Annual report pursuant to Section 13 and 15(d)

Income Taxes (Deferred Tax Asset Valuation Allowance Rollforward) (Details)

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Income Taxes (Deferred Tax Asset Valuation Allowance Rollforward) (Details) - USD ($)
12 Months Ended
Apr. 30, 2017
Apr. 30, 2016
Income Tax Disclosure [Abstract]    
Valuation allowance, beginning of year $ (9,068,774) $ (8,240,200)
(Increase) during period (402,888) (828,574)
Valuation allowance, ending balance $ (9,471,662) $ (9,068,774)