PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Oct. 31, 2018	Apr. 30, 2018
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,233	$ 34,171
Less accumulated depreciation	(25,026)	(24,426)
Property, plant and equipment, net	9,207	9,745
Land, buildings and improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	15,946	15,932
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 18,287	$ 18,239