Pension Benefits (Net Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jan. 31, 2022	Jan. 31, 2021	Jan. 31, 2022	Jan. 31, 2021
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Interest cost	$ 450	$ 1,165	$ 3,148	$ 3,496
Expected return on plan assets	(515)	(2,107)	(3,601)	(6,322)
Recognized net actuarial loss	167	441	1,164	1,321
Net periodic pension benefit	$ 102	$ (501)	$ 711	$ (1,505)