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Background and Liquidity (Details Narrative) - USD ($) $ / shares in Units, $ in Thousands |  |  |  |  |  |  |  | 12 Months Ended
--- | --- | --- | --- | --- | --- | --- | --- | ---
Apr. 30, 2022 | Dec. 23, 2020 | Nov. 20, 2020 | Sep. 18, 2020 | Oct. 24, 2019 | Apr. 08, 2019 | Jan. 07, 2019 | Apr. 30, 2022 | Apr. 30, 2021
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Net Income (Loss) Attributable to Parent |  |  |  |  |  |  |  | $ 18,874 | $ 14,760
Net Cash Provided by (Used in) Operating Activities |  |  |  |  |  |  |  | 21,296 | 11,674
Cash | $ 7,900 |  |  |  |  |  |  | 7,900 |
Short-Term Investments | $ 49,384 |  |  |  |  |  |  | 49,384 |
Proceeds from initial public offering |  |  |  |  |  |  |  |  | $ 66,166
Number of common stock shares sold |  |  |  |  |  | 1,542,000 |  |  |
Deferred Offering Costs |  |  | $ 100,000 |  |  |  |  |  |
Alliance Global Partners [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Number of common stock shares sold |  |  |  |  |  |  | 12,342,506 |  |
Proceeds from issuance or sale of equity, net of issuance costs |  |  |  |  |  |  | $ 18,700 |  |
Combined purchase price per share |  |  |  |  |  |  | $ 1.51 |  |
2019 ATM Facility [Member] | Alliance Global Partners [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Proceeds from initial public offering |  |  |  |  |  |  | $ 25,000 |  |
Number of common stock shares sold |  |  |  |  |  |  | 17,595,472 |  |
Proceeds from issuance or sale of equity, net of issuance costs |  |  |  |  |  |  | $ 23,400 |  |
Combined purchase price per share |  |  |  |  |  |  | $ 1.33 |  |
Payment of sales commission |  |  |  |  |  |  | $ 800 |  |
2020 ATM Facility [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Proceeds from issuance or sale of equity, net of issuance costs |  |  |  |  |  |  |  | 75,000 |
Payment of sales commission |  |  |  |  |  |  |  | $ 25,000 |
2020 ATM Facility [Member] | Alliance Global Partners [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Number of common stock shares sold |  |  | 17,179,883 |  |  |  |  | 17,179,883 |
Proceeds from issuance or sale of equity, net of issuance costs |  |  |  |  |  |  |  | $ 50,000 |
Combined purchase price per share | $ 2.91 |  |  |  |  |  |  | $ 2.91 | $ 2.91
Payment of sales commission |  |  |  |  |  |  |  | $ 1,600 |
Proceeds from initial public offering |  |  | $ 50,000 |  |  |  |  |  |
2020 ATM Facility [Member] | Alliance Global Partners [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Aggregate purchase of common stock |  |  | $ 100,000 |  |  |  |  |  |
Stock Purchase Agreement [Member] | Aspire Capital Fund, LLC [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Number of common stock shares sold | 3,722,251 |  |  | 6,424,205 |  |  |  |  |
Proceeds from issuance or sale of equity, net of issuance costs | $ 11,800 |  |  | $ 4,000 |  |  |  |  |
Combined purchase price per share | $ 3.17 |  |  | $ 0.63 |  |  |  | $ 3.17 |
Aggregate purchase of common stock |  |  |  | $ 12,500 |  |  |  |  |
Percentage of outstanding common stock |  | 19.99% |  | 19.99% |  |  |  |  |
Shares can be issued based upon outstanding percentage |  |  |  | 3,722,251 |  |  |  |  |
Additional sales of common stock shares sold |  | 9,864,706 |  |  |  |  |  |  |
Proceeds from issuance or sale of equity, net of issuance costs | $ 1,000 |  |  |  |  |  |  |  |
Stock Purchase Agreement [Member] | Aspire Capital Fund, LLC [Member] | Maximum [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Aggregate purchase of common stock |  |  |  |  | $ 10,000 |  |  |  |
Stock Purchase Agreement One [Member] | Aspire Capital Fund, LLC [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Number of common stock shares sold |  |  |  |  |  |  |  | 5,025,000 |
Proceeds from issuance or sale of equity, net of issuance costs |  |  |  |  |  |  |  | $ 2,900 |
Combined purchase price per share | $ 0.57 |  |  |  |  |  |  | $ 0.57 |
Management [Member] |  |  |  |  |  |  |  |  |
Property, Plant and Equipment [Line Items] |  |  |  |  |  |  |  |  |
Net Income (Loss) Attributable to Parent |  |  |  |  |  |  |  | $ 18,900 | $ 14,800
Net Cash Provided by (Used in) Operating Activities |  |  |  |  |  |  |  | $ 21,400 | $ 11,700

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Namespace Prefix: |
Data Type: | na
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