Employee Benefit and Retirement Plans (Net Periodic Pension Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Retirement Benefits [Abstract]
Interest cost	$ 5,974	$ 6,269	$ 5,727
Expected return on plan assets	(8,327)	(8,509)	(8,936)
Recognized net actuarial loss	1,692	1,648	1,601
Pension benefit cost	$ (661)	$ (592)	$ (1,608)