |
Class of warrant or right, expiration period |  | 5 years |  |  |

X
- 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 No definition available. + Details
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- Definition Number of exercised warrants. + References No definition available. + Details
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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=109259400&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 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://fasb.org/us-gaap/role/ref/legacyRef -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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- Definition The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585 + Details
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- Definition Period between issuance and expiration of outstanding warrant and right embodying unconditional obligation requiring redemption by transferring asset at specified or determinable date or upon event certain to occur, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (bbb)(2) -URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258 + Details
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