Note 5 - Property, Plant and Equipment - Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Mar. 31, 2023	Oct. 01, 2022
Property, Plant and Equipment, Gross	$ 757,051	$ 734,432	$ 720,482
Less: accumulated depreciation	(451,195)	(433,220)	(436,753)
Property, plant and equipment, net	305,856	301,212	283,729
Land and Land Improvements [Member]
Property, Plant and Equipment, Gross	48,385	46,978	43,686
Building and Building Improvements [Member]
Property, Plant and Equipment, Gross	231,736	214,110	204,767
Machinery and Equipment [Member]
Property, Plant and Equipment, Gross	440,206	421,067	421,015
Office Furniture, Vehicles and Computer Software [Member]
Property, Plant and Equipment, Gross	13,149	11,738	10,326
Construction in Progress [Member]
Property, Plant and Equipment, Gross	$ 23,575	$ 40,539	$ 40,688