Income Taxes (Details) - USD ($)	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
Income Taxes (Details) [Line Items]
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 1,900,000
Tax Credit Carryforward, Expiration Year		2023
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued	119,000	$ 64,000
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense	60,000	$ 54,000
Decrease in Unrecognized Tax Benefits is Reasonably Possible	1.3
Domestic Tax Authority [Member]
Income Taxes (Details) [Line Items]
Operating Loss Carryforwards	24,600,000
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	16,400,000
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration	8,200,000
Tax Credit Carryforward, Amount	10,000,000
Annual Limitation [Member] | Domestic Tax Authority [Member]
Income Taxes (Details) [Line Items]
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration	$ 3,400,000