Leases (Schedule of Balance Sheet Information Related to Leases) (Details) - USD ($)  | 
Jul. 31, 2019  | 
Apr. 30, 2019  | 
Jul. 31, 2018  | 
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| Operating leases | |||
| Operating lease liabilities current | $ 1,100,411 | $ 500,000 | |
| Operating lease liabilities, long-term | 7,095,695 | ||
| Total operating lease liabilities | $ 8,196,106 | 
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- References No definition available. 
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as current. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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- Definition Present value of lessee's discounted obligation for lease payments from operating lease, classified as noncurrent. Reference 1: http://www.xbrl.org/2003/role/disclosureRef 
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