Property, Plant and Equipment (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2025	Jul. 31, 2024	Apr. 30, 2025
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 654,993		$ 649,612
Less accumulated depreciation and amortization	(412,111)		(404,623)
Property, plant and equipment, net	242,882		244,989
Amortization and depreciation expense on property, plant and equipment	12,600	$ 11,200
Finance lease, right-of-use asset, accumulated amortization	30,800		31,500
Land
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	4,369		4,264
Buildings and improvements
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	133,346		133,251
Buildings and improvements - finance leases
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	11,164		11,164
Machinery and equipment
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	413,964		410,287
Machinery and equipment - finance leases
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	31,526		32,434
Software
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	34,290		34,107
Construction in progress
Property, Plant and Equipment [Line Items]
Total property, plant and equipment	$ 26,334		$ 24,105