Note K - Stock-based Compensation - Options Exercised (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016	Apr. 30, 2015
Options Exercised (in shares)	264,500	30,750	212,250
Cash Received from Options Exercised	$ 2,609	$ 400	$ 4,143
Intrinsic Value of Options Exercised	$ 6,439	$ 943	$ 5,983