PROPERTY, PLANT AND EQUIPMENT: (Details Textual) - USD ($)	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Property, Plant and Equipment [Line Items]
Depreciation	$ 1,389,000	$ 1,561,000
Impairment of Long-Lived Assets Held-for-use		3,094,000
Land [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use		2,848,000
Building [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use		122,000
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Impairment of Long-Lived Assets Held-for-use		$ 124,000