Pension Benefits (Net Periodic Pension Cost) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Pension and Other Postretirement Benefits Cost (Reversal of Cost) [Abstract]
Interest cost	$ 1,349	$ 1,166	$ 2,698	$ 2,331
Expected return on plan assets	(1,543)	(2,108)	(3,086)	(4,215)
Recognized net actuarial loss	498	440	997	880
Net periodic pension benefit	$ 304	$ (502)	$ 609	$ (1,004)