BENEFIT PLANS: - Net periodic pension cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019
BENEFIT PLANS:
Interest cost on projected benefit obligation	$ 716	$ 1,183
Expected return on assets	(1,591)	(1,854)
Plan expenses	410	415
Recognized net actuarial loss	563	905
Settlement paid	2,929
Net periodic pension cost	$ 3,027	$ 649