Note J - Commitments and Contingencies (Details Textual) - USD ($)	3 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Apr. 30, 2019
Operating Lease, Percent of Facilities Leased	82.00%
Operating Leases, Rent Expense, Total	$ 1,700,000	$ 1,600,000
Operating Lease, Weighted Average Discount Rate, Percent			4.73%
Letters of Credit Outstanding, Amount	$ 250,000
Minimum [Member]
Lessee, Operating Lease, Term of Contract	3 years
Maximum [Member]
Lessee, Operating Lease, Term of Contract	5 years