Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2023	Oct. 31, 2022	Oct. 31, 2023	Oct. 31, 2022	Apr. 30, 2023
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 601,936		$ 601,936		$ 573,589
Less accumulated amortization and depreciation	(366,764)		(366,764)		(354,174)
Property, Plant and Equipment, Net, Total	235,172		235,172		219,415
Amortization and depreciation expense on property, plant and equipment	9,700	$ 9,700	19,500	$ 19,400
Finance lease, right-of-use asset, accumulated amortization	31,600		31,600		31,900
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	4,475		4,475		4,475
Buildings and improvements
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	123,129		123,129		121,903
Buildings and improvements - finance leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	11,164		11,164		11,164
Machinery and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	343,341		343,341		331,146
Machinery and equipment - finance leases
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	31,031		31,031		29,869
Software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	29,597		29,597		29,322
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, gross	$ 59,199		$ 59,199		$ 45,710