Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2024	Oct. 31, 2023	Oct. 31, 2024	Oct. 31, 2023	Apr. 30, 2024
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 655,788		$ 655,788		$ 653,724
Less accumulated amortization and depreciation	(399,935)		(399,935)		(381,263)
Property, plant and equipment, net	255,853		255,853		272,461
Amortization and depreciation expense on property, plant and equipment	11,900	$ 9,700	23,100	$ 19,500
Finance lease, right-of-use asset, accumulated amortization	31,600		31,600		31,700
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	4,475		4,475		4,475
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	135,717		135,717		131,663
Buildings and improvements - finance leases
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	11,164		11,164		11,164
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	399,846		399,846		370,940
Machinery and equipment - finance leases
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	32,462		32,462		32,173
Software
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	31,275		31,275		39,252
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 40,849		$ 40,849		$ 64,057