Fair Value, Measured on Recurring Basis, Gain (Loss) Included in Earnings (Details) - USD ($)	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2018	Apr. 30, 2018
Cash, Carrying Amount	$ 1,223,953	$ 1,862,458	$ 1,877,163	$ 2,348,883
Cash, Fair Value	1,223,953	1,862,458
Foreign currency option contracts, Carrying Amount	4,800	1,178
Foreign currency option contracts, Fair Value	4,800	1,178
Assets, Carrying Amount	1,228,753	1,863,636
Assets, Fair Value	1,228,753	1,863,636
Foreign currency forward contracts, Carrying Amount	7,614	4,512
Foreign currency forward contracts, Fair Value	$ 7,614	$ 4,512