| Accounts Receivable - Accounts Receivable Balance (Details) - USD ($) | Apr. 30, 2021 | Apr. 30, 2020 | Apr. 29, 2015 | Sep. 30, 2014 | Sep. 16, 2011 | 
|---|---|---|---|---|---|
| Receivables [Abstract] | Ìý | Ìý | Ìý | Ìý | Ìý | 
| Accounts receivable | $ 30,264,393 | $ 22,786,847 | Ìý | Ìý | Ìý | 
| Long-term contractual accounts receivable | (10,249,833) | (6,701,136) | $ (671,291) | $ (772,793) | $ (772,793) | 
| Accounts receivable, current | 20,014,560 | 16,085,711 | Ìý | Ìý | Ìý | 
| Less: Allowance for doubtful accounts | (3,289,816) | (1,758,920) | Ìý | Ìý | Ìý | 
| Accounts receivable, net | $ 16,724,744 | $ 14,326,791 | Ìý | Ìý | Ìý | 
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- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount, before allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business, classified as noncurrent. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount, after allowance for credit loss, of right to consideration from customer for product sold and service rendered in normal course of business. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Amount of allowance for credit loss on accounts receivable. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- References No definition available. 
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