PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Apr. 30, 2017
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 34,251	$ 34,345
Less accumulated depreciation	(23,710)	(23,493)
Property, plant and equipment, net	10,541	10,852
Land, Buildings and Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	15,936	15,995
Furniture and equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 18,315	$ 18,350