Property, Plant and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2024	Apr. 30, 2023	Apr. 30, 2022
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 653,724	$ 573,589
Less accumulated amortization and depreciation	(381,263)	(354,174)
Property, Plant and Equipment, Net, Total	272,461	219,415
Amortization and depreciation expense on property, plant and equipment	41,200	37,900	$ 38,000
Finance Lease, Right-of-Use Asset, Accumulated Amortization	31,700	31,900
Land [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,475	4,475
Buildings And Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	131,663	121,903
Building And Improvements - Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,164	11,164
Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	370,940	331,146
Machinery And Equipment - Capital Leases [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	32,173	29,869
Construction In Progress [Member]
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	64,057	45,710
Property, Plant and Equipment, Net, Total	272,461	219,415
Software and Software Development Costs
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 39,252	$ 29,322