Employee Benefit and Retirement Plans (Net Periodic Pension Cost) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Retirement Benefits [Abstract]
Interest cost	$ 4,662	$ 5,974	$ 6,269
Expected return on plan assets	(8,430)	(8,327)	(8,509)
Recognized net actuarial loss	1,761	1,692	1,648
Pension benefit cost	$ (2,007)	$ (661)	$ (592)