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Income Taxes (Details) - USD ($)
3 Months Ended
Jul. 31, 2021
Jul. 31, 2020
Apr. 30, 2021
Income Tax Disclosure [Abstract]      
Effective income tax rate (as a percent) 24.60% 26.10%  
Valuation allowance $ 11,900,000   $ 11,800,000
Reserve for uncertain tax positions $ 0   $ 0