Note J - Commitments and Contingencies (Details Textual) - USD ($)	6 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Apr. 30, 2019
Operating Lease, Percent of Facilities Leased	81.00%
Operating Leases, Rent Expense, Total	$ 3,500,000	$ 3,300,000
Operating Lease, Weighted Average Discount Rate, Percent			4.73%
Letters of Credit Outstanding, Amount	$ 500,000
Minimum [Member]
Lessee, Operating Lease, Term of Contract	3 years
Maximum [Member]
Lessee, Operating Lease, Term of Contract	5 years